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| author | Paul Buetow <paul@buetow.org> | 2026-03-27 17:49:53 +0200 |
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| committer | Paul Buetow <paul@buetow.org> | 2026-03-27 17:49:53 +0200 |
| commit | ffd6ec347dba2c6e9b15f93e9df6168977def452 (patch) | |
| tree | ddb34f3be765a31036af9e57bdff092e6cdac3ed | |
| parent | b768f53a1eae8b70e6fabfb83fa339f4cf4771b9 (diff) | |
cleanup
15 files changed, 0 insertions, 3018 deletions
diff --git a/gemfeed/.rcmbackup/2008-06-26-perl-poetry.gmi.tpl.49f27f3f6cfb364dfb6ffe2de2faa0100ea27a3b5b8d237fb8934c293dfc74a9 b/gemfeed/.rcmbackup/2008-06-26-perl-poetry.gmi.tpl.49f27f3f6cfb364dfb6ffe2de2faa0100ea27a3b5b8d237fb8934c293dfc74a9 deleted file mode 100644 index bb16451a..00000000 --- a/gemfeed/.rcmbackup/2008-06-26-perl-poetry.gmi.tpl.49f27f3f6cfb364dfb6ffe2de2faa0100ea27a3b5b8d237fb8934c293dfc74a9 +++ /dev/null @@ -1,172 +0,0 @@ -# Perl Poetry - -> Published at 2008-06-26T21:43:51+01:00; Updated at 2021-05-04 - -Here are some Perl Poems I wrote. They don't do anything useful when you run them, but they don't produce a compiler error either. They only exist for fun and demonstrate what you can do with Perl syntax. - -Wikipedia: "Perl poetry is the practice of writing poems that can be compiled as legal Perl code, for example the piece known as Black Perl. Perl poetry is made possible by the large number of English words that are used in the Perl language. New poems are regularly submitted to the community at PerlMonks." - -=> https://en.wikipedia.org/wiki/Perl - -``` - '\|/' * --- * ----- - /|\ ____ - ' | ' {_ o^> * - : -_ /) - : ( ( .-''`'. - . \ \ / \ - . \ \ / \ - \ `-' `'. - \ . ' / `. - \ ( \ ) ( .') - ,, t '. | / | ( - '|``_/^\___ '| |`'-..-'| ( () -_~~|~/_|_|__/|~~~~~~~ | / ~~~~~ | | ~~~~~~~~ - -_ |L[|]L|/ | |\ MJP ) ) - ( |( / /| - ~~ ~ ~ ~~~~ | /\\ / /| | - || \\ _/ / | | - ~ ~ ~~~ _|| (_/ (___)_| |Nov291999 - (__) (____) -``` - -<< template::inline::toc - -## math.pl - -```perl -#!/usr/bin/perl - -# (C) 2006 by Paul C. Buetow - -goto library for study $math; -BEGIN { s/earching/ books/ -and read $them, $at, $the } library: - -our $topics, cos and tan, -require strict; import { of, tied $patience }; - -do { int'egrate'; sub trade; }; -do { exp'onentize' and abs'olutize' }; -study and study and study and study; - -foreach $topic ({of, math}) { -you, m/ay /go, to, limits } - -do { not qw/erk / unless $success -and m/ove /o;$n and study }; - -do { int'egrate'; sub trade; }; -do { exp'onentize' and abs'olutize' }; -study and study and study and study; - -grep /all/, exp'onents' and cos'inuses'; -/seek results/ for @all, log'4rithms'; - -'you' =~ m/ay /go, not home -unless each %book ne#ars -$completion; - -do { int'egrate'; sub trade; }; -do { exp'onentize' and abs'olutize' }; - -#at -home: //ig,'nore', time and sleep $very =~ s/tr/on/g; -__END__ - -``` - -## christmas.pl - -```perl -#!/usr/bin/perl - -# (C) 2006 by Paul C. Buetow - -Christmas:{time;#!!! - -Children: do tell $wishes; - -Santa: for $each (@children) { -BEGIN { read $each, $their, wishes and study them; use Memoize#ing - -} use constant gift, 'wrapping'; -package Gifts; pack $each, gift and bless $each and goto deliver -or do import if not local $available,!!! HO, HO, HO; - -redo Santa, pipe $gifts, to_childs; -redo Santa and do return if last one, is, delivered; - -deliver: gift and require diagnostics if our $gifts ,not break; -do{ use NEXT; time; tied $gifts} if broken and dump the, broken, ones; -The_children: sleep and wait for (each %gift) and try { to => untie $gifts }; - -redo Santa, pipe $gifts, to_childs; -redo Santa and do return if last one, is, delivered; - -The_christmas_tree: formline s/ /childrens/, $gifts; -alarm and warn if not exists $Christmas{ tree}, @t, $ENV{HOME}; -write <<EMail - to the parents to buy a new christmas tree!!!!111 - and send the -EMail -;wait and redo deliver until defined local $tree; - -redo Santa, pipe $gifts, to_childs; -redo Santa and do return if last one, is, delivered ;} - -END {} our $mission and do sleep until next Christmas ;} - -__END__ - -This is perl, v5.8.8 built for i386-freebsd-64int -``` - -## shopping.pl - -```perl -#!/usr/bin/perl - -# (C) 2007 by Paul C. Buetow - -BEGIN{} goto mall for $shopping; - -m/y/; mall: seek$s, cool products(), { to => $sell }; -for $their (@business) { to:; earn:; a:; lot:; of:; money: } - -do not goto home and exit mall if exists $new{product}; -foreach $of (q(uality rich products)){} package products; - -our $news; do tell cool products() and do{ sub#tract -cool{ $products and shift @the, @bad, @ones; - -do bless [q(uality)], $products -and return not undef $stuff if not (local $available) }}; - -do { study and study and study for cool products() } -and do { seek $all, cool products(), { to => $buy } }; - -do { write $them, $down } and do { order: foreach (@case) { package s } }; -goto home if not exists $more{money} or die q(uerying) ;for( @money){}; - -at:;home: do { END{} and:; rest:; a:; bit: exit $shopping } -and sleep until unpack$ing, cool products(); - -__END__ -This is perl, v5.8.8 built for i386-freebsd-64int -``` - -## More... - -Did you like what you saw? Have a look at Codeberg to see my other poems too: - -=> https://codeberg.org/snonux/perl-poetry - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -Other related posts are: - -<< template::inline::rindex perl - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2008-12-29-using-my-nokia-n95-for-fixing-my-mta.gmi.8f549e73479399b4d0e722c80728d34887bad242e066320ff17119682ffdf5d2 b/gemfeed/.rcmbackup/2008-12-29-using-my-nokia-n95-for-fixing-my-mta.gmi.8f549e73479399b4d0e722c80728d34887bad242e066320ff17119682ffdf5d2 deleted file mode 100644 index 33484e6c..00000000 --- a/gemfeed/.rcmbackup/2008-12-29-using-my-nokia-n95-for-fixing-my-mta.gmi.8f549e73479399b4d0e722c80728d34887bad242e066320ff17119682ffdf5d2 +++ /dev/null @@ -1,41 +0,0 @@ -# Using my Nokia N95 for fixing my MTA - -> Published at 2008-12-29T09:10:41+00:00; Updated at 2021-12-01 - -``` - - _ - |E] - .-|=====-. - | | mail | - ___|________| - || - || - || www - ,;, || )_(,;;;, - <_> \ || \|/ \_/ - \|/ \\|| \\| |// -_jgs_\|//_\\|///_\V/_\|//__ - Art by Joan Stark -``` - -The last week I was in Vidin, Bulgaria with no internet access and I had to fix my MTA (Postfix) at host.0.buetow.org which serves E-Mail for all my customers at P. B. Labs. Good, that I do not guarantee high availability on my web services (I've to do a full time job somewhere else too). - -My first attempt to find an internet café, which was working during Christmastime, failed. However, I found with my N95 phone lots of free WLAN hotspots. The hotspots refused me logging into my server using SSH as I have configured a non-standard port for SSH for security reasons. Without knowing the costs, I used the GPRS internet access of my German phone provider (yes, I had to pay roaming fees). - -=> ./using-my-nokia-n95-for-fixing-my-mta/nokia-n95.jpg Picture of a Nokia N95 - -With Putty for N95 and configuring Postfix with Vim and the T9 input mechanism, I managed to fix the problem. But it took half of an hour: - -* First, getting a shell prompt -* Second, use the "tail" command to analyse the Postfix logs -* Third, use the "sed" command to fix a syntax error in the Postfix config -* Fourth, restart Postfix - -It was a pain in the ass. My next mobile phone MUST have a full QWERTY keyboard. This would have made my life lots easier. :) - -At the moment I am in Sofia, Bulgaria. Here I can use at least an unprotected WLAN hotspot which belongs to one of the neighbours which I don’t know in person, and it is not blocking any port at all :) - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2009-02-13-sgi-onyx-3200.gmi.e8c19f9d9486a1d74c8a1074d627e76fa9bf9aaa54d9dbd59a106a495c02c138 b/gemfeed/.rcmbackup/2009-02-13-sgi-onyx-3200.gmi.e8c19f9d9486a1d74c8a1074d627e76fa9bf9aaa54d9dbd59a106a495c02c138 deleted file mode 100644 index fd10c754..00000000 --- a/gemfeed/.rcmbackup/2009-02-13-sgi-onyx-3200.gmi.e8c19f9d9486a1d74c8a1074d627e76fa9bf9aaa54d9dbd59a106a495c02c138 +++ /dev/null @@ -1,68 +0,0 @@ -# SGI Onyx 3200 - -> Published at 2025-02-13T21:17:16+02:00 - -For nostalgia, I've kept this output of the 'dmesg' around. It's from an SGI Onyx 3200 graphics supercomputer running IRIX with the following specs: - -* 4 x 400 MHz IP35 MIPS CPUs -* 4GB of RAM - -=> ./sgi-onyx-3200/desk.webp - -We used this monster when I was a student worker at the Fraunhofer Institute for Production Technology around the year 2006. It operated a walk-in 2-sided 3D cave (unfortunately, I don't have any pictures of that cave), where you could literally walk around with a set of VR glasses and see everything in 3D (that was when there wasn't any Oculus Quest yet). That was useful for running industrial simulations. - -``` -4 400 MHZ IP35 Processors -CPU: MIPS R12000 Processor Chip Revision: 3.5 -FPU: MIPS R12010 Floating Point Chip Revision: 3.5 -Main memory size: 4096 Mbytes -Instruction cache size: 32 Kbytes -Data cache size: 32 Kbytes -Secondary unified instruction/data cache size: 8 Mbytes -Integral SCSI controller 8: Version Fibre Channel QL2200A -Integral SCSI controller 6: Version QL12160, single ended -Integral SCSI controller 7: Version QL12160, low voltage differential -Integral SCSI controller 9: Version IEEE1394 SBP2 - IEEE1394 CDROM: node 1010031001a454 port 0 on SCSI controller 9 -Integral SCSI controller 0: Version Fibre Channel QL2200A - Disk drive: unit 1 on SpCSI controller 0 - Disk drive: unit 2 on SCSI controller 0 -Integral SCSI controller 5: Version IEEE1394 SBP2 - IEEE1394 CDROM: node 1010031001c080 port 0 on SCSI controller 5 -IOC3 serial port: tty3 -IOC3 serial port: tty4 -IOC3 serial port: tty10 -IOC3 serial port: tty11 -IOC3 serial port: tty12 -IOC3 serial port: tty5 -IOC3 serial port: tty6 -IOC3 serial port: tty7 -IOC3 serial port: tty8 -IOC3 serial port: tty9 -Graphics board: InfiniteReality3 -Graphics board: InfiniteReality3 -Gigabit Ethernet: eg0, module 001c04, pci_bus 2, pci_slot 2, firmware version 12.4.10 -Fast Ethernet: ef1, version 1, module 001c07, pci 4 -Integral Fast Ethernet: ef0, version 1, module 001c04, pci 4 -Iris Audio Processor: version RAD revision 13.0, number 1 -IOC3 external interrupts: 2 -IOC3 external interrupts: 1 -IEEE 1394 High performance serial bus controller 0: Type: OHCI, Version 0 0 -IEEE 1394 High performance serial bus controller 1: Type: OHCI, Version 0 0 -USB controller: type OHCI -USB Human Interface Device: device id 1 type keyboard -USB Human Interface Device: device id 1 type mouse -USB controller: type OHCI -USB Human Interface Device: device id 0 type keyboard -USB Human Interface Device: device id 0 type mouse -``` - -=> ./sgi-onyx-3200/collage.webp - -I was mainly working on drilling simulations on this machine. Sometimes I worked directly at one of the 2 terminal screens of the Onyx, or often I used a nearby Linux machine and forwarded the X11 windows to my local screen. - -=> ./sgi-onyx-3200/collage2.webp - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2010-04-09-standard-ml-and-haskell.gmi.tpl.94827a5494a2149e0e0f68d54010656f2fc707f8265377a801426e1e04351f3b b/gemfeed/.rcmbackup/2010-04-09-standard-ml-and-haskell.gmi.tpl.94827a5494a2149e0e0f68d54010656f2fc707f8265377a801426e1e04351f3b deleted file mode 100644 index a3d3ed79..00000000 --- a/gemfeed/.rcmbackup/2010-04-09-standard-ml-and-haskell.gmi.tpl.94827a5494a2149e0e0f68d54010656f2fc707f8265377a801426e1e04351f3b +++ /dev/null @@ -1,176 +0,0 @@ -# Standard ML and Haskell - -> Published at 2010-04-09T22:57:36+01:00 - -I am currently looking into the functional programming language Standard ML (aka SML). The purpose is to refresh my functional programming skills and to learn something new too. Since I already knew a little Haskell, I could not help myself, and I also implemented the same exercises in Haskell. - -As you will see, SML and Haskell are very similar (at least when it comes to the basics). However, the syntax of Haskell is a bit more "advanced". Haskell utilizes fewer keywords (e.g. no val, end, fun, fn ...). Haskell also allows to write down the function types explicitly. What I have been missing in SML so far is the so-called pattern guards. Although this is a very superficial comparison for now, so far, I like Haskell more than SML. Nevertheless, I thought it would be fun to demonstrate a few simple functions of both languages to show off the similarities. - -Haskell is also a "pure functional" programming language, whereas SML also makes explicit use of imperative concepts. I am by far not a specialist in either of these languages, but here are a few functions implemented in both SML and Haskell: - -<< template::inline::toc - -## Defining a multi-data type - -Standard ML: - -```sml -datatype ’a multi - = EMPTY - | ELEM of ’a - | UNION of ’a multi * ’a multi -``` - -Haskell: - -```haskell -data (Eq a) => Multi a - = Empty - | Elem a - | Union (Multi a) (Multi a) - deriving Show -``` - -## Processing a multi - -Standard ML: - -```sml -fun number (EMPTY) _ = 0 - | number (ELEM x) w = if x = w then 1 else 0 - | number (UNION (x,y)) w = (number x w) + (number y w) -fun test_number w = number (UNION (EMPTY, \ - UNION (ELEM 4, UNION (ELEM 6, \ - UNION (UNION (ELEM 4, ELEM 4), EMPTY))))) w -``` - -Haskell: - -```haskell -number Empty _ = 0 -number (Elem x) w = if x == w then 1 else 0 -test_number w = number (Union Empty \ - (Union (Elem 4) (Union (Elem 6) \ - (Union (Union (Elem 4) (Elem 4)) Empty)))) w -``` - -## Simplify function - -Standard ML: - -```sml -fun simplify (UNION (x,y)) = - let fun is_empty (EMPTY) = true | is_empty _ = false - val x’ = simplify x - val y’ = simplify y - in if (is_empty x’) andalso (is_empty y’) - then EMPTY - else if (is_empty x’) - then y’ - else if (is_empty y’) - then x’ - else UNION (x’, y’) - end - | simplify x = x -``` - -Haskell: - -```haskell -simplify (Union x y) - | (isEmpty x’) && (isEmpty y’) = Empty - | isEmpty x’ = y’ - | isEmpty y’ = x’ - | otherwise = Union x’ y’ - where - isEmpty Empty = True - isEmpty _ = False - x’ = simplify x - y’ = simplify y -simplify x = x -``` - -## Delete all - -Standard ML: - -```sml -fun delete_all m w = - let fun delete_all’ (ELEM x) = if x = w then EMPTY else ELEM x - | delete_all’ (UNION (x,y)) = UNION (delete_all’ x, delete_all’ y) - | delete_all’ x = x - in simplify (delete_all’ m) - end -``` - -Haskell: - -```haskell -delete_all m w = simplify (delete_all’ m) - where - delete_all’ (Elem x) = if x == w then Empty else Elem x - delete_all’ (Union x y) = Union (delete_all’ x) (delete_all’ y) - delete_all’ x = x -``` - -## Delete one - -Standard ML: - -```sml -fun delete_one m w = - let fun delete_one’ (UNION (x,y)) = - let val (x’, deleted) = delete_one’ x - in if deleted - then (UNION (x’, y), deleted) - else let val (y’, deleted) = delete_one’ y - in (UNION (x, y’), deleted) - end - end - | delete_one’ (ELEM x) = - if x = w then (EMPTY, true) else (ELEM x, false) - | delete_one’ x = (x, false) - val (m’, _) = delete_one’ m - in simplify m’ - end -``` - -Haskell: - -```haskell -delete_one m w = do - let (m’, _) = delete_one’ m - simplify m’ - where - delete_one’ (Union x y) = - let (x’, deleted) = delete_one’ x - in if deleted - then (Union x’ y, deleted) - else let (y’, deleted) = delete_one’ y - in (Union x y’, deleted) - delete_one’ (Elem x) = - if x == w then (Empty, True) else (Elem x, False) - delete_one’ x = (x, False) -``` - -## Higher-order functions - -The first line is always the SML code, the second line the Haskell variant: - -``` -fun make_map_fn f1 = fn (x,y) => f1 x :: y -make_map_fn f1 = \x y -> f1 x : y - -fun make_filter_fn f1 = fn (x,y) => if f1 x then x :: y else y -make_filter_fn f1 = \x y -> if f1 then x : y else y - -fun my_map f l = foldr (make_map_fn f) [] l -my_map f l = foldr (make_map_fn f) [] l - -fun my_filter f l = foldr (make_filter_fn f) [] l -my_filter f l = foldr (make_filter_fn f) [] l -``` - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2010-05-07-lazy-evaluation-with-standard-ml.gmi.f3bdd7120c249354bf0503c9ed61a11918e2db7b75fa0bd93a5b7402d87cce43 b/gemfeed/.rcmbackup/2010-05-07-lazy-evaluation-with-standard-ml.gmi.f3bdd7120c249354bf0503c9ed61a11918e2db7b75fa0bd93a5b7402d87cce43 deleted file mode 100644 index 738d54a8..00000000 --- a/gemfeed/.rcmbackup/2010-05-07-lazy-evaluation-with-standard-ml.gmi.f3bdd7120c249354bf0503c9ed61a11918e2db7b75fa0bd93a5b7402d87cce43 +++ /dev/null @@ -1,102 +0,0 @@ -# Lazy Evaluation with Standard ML - -> Published at 2010-05-07T08:17:59+01:00 - -``` - - _____|~~\_____ _____________ - _-~ \ | \ - _- | ) \ |__/ \ \ - _- ) | | | \ \ - _- | ) / |--| | | - __-_______________ /__/_______| |_________ -( |---- | | - `---------------'--\\\\ .`--' -Glyde- - `|||| -``` - -In contrast to Haskell, Standard SML does not use lazy evaluation by default but an eager evaluation. - -=> https://en.wikipedia.org/wiki/Eager_evaluation -=> https://en.wikipedia.org/wiki/Lazy_evaluation - - -You can solve specific problems with lazy evaluation easier than with eager evaluation. For example, you might want to list the number Pi or another infinite list of something. With the help of lazy evaluation, each element of the list is calculated when it is accessed first, but not earlier. - -## Emulating lazy evaluation in SML - -However, it is possible to emulate lazy evaluation in most eager evaluation languages. This is how it is done with Standard ML (with some play with an infinite list of natural number tuples filtering out 0 elements): - -``` -type ’a lazy = unit -> ’a; - -fun force (f:’a lazy) = f (); -fun delay x = (fn () => x) : ’a lazy; - -datatype ’a sequ = NIL | CONS of ’a * ’a sequ lazy; - -fun first 0 s = [] - | first n NIL = [] - | first n (CONS (i,r)) = i :: first (n-1) (force r); - -fun filters p NIL = NIL - | filters p (CONS (x,r)) = - if p x - then CONS (x, fn () => filters p (force r)) - else - filters p (force r); - -fun nat_pairs () = - let - fun from_pair (x,0) = - CONS ((x,0), fn () => from_pair (0,x+1)) - | from_pair (up,dn) = - CONS ((up,dn), fn () => from_pair (up+1,dn-1)) - in from_pair (0,0) - end; - -(* Test -val test = first 10 (nat_pairs ()) -*) - -fun nat_pairs_not_null () = - filters (fn (x,y) => x > 0 andalso y > 0) (nat_pairs ()); - -(* Test -val test = first 10 (nat_pairs_not_null ()); -*) -``` - -=> http://smlnj.org/ - -## Real laziness with Haskell - -As Haskell already uses lazy evaluation by default, there is no need to construct a new data type. Lists in Haskell are lazy by default. You will notice that the code is also much shorter and easier to understand than the SML version. - -``` -{- Just to make it look like the ML example -} -first = take -filters = filter - -{- Implementation -} -nat_pairs = from_pair 0 0 - where - from_pair x 0 = [x,0] : from_pair 0 (x+1) - from_pair up dn = [up,dn] : from_pair (up+1) (dn-1) - -{- Test: -first 10 nat_pairs --} - -nat_pairs_not_null = filters (\[x,y] -> x > 0 && y > 0) nat_pairs - -{- Test: -first 10 nat_pairs_not_null --} -``` - -=> http://www.haskell.org/ - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2010-05-09-the-fype-programming-language.gmi.tpl.9797b465fab8bb78c39245ea4138babc12364c18bb386e7d7543fc61b8b529dc b/gemfeed/.rcmbackup/2010-05-09-the-fype-programming-language.gmi.tpl.9797b465fab8bb78c39245ea4138babc12364c18bb386e7d7543fc61b8b529dc deleted file mode 100644 index 683e2357..00000000 --- a/gemfeed/.rcmbackup/2010-05-09-the-fype-programming-language.gmi.tpl.9797b465fab8bb78c39245ea4138babc12364c18bb386e7d7543fc61b8b529dc +++ /dev/null @@ -1,512 +0,0 @@ -# The Fype Programming Language - -> Published at 2010-05-09T12:48:29+01:00; Updated at 2021-05-05 - -Fype is an interpreted programming language created by me for learning and fun. The interpreter is written in C. It has been tested on FreeBSD and NetBSD and may also work on other Unix like operating systems such as Linux based ones. Besides learning and fun, there is no other use case of why Fype exists as many other programming languages are much faster and more powerful. - -The Fype syntax is straightforward and uses a maximum look ahead of 1 and an effortless top-down parsing mechanism. Fype is parsing and interpreting its code simultaneously. This means that syntax errors are only detected during program runtime. - -Fype is a recursive acronym and means "Fype is For Your Program Execution" or "Fype is Free Yak Programmed for ELF". You could also say, "It's not a hype - it's Fype!". - -``` - ____ _ __ - / / _|_ _ _ __ ___ _ _ ___ __ _| |__ / _|_ _ - / / |_| | | | '_ \ / _ \ | | | |/ _ \/ _` | '_ \ | |_| | | | - _ / /| _| |_| | |_) | __/ | |_| | __/ (_| | | | |_| _| |_| | -(_)_/ |_| \__, | .__/ \___| \__, |\___|\__,_|_| |_(_)_| \__, | - |___/|_| |___/ |___/ -``` - -<< template::inline::toc - -## Object-oriented C style - -The Fype interpreter is written in an object-oriented style of C. Each "main component" has its own .h and .c file. There is a struct type for each (most components at least) component, which can be initialized using a "COMPONENT_new" function and destroyed using a "COMPONENT_delete" function. Method calls follow the same schema, e.g. "COMPONENT_METHODNAME". There is no such as class inheritance and polymorphism involved. - -To give you an idea of how it works here as an example is a snippet from the main Fype "class header": - -```c -typedef struct { - Tupel *p_tupel_argv; // Contains command line options - List *p_list_token; // Initial list of token - Hash *p_hash_syms; // Symbol table - char *c_basename; -} Fype; -``` - -And here is a snippet from the primary Fype "class implementation": - -```c -Fype* -fype_new() { - Fype *p_fype = malloc(sizeof(Fype)); - - p_fype->p_hash_syms = hash_new(512); - p_fype->p_list_token = list_new(); - p_fype->p_tupel_argv = tupel_new(); - p_fype->c_basename = NULL; - - garbage_init(); - - return (p_fype); -} - -void -fype_delete(Fype *p_fype) { - argv_tupel_delete(p_fype->p_tupel_argv); - - hash_iterate(p_fype->p_hash_syms, symbol_cleanup_hash_syms_cb); - hash_delete(p_fype->p_hash_syms); - - list_iterate(p_fype->p_list_token, token_ref_down_cb); - list_delete(p_fype->p_list_token); - - if (p_fype->c_basename) - free(p_fype->c_basename); - - garbage_destroy(); -} - -int -fype_run(int i_argc, char **pc_argv) { - Fype *p_fype = fype_new(); - - // argv: Maintains command line options - argv_run(p_fype, i_argc, pc_argv); - - // scanner: Creates a list of token - scanner_run(p_fype); - - // interpret: Interpret the list of token - interpret_run(p_fype); - - fype_delete(p_fype); - - return (0); -} -``` - -## Data types - -Fype uses auto type conversion. However, if you want to know what's going on, you may take a look at the following basic data types: -* integer - Specifies a number -* double - Specifies a double-precision number -* string - Specifies a string -* number - May be an integer or a double number -* any- May be any type above -* void - No type -* identifier - It's a variable name or a procedure name, or a function name - -There is no boolean type, but we can use the integer values 0 for false and 1 for true. There is support for explicit type casting too. - -## Syntax - -### Comments - -Text from a # character until the end of the current line is considered being a comment. Multi-line comments may start with an #* and with a *# anywhere. Exceptions are if those signs are inside of strings. - -### Variables - -Variables are defined with the "my" keyword (inspired by Perl :-). If you don't assign a value during declaration, it uses the default integer value 0. Variables may be changed during program runtime. Variables may be deleted using the "undef" keyword! Example: - -``` -my foo = 1 + 2; -say foo; - -my bar = 12, baz = foo; -say 1 + bar; -say bar; - -my baz; -say baz; # Will print out 0 -``` - -You may use the "defined" keyword to check if an identifier has been defined or not: - -``` -ifnot defined foo { - say "No foo yet defined"; -} - -my foo = 1; - -if defined foo { - put "foo is defined and has the value "; - say foo; -} -``` - -### Synonyms - -Each variable can have as many synonyms as wished. A synonym is another name to access the content of a specific variable. Here is an example of how to use it: - -``` -my foo = "foo"; -my bar = \foo; -foo = "bar"; - -# The synonym variable should now also set to "bar" -assert "bar" == bar; -``` - -Synonyms can be used for all kind of identifiers. It's not limited to standard variables but can also be used for function and procedure names (more about functions and procedures later). - -``` -# Create a new procedure baz -proc baz { say "I am baz"; } - -# Make a synonym baz, and undefine baz -my bay = \baz; - -undef baz; - -# bay still has a reference of the original procedure baz -bay; # this prints aut "I am baz" -``` - -The "syms" keyword gives you the total number of synonyms pointing to a specific value: - -``` -my foo = 1; -say syms foo; # Prints 1 - -my baz = \foo; -say syms foo; # Prints 2 -say syms baz; # Prints 2 - -undef baz; -say syms foo; # Prints 1 -``` - -## Statements and expressions - -A Fype program is a list of statements. Each keyword, expression or function call is part of a statement. Each statement is ended with a semicolon. Example: - -``` -my bar = 3, foo = 1 + 2; -say foo; -exit foo - bar; -``` - -### Parenthesis - -All parenthesis for function arguments is optional. They help to make the code better readable. They also help to force the precedence of expressions. - -### Basic expressions - -Any "any" value holding a string will be automatically converted to an integer value. - -``` -(any) <any> + <any> -(any) <any> - <any> -(any) <any> * <any> -(any) <any> / <any> -(integer) <any> == <any> -(integer) <any> != <any> -(integer) <any> <= <any> -(integer) <any> gt <any> -(integer) <any> <> <any> -(integer) <any> gt <any> -(integer) not <any> -``` - -### Bitwise expressions - -``` -(integer) <any> :< <any> -(integer) <any> :> <any> -(integer) <any> and <any> -(integer) <any> or <any> -(integer) <any> xor <any> -``` - -### Numeric expressions - -``` -(number) neg <number> -``` - -... returns the negative value of "number": - -``` -(integer) no <integer> -``` - -... returns 1 if the argument is 0; otherwise, it will return 0! If no argument is given, then 0 is returned! - -``` -(integer) yes <integer> -``` - -... always returns 1. The parameter is optional. Example: - -``` -# Prints out 1, because foo is not defined -if yes { say no defined foo; } -``` - -## Control statements - -Control statements available in Fype: - -``` -if <expression> { <statements> } -``` - -... runs the statements if the expression evaluates to a true value. - -``` -ifnot <expression> { <statements> } -``` - -... runs the statements if the expression evaluates to a false value. - -``` -while <expression> { <statements> } -``` - -... runs the statements as long as the expression evaluates to a true value. - -``` -until <expression> { <statements> } -``` - -... runs the statements as long as the expression evaluates to a false value. - -## Scopes - -A new scope starts with an { and ends with an }. An exception is a procedure, which does not use its own scope (see later in this manual). Control statements and functions support scopes. The "scope" function prints out all available symbols at the current scope. Here is a small example: - -``` -my foo = 1; - -{ - # Prints out 1 - put defined foo; - { - my bar = 2; - - # Prints out 1 - put defined bar; - - # Prints out all available symbols at this - # point to stdout. Those are: bar and foo - scope; - } - - # Prints out 0 - put defined bar; - - my baz = 3; -} - -# Prints out 0 -say defined bar; -``` - -Another example including an actual output: - -``` -./fype -e ’my global; func foo { my var4; func bar { my var2, var3; func baz { my var1; scope; } baz; } bar; } foo;’ -Scopes: -Scope stack size: 3 -Global symbols: -SYM_VARIABLE: global (id=00034, line=-0001, pos=-001, type=TT_INTEGER, dval=0.000000, refs=-1) -SYM_FUNCTION: foo -Local symbols: -SYM_VARIABLE: var1 (id=00038, line=-0001, pos=-001, type=TT_INTEGER, dval=0.000000, refs=-1) -1 level(s) up: -SYM_VARIABLE: var2 (id=00036, line=-0001, pos=-001, type=TT_INTEGER, dval=0.000000, refs=-1) -SYM_VARIABLE: var3 (id=00037, line=-0001, pos=-001, type=TT_INTEGER, dval=0.000000, refs=-1) -SYM_FUNCTION: baz -2 level(s) up: -SYM_VARIABLE: var4 (id=00035, line=-0001, pos=-001, type=TT_INTEGER, dval=0.000000, refs=-1) -SYM_FUNCTION: bar -``` - -## Definedness - -``` -(integer) defined <identifier> -``` - -... returns 1 if "identifier" has been defined. Returns 0 otherwise. - -``` -(integer) undef <identifier> -``` - -... tries to undefine/delete the "identifier". Returns 1 if it succeeded, otherwise 0 is returned. - -## System - -These are some system and interpreter specific built-in functions supported: - -``` -(void) end -``` - -... exits the program with the exit status of 0. - -``` -(void) exit <integer> -``` - -... exits the program with the specified exit status. - -``` -(integer) fork -``` - -... forks a subprocess. It returns 0 for the child process and the PID of the child process otherwise! Example: - -``` -my pid = fork; - -if pid { - put "I am the parent process; child has the pid "; - say pid; - -} ifnot pid { - say "I am the child process"; -} -``` - -To execute the garbage collector do: - -``` -(integer) GC -``` - -It returns the number of items freed! You may wonder why most of the time, it will produce a value of 0! Fype tries to free not needed memory ASAP. This may change in future versions to gain faster execution speed! - -### I/O - -``` -(any) put <any> -``` - -... prints out the argument - -``` -(any) say <any> -``` - -is the same as put, but also includes an ending newline. - -``` -(void) ln -``` - -... just prints a new line. - -## Procedures and functions - -### Procedures - -A procedure can be defined with the "proc" keyword and deleted with the "undef" keyword. A procedure does not return any value and does not support parameter passing. It's using already defined variables (e.g. global variables). A procedure does not have its own namespace. It's using the calling namespace. It is possible to define new variables inside of a procedure in the current namespace. - -``` -proc foo { - say 1 + a * 3 + b; - my c = 6; -} - -my a = 2, b = 4; - -foo; # Run the procedure. Print out "11\n" -say c; # Print out "6\n"; -``` - -### Nested procedures - -It's possible to define procedures inside of procedures. Since procedures don't have their own scope, nested procedures will be available to the current scope as soon as the main procedure has run the first time. You may use the "defined" keyword to check if a procedure has been defined or not. - -``` -proc foo { - say "I am foo"; - - undef bar; - proc bar { - say "I am bar"; - } -} - -# Here bar would produce an error because -# the proc is not yet defined! -# bar; - -foo; # Here the procedure foo will define the procedure bar! -bar; # Now the procedure bar is defined! -foo; # Here the procedure foo will redefine bar again! -``` - -### Functions - -A function can be defined with the "func" keyword and deleted with the "undef" keyword. Function do not yet return values and do not yet supports parameter passing. It's using local (lexical scoped) variables. If a certain variable does not exist, when It's using already defined variables (e.g. one scope above). - -``` -func foo { - say 1 + a * 3 + b; - my c = 6; -} - -my a = 2, b = 4; - -foo; # Run the procedure. Print out "11\n" -say c; # Will produce an error because c is out of scope! -``` - -### Nested functions - -Nested functions work the same way the nested procedures work, except that nested functions will not be available anymore after the function has been left! - -``` -func foo { - func bar { - say "Hello i am nested"; - } - - bar; # Calling nested -} - -foo; -bar; # Will produce an error because bar is out of scope! -``` - -## Arrays - -Some progress on arrays has been made too. The following example creates a multidimensional array "foo". Its first element is the return value of the func which is "bar". The fourth value is a string" 3" converted to a double number. The last element is an anonymous array which itself contains another anonymous array as its final element: - -``` -func bar { say ”bar” } -my foo = [bar, 1, 4/2, double ”3”, [”A”, [”BA”, ”BB”]]]; -say foo; -``` - -It produces the following output: - -``` -% ./fype arrays.fy -bar -01 -2 -3.000000 -A -BA -BB -``` - -## Fancy stuff - -Fancy stuff like OOP or Unicode or threading is not planed. But fancy stuff like function pointers and closures may be considered.:) - -## May the source be with you - -You can find all of this on the GitHub page. There is also an "examples" folders containing some Fype scripts! - -=> https://codeberg.org/snonux/fype - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2011-05-07-perl-daemon-service-framework.gmi.tpl.62ef757776fbb71d8e8117128b31b664f56d5c4fd0bcd6c62eca6994b9b1fa63 b/gemfeed/.rcmbackup/2011-05-07-perl-daemon-service-framework.gmi.tpl.62ef757776fbb71d8e8117128b31b664f56d5c4fd0bcd6c62eca6994b9b1fa63 deleted file mode 100644 index 8465297b..00000000 --- a/gemfeed/.rcmbackup/2011-05-07-perl-daemon-service-framework.gmi.tpl.62ef757776fbb71d8e8117128b31b664f56d5c4fd0bcd6c62eca6994b9b1fa63 +++ /dev/null @@ -1,169 +0,0 @@ -# Perl Daemon (Service Framework) - -> Published at 2011-05-07T22:26:02+01:00; Updated at 2021-05-07 - -PerlDaemon is a minimal daemon for Linux and other Unix like operating systems programmed in Perl. It is a minimal but pretty functional and fairly generic service framework. This means that it does not do anything useful other than providing a framework for starting, stopping, configuring and logging. To do something useful, a module (written in Perl) must be provided. - -``` - a'! _,,_ a'! _,,_ a'! _,,_ - \\_/ \ \\_/ \ \\_/ \.-, - \, /-( /'-,\, /-( /'-, \, /-( / - //\ //\\ //\ //\\ //\ //\\jrei -``` - -<< template::inline::toc - -## Features - -PerlDaemon supports: - -* Automatic daemonizing -* Logging -* log rotation (via SIGHUP) -* Clean shutdown support (SIGTERM) -* Pid file support (incl. check on startup) -* Easy to configure -* Easy to extend -* Multi-instance support (just use a different directory for each instance). - -## Quick Guide - -```sh -# Starting - ./bin/perldaemon start (or shortcut ./control start) - -# Stopping - ./bin/perldaemon stop (or shortcut ./control stop) - -# Alternatively: Starting in foreground -./bin/perldaemon start daemon.daemonize=no (or shortcut ./control foreground) -``` - -To stop a daemon from running in foreground mode, "Ctrl+C" must be hit. To see more available startup options run "./control" without any argument. - -## How to configure - -The daemon instance can be configured in "./conf/perldaemon.conf". If you want to change a property only once, it is also possible to specify it on the command line (which will take precedence over the config file). All available config properties can be displayed via "./control keys": - -```sh -pb@titania:~/svn/utils/perldaemon/trunk$ ./control keys -# Path to the logfile -daemon.logfile=./log/perldaemon.log - -# The amount of seconds until the next event look takes place -daemon.loopinterval=1 - -# Path to the modules dir -daemon.modules.dir=./lib/PerlDaemonModules - -# Specifies either the daemon should run in daemon or foreground mode -daemon.daemonize=yes - -# Path to the pidfile -daemon.pidfile=./run/perldaemon.pid - -# Each module should run every run interval seconds -daemon.modules.runinterval=3 - -# Path to the alive file (is touched every loop interval seconds, usable for monitoring) -daemon.alivefile=./run/perldaemon.alive - -# Specifies the working directory -daemon.wd=./ -``` - -## Example - -So let's start the daemon with a loop interval of 10 seconds: - -```sh -$ ./control keys | grep daemon.loopinterval -daemon.loopinterval=1 -$ ./control keys daemon.loopinterval=10 | grep daemon.loopinterval -daemon.loopinterval=10 -$ ./control start daemon.loopinterval=10; sleep 10; tail -n 2 log/perldaemon.log -Starting daemon now... -Mon Jun 13 11:29:27 2011 (PID 2838): Triggering PerlDaemonModules::ExampleModule -(last triggered before 10.002106s; carry: 7.002106s; wanted interval: 3s) -Mon Jun 13 11:29:27 2011 (PID 2838): ExampleModule Test 2 -$ ./control stop -Stopping daemon now... -``` - -If you want to change that property forever, either edit perldaemon.conf or do this: - -```sh -$ ./control keys daemon.loopinterval=10 > new.conf; mv new.conf conf/perldaemon.conf -``` - -## HiRes event loop - -PerlDaemon uses `Time::HiRes` to make sure that all the events run incorrect intervals. For each loop run, a time carry value is recorded and added to the next loop run to catch up on lost time. - -## Writing your own modules - -### Example module - -This is one of the example modules you will find in the source code. It should be pretty self-explanatory if you know Perl :-). - -```perl -package PerlDaemonModules::ExampleModule; - -use strict; -use warnings; - -sub new ($$$) { - my ($class, $conf) = @_; - - my $self = bless { conf => $conf }, $class; - - # Store some private module stuff - $self->{counter} = 0; - - return $self; -} - -# Runs periodically in a loop (set interval in perldaemon.conf) -sub do ($) { - my $self = shift; - my $conf = $self->{conf}; - my $logger = $conf->{logger}; - - # Calculate some private module stuff - my $count = ++$self->{counter}; - - $logger->logmsg("ExampleModule Test $count"); -} - -1; -``` - -### Your own module - -Want to give it some better use? It's just as easy as: - -```sh - cd ./lib/PerlDaemonModules/ - cp ExampleModule.pm YourModule.pm - vi YourModule.pm - cd - - ./bin/perldaemon restart (or shortcurt ./control restart) -``` - -Now watch `./log/perldaemon.log` closely. It is a good practice to test your modules in 'foreground mode' (see above how to do that). - -BTW: You can install as many modules within the same instance as desired. But they are run in sequential order (in future, they can also run in parallel using several threads or processes). - -## May the source be with you - -You can find PerlDaemon (including the examples) at: - -=> https://codeberg.org/snonux/perldaemon - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -Other related posts are: - -<< template::inline::rindex perl - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2015-12-05-run-debian-on-your-phone-with-debroid.gmi.tpl.6b6aaeb972eb69a3fae8630218bf7929803353053b21f20d55de72dec5e3d073 b/gemfeed/.rcmbackup/2015-12-05-run-debian-on-your-phone-with-debroid.gmi.tpl.6b6aaeb972eb69a3fae8630218bf7929803353053b21f20d55de72dec5e3d073 deleted file mode 100644 index 8b153366..00000000 --- a/gemfeed/.rcmbackup/2015-12-05-run-debian-on-your-phone-with-debroid.gmi.tpl.6b6aaeb972eb69a3fae8630218bf7929803353053b21f20d55de72dec5e3d073 +++ /dev/null @@ -1,180 +0,0 @@ -# Run Debian on your phone with Debroid - -> Published at 2015-12-05T16:12:57+00:00; Updated at 2021-05-16 - -You can use the following tutorial to install a full-blown Debian GNU/Linux Chroot on an LG G3 D855 CyanogenMod 13 (Android 6). First of all, you need to have root permissions on your phone, and you also need to have the developer mode activated. The following steps have been tested on Linux (Fedora 23). - -=> ./run-debian-on-your-phone-with-debroid/Deboroid.png - -A couple of years have passed since I last worked on Debroid. Currently, I am using the Termux app on Android, which is less sophisticated than a fully blown Debian installation but sufficient for my current requirements. The content of this site may be still relevant, and it would also work with more recent versions of Debian and Android. I would expect that some minor modifications need to be made, though. - -``` - ____ _ _ _ -| _ \ ___| |__ _ __ ___ (_) __| | -| | | |/ _ \ '_ \| '__/ _ \| |/ _` | -| |_| | __/ |_) | | | (_) | | (_| | -|____/ \___|_.__/|_| \___/|_|\__,_| - -``` - -<< template::inline::toc - -## Step by step guide - -All scripts mentioned here can be found on GitHub at: - -=> https://codeberg.org/snonux/debroid - -### First debootstrap stage - -This is to be performed on a Fedora Linux machine (could work on a Debian too, but Fedora is just what I use on my Laptop). The following steps prepare an initial Debian base image, which can then be transferred to the phone. - -```sh -sudo dnf install debootstrap -# 5g -dd if=/dev/zero of=jessie.img bs=$[ 1024 * 1024 ] \ - count=$[ 1024 * 5 ] - -# Show used loop devices -sudo losetup -f -# Store the next free one to $loop -loop=loopN -sudo losetup /dev/$loop jessie.img - -mkdir jessie -sudo mkfs.ext4 /dev/$loop -sudo mount /dev/$loop jessie -sudo debootstrap --foreign --variant=minbase \ - --arch armel jessie jessie/ \ - http://http.debian.net/debian -sudo umount jessie -``` - -### Copy Debian image to the phone - -Now setup the Debian image on an external SD card on the Phone via Android Debugger as follows: - -```sh -adb root && adb wait-for-device && adb shell -mkdir -p /storage/sdcard1/Linux/jessie -exit - -# Sparse image problem, may be too big for copying otherwise -gzip jessie.img -# Copy over -adb push jessie.img.gz /storage/sdcard1/Linux/jessie.img.gz -adb shell -cd /storage/sdcard1/Linux -gunzip jessie.img.gz - -# Show used loop devices -losetup -f -# Store the next free one to $loop -loop=loopN - -# Use the next free one (replace the loop number) -losetup /dev/block/$loop $(pwd)/jessie.img -mount -t ext4 /dev/block/$loop $(pwd)/jessie - -# Bind-Mound proc, dev, sys` -busybox mount --bind /proc $(pwd)/jessie/proc -busybox mount --bind /dev $(pwd)/jessie/dev -busybox mount --bind /dev/pts $(pwd)/jessie/dev/pts -busybox mount --bind /sys $(pwd)/jessie/sys - -# Bind-Mound the rest of Android -mkdir -p $(pwd)/jessie/storage/sdcard{0,1} -busybox mount --bind /storage/emulated \ - $(pwd)/jessie/storage/sdcard0 -busybox mount --bind /storage/sdcard1 \ - $(pwd)/jessie/storage/sdcard1 - -# Check mounts -mount | grep jessie -``` - -### Second debootstrap stage - -This is to be performed on the Android phone itself (inside a Debian chroot): - -```sh -chroot $(pwd)/jessie /bin/bash -l -export PATH=/bin:/usr/bin:/usr/local/bin:/sbin:/usr/sbin:/usr/local/sbin -/debootstrap/debootstrap --second-stage -exit # Leave chroot -exit # Leave adb shell -``` - -### Setup of various scripts - -jessie.sh deals with all the loopback mount magic and so on. It will be run later every time you start Debroid on your phone. - -```sh -# Install script jessie.sh -adb push storage/sdcard1/Linux/jessie.sh /storage/sdcard/Linux/jessie.sh -adb shell -cd /storage/sdcard1/Linux -sh jessie.sh enter - -# Bashrc -cat <<END >~/.bashrc -export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:$PATH -export EDITOR=vim -hostname $(cat /etc/hostname) -END - -# Fixing an error message while loading the profile -sed -i s#id#/usr/bin/id# /etc/profile - -# Setting the hostname -echo phobos > /etc/hostname -echo 127.0.0.1 phobos > /etc/hosts -hostname phobos - -# Apt-sources -cat <<END > sources.list -deb http://ftp.uk.debian.org/debian/ jessie main contrib non-free -deb-src http://ftp.uk.debian.org/debian/ jessie main contrib non-free -END -apt-get update -apt-get upgrade -apt-get dist-upgrade -exit # Exit chroot -``` - -### Entering Debroid and enable a service - -This enters Debroid on your phone and starts the example service uptimed: - -```sh -sh jessie.sh enter - -# Setup example serice uptimed -apt-get install uptimed -cat <<END > /etc/rc.debroid -export PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:$PATH -service uptimed status &>/dev/null || service uptimed start -exit 0 -END - -chmod 0755 /etc/rc.debroid -exit # Exit chroot -exit # Exit adb shell -``` - -### Include to Android startup: - -If you want to start Debroid automatically whenever your phone starts, then do the following: - -```sh -adb push data/local/userinit.sh /data/local/userinit.sh -adb shell -chmod +x /data/local/userinit.sh -exit -``` - -Reboot & test! Enjoy! - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2016-04-09-jails-and-zfs-on-freebsd-with-puppet.gmi.tpl.221f1043b07e8b62c50d3650714e4f5485d943e8015f956eefabf0ad617fe617 b/gemfeed/.rcmbackup/2016-04-09-jails-and-zfs-on-freebsd-with-puppet.gmi.tpl.221f1043b07e8b62c50d3650714e4f5485d943e8015f956eefabf0ad617fe617 deleted file mode 100644 index 75bb7ac3..00000000 --- a/gemfeed/.rcmbackup/2016-04-09-jails-and-zfs-on-freebsd-with-puppet.gmi.tpl.221f1043b07e8b62c50d3650714e4f5485d943e8015f956eefabf0ad617fe617 +++ /dev/null @@ -1,396 +0,0 @@ -# Jails and ZFS with Puppet on FreeBSD - -> Published at 2016-04-09T18:29:47+01:00 - -Over the last couple of years I wrote quite a few Puppet modules in order to manage my personal server infrastructure. One of them manages FreeBSD Jails and another one ZFS file systems. I thought I would give a brief overview in how it looks and feels. - -``` - __ __ - (( \---/ )) - )__ __( - / ()___() \ - \ /(_)\ / - \ \_|_/ / - _______> <_______ - //\ |>o<| /\\ - \\/___ ___\// - | | - | | - | | - | | - `--....---' - \ \ - \ `. hjw - \ `. -``` - -<< template::inline::toc - -## ZFS - -The ZFS module is a pretty basic one. It does not manage ZFS pools yet as I am not creating them often enough which would justify implementing an automation. But let's see how we can create a ZFS file system (on an already given ZFS pool named ztank): - -Puppet snippet: - -``` -zfs::create { 'ztank/foo': - ensure => present, - filesystem => '/srv/foo', - - require => File['/srv'], -} -``` - -Puppet run: - -``` -admin alphacentauri:/opt/git/server/puppet/manifests [1212]% puppet.apply -Password: -Info: Loading facts -Info: Loading facts -Info: Loading facts -Info: Loading facts -Notice: Compiled catalog for alphacentauri.home in environment production in 7.14 seconds -Info: Applying configuration version '1460189837' -Info: mount[files]: allowing * access -Info: mount[restricted]: allowing * access -Notice: /Stage[main]/Main/Node[alphacentauri]/Zfs::Create[ztank/foo]/Exec[ztank/foo_create]/returns: executed successfully -Notice: Finished catalog run in 25.41 seconds -admin alphacentauri:~ [1213]% zfs list | grep foo -ztank/foo 96K 1.13T 96K /srv/foo -admin alphacentauri:~ [1214]% df | grep foo -ztank/foo 1214493520 96 1214493424 0% /srv/foo -admin alphacentauri:~ [1215]% -``` - -The destruction of the file system just requires to set "ensure" to "absent" in Puppet: - -``` -zfs::create { 'ztank/foo': - ensure => absent, - filesystem => '/srv/foo', - - require => File['/srv'], -}¬ -``` - -Puppet run: - -``` -admin alphacentauri:/opt/git/server/puppet/manifests [1220]% puppet.apply -Password: -Info: Loading facts -Info: Loading facts -Info: Loading facts -Info: Loading facts -Notice: Compiled catalog for alphacentauri.home in environment production in 6.14 seconds -Info: Applying configuration version '1460190203' -Info: mount[files]: allowing * access -Info: mount[restricted]: allowing * access -Notice: /Stage[main]/Main/Node[alphacentauri]/Zfs::Create[ztank/foo]/Exec[zfs destroy -r ztank/foo]/returns: executed successfully -Notice: Finished catalog run in 22.72 seconds -admin alphacentauri:/opt/git/server/puppet/manifests [1221]% zfs list | grep foo -zsh: done zfs list | -zsh: exit 1 grep foo -admin alphacentauri:/opt/git/server/puppet/manifests [1222:1]% df | grep foo -zsh: done df | -zsh: exit 1 grep foo -``` - -## Jails - -Here is an example in how a FreeBSD Jail can be created. The Jail will have its own public IPv6 address. And it will have its own internal IPv4 address with IPv4 NAT to the internet (this is due to the limitation that the host server only got one public IPv4 address which requires sharing between all the Jails). - -Furthermore, Puppet will ensure that the Jail will have its own ZFS file system (internally it is using the ZFS module). Please notice that the NAT requires the packet filter to be setup correctly (not covered in this blog post). - -``` -include jail::freebsd - -# Cloned interface for Jail IPv4 NAT -freebsd::rc_config { 'cloned_interfaces': - value => 'lo1', -} -freebsd::rc_config { 'ipv4_addrs_lo1': - value => '192.168.0.1-24/24' -} - -freebsd::ipalias { '2a01:4f8:120:30e8::17': - ensure => up, - proto => 'inet6', - preflen => '64', - interface => 're0', - aliasnum => '8', -} - -class { 'jail': - ensure => present, - jails_config => { - sync => { - '_ensure' => present, - '_type' => 'freebsd', - '_mirror' => 'ftp://ftp.de.freebsd.org', - '_remote_path' => 'FreeBSD/releases/amd64/10.1-RELEASE', - '_dists' => [ 'base.txz', 'doc.txz', ], - '_ensure_directories' => [ '/opt', '/opt/enc' ], - '_ensure_zfs' => [ '/sync' ], - 'host.hostname' => "'sync.ian.buetow.org'", - 'ip4.addr' => '192.168.0.17', - 'ip6.addr' => '2a01:4f8:120:30e8::17', - }, - } -} -``` - -This is how the result looks like: - -``` -admin sun:/etc [1939]% puppet.apply -Info: Loading facts -Info: Loading facts -Info: Loading facts -Info: Loading facts -Notice: Compiled catalog for sun.ian.buetow.org in environment production in 1.80 seconds -Info: Applying configuration version '1460190986' -Notice: /Stage[main]/Jail/File[/etc/jail.conf]/ensure: created -Info: mount[files]: allowing * access -Info: mount[restricted]: allowing * access -Info: Computing checksum on file /etc/motd -Info: /Stage[main]/Motd/File[/etc/motd]: Filebucketed /etc/motd to puppet with sum fced1b6e89f50ef2c40b0d7fba9defe8 -Notice: /Stage[main]/Jail/Jail::Create[sync]/File[/jail/sync]/ensure: created -Notice: /Stage[main]/Jail/Jail::Create[sync]/Zfs::Create[zroot/jail/sync]/Exec[zroot/jail/sync_create]/returns: executed successfully -Notice: /Stage[main]/Jail/Jail::Create[sync]/File[/jail/sync/opt]/ensure: created -Notice: /Stage[main]/Jail/Jail::Create[sync]/File[/jail/sync/opt/enc]/ensure: created -Notice: /Stage[main]/Jail/Jail::Create[sync]/Jail::Ensure_zfs[/sync]/Zfs::Create[zroot/jail/sync/sync]/Exec[zroot/jail/sync/sync_create]/returns: executed successfully -Notice: /Stage[main]/Jail/Jail::Create[sync]/Jail::Freebsd::Create[sync]/File[/jail/sync/.jailbootstrap]/ensure: created -Notice: /Stage[main]/Jail/Jail::Create[sync]/Jail::Freebsd::Create[sync]/File[/etc/fstab.jail.sync]/ensure: created -Notice: /Stage[main]/Jail/Jail::Create[sync]/Jail::Freebsd::Create[sync]/File[/jail/sync/.jailbootstrap/bootstrap.sh]/ensure: created -Notice: /Stage[main]/Jail/Jail::Create[sync]/Jail::Freebsd::Create[sync]/Exec[sync_bootstrap]/returns: executed successfully -Notice: Finished catalog run in 49.72 seconds -admin sun:/etc [1942]% ls -l /jail/sync -total 154 --r--r--r-- 1 root wheel 6198 11 Nov 2014 COPYRIGHT -drwxr-xr-x 2 root wheel 47 11 Nov 2014 bin -drwxr-xr-x 7 root wheel 43 11 Nov 2014 boot -dr-xr-xr-x 2 root wheel 2 11 Nov 2014 dev -drwxr-xr-x 23 root wheel 101 9 Apr 10:37 etc -drwxr-xr-x 3 root wheel 50 11 Nov 2014 lib -drwxr-xr-x 3 root wheel 4 11 Nov 2014 libexec -drwxr-xr-x 2 root wheel 2 11 Nov 2014 media -drwxr-xr-x 2 root wheel 2 11 Nov 2014 mnt -drwxr-xr-x 3 root wheel 3 9 Apr 10:36 opt -dr-xr-xr-x 2 root wheel 2 11 Nov 2014 proc -drwxr-xr-x 2 root wheel 143 11 Nov 2014 rescue -drwxr-xr-x 2 root wheel 6 11 Nov 2014 root -drwxr-xr-x 2 root wheel 132 11 Nov 2014 sbin -drwxr-xr-x 2 root wheel 2 9 Apr 10:36 sync -lrwxr-xr-x 1 root wheel 11 11 Nov 2014 sys -> usr/src/sys -drwxrwxrwt 2 root wheel 2 11 Nov 2014 tmp -drwxr-xr-x 14 root wheel 14 11 Nov 2014 usr -drwxr-xr-x 24 root wheel 24 11 Nov 2014 var -admin sun:/etc [1943]% zfs list | grep sync;df | grep sync -zroot/jail/sync 162M 343G 162M /jail/sync -zroot/jail/sync/sync 144K 343G 144K /jail/sync/sync -/opt/enc 5061624 84248 4572448 2% /jail/sync/opt/enc -zroot/jail/sync 360214972 166372 360048600 0% /jail/sync -zroot/jail/sync/sync 360048744 144 360048600 0% /jail/sync/sync -admin sun:/etc [1944]% cat /etc/fstab.jail.sync -# Generated by Puppet for a Jail. -# Can contain file systems to be mounted curing jail start. -admin sun:/etc [1945]% cat /etc/jail.conf -# Generated by Puppet - -allow.chflags = true; -exec.start = '/bin/sh /etc/rc'; -exec.stop = '/bin/sh /etc/rc.shutdown'; -mount.devfs = true; -mount.fstab = "/etc/fstab.jail.$name"; -path = "/jail/$name"; - -sync { - host.hostname = 'sync.ian.buetow.org'; - ip4.addr = 192.168.0.17; - ip6.addr = 2a01:4f8:120:30e8::17; -} -admin sun:/etc [1955]% sudo service jail start sync -Password: -Starting jails: sync. -admin sun:/etc [1956]% jls | grep sync - 103 192.168.0.17 sync.ian.buetow.org /jail/sync -admin sun:/etc [1957]% sudo jexec 103 /bin/csh -root@sync:/ # ifconfig -a -re0: flags=8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> metric 0 mtu 1500 - options=8209b<RXCSUM,TXCSUM,VLAN_MTU,VLAN_HWTAGGING,VLAN_HWCSUM,WOL_MAGIC,LINKSTATE> - ether 50:46:5d:9f:fd:1e - inet6 2a01:4f8:120:30e8::17 prefixlen 64 - nd6 options=8021<PERFORMNUD,AUTO_LINKLOCAL,DEFAULTIF> - media: Ethernet autoselect (1000baseT <full-duplex>) - status: active -lo0: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 - options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6> - nd6 options=21<PERFORMNUD,AUTO_LINKLOCAL> - lo1: flags=8049<UP,LOOPBACK,RUNNING,MULTICAST> metric 0 mtu 16384 - options=600003<RXCSUM,TXCSUM,RXCSUM_IPV6,TXCSUM_IPV6> - inet 192.168.0.17 netmask 0xffffffff - nd6 options=29<PERFORMNUD,IFDISABLED,AUTO_LINKLOCAL> -``` - -## Inside-Jail Puppet - -To automatically setup the applications running in the Jail I am using Puppet as well. I wrote a few scripts which bootstrap Puppet inside of a newly created Jail. It is doing the following: - -* Mounts an encrypted container (containing a secret Puppet manifests [git repository]) -* Activates "pkg-ng", the FreeBSD binary package manager, in the Jail -* Installs Puppet plus all dependencies in the Jail -* Updates the Jail via "freebsd-update" to the latest version -* Restarts the Jail and invokes Puppet. -* Puppet then also schedules a periodic cron job for the next Puppet runs. - -``` -admin sun:~ [1951]% sudo /opt/snonux/local/etc/init.d/enc activate sync -Starting jails: dns. -The package management tool is not yet installed on your system. -Do you want to fetch and install it now? [y/N]: y -Bootstrapping pkg from pkg+http://pkg.FreeBSD.org/freebsd:10:x86:64/latest, please wait... -Verifying signature with trusted certificate pkg.freebsd.org.2013102301... done -[sync.ian.buetow.org] Installing pkg-1.7.2... -[sync.ian.buetow.org] Extracting pkg-1.7.2: 100% -Updating FreeBSD repository catalogue... -[sync.ian.buetow.org] Fetching meta.txz: 100% 944 B 0.9kB/s 00:01 -[sync.ian.buetow.org] Fetching packagesite.txz: 100% 5 MiB 5.6MB/s 00:01 -Processing entries: 100% -FreeBSD repository update completed. 25091 packages processed. -Updating database digests format: 100% -The following 20 package(s) will be affected (of 0 checked): - - New packages to be INSTALLED: - git: 2.7.4_1 - expat: 2.1.0_3 - python27: 2.7.11_1 - libffi: 3.2.1 - indexinfo: 0.2.4 - gettext-runtime: 0.19.7 - p5-Error: 0.17024 - perl5: 5.20.3_9 - cvsps: 2.1_1 - p5-Authen-SASL: 2.16_1 - p5-Digest-HMAC: 1.03_1 - p5-GSSAPI: 0.28_1 - curl: 7.48.0_1 - ca_root_nss: 3.22.2 - p5-Net-SMTP-SSL: 1.03 - p5-IO-Socket-SSL: 2.024 - p5-Net-SSLeay: 1.72 - p5-IO-Socket-IP: 0.37 - p5-Socket: 2.021 - p5-Mozilla-CA: 20160104 - - The process will require 144 MiB more space. - 30 MiB to be downloaded. -[sync.ian.buetow.org] Fetching git-2.7.4_1.txz: 100% 4 MiB 3.7MB/s 00:01 -[sync.ian.buetow.org] Fetching expat-2.1.0_3.txz: 100% 98 KiB 100.2kB/s 00:01 -[sync.ian.buetow.org] Fetching python27-2.7.11_1.txz: 100% 10 MiB 10.7MB/s 00:01 -[sync.ian.buetow.org] Fetching libffi-3.2.1.txz: 100% 35 KiB 36.2kB/s 00:01 -[sync.ian.buetow.org] Fetching indexinfo-0.2.4.txz: 100% 5 KiB 5.0kB/s 00:01 -[sync.ian.buetow.org] Fetching gettext-runtime-0.19.7.txz: 100% 148 KiB 151.1kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-Error-0.17024.txz: 100% 24 KiB 24.8kB/s 00:01 -[sync.ian.buetow.org] Fetching perl5-5.20.3_9.txz: 100% 13 MiB 6.9MB/s 00:02 -[sync.ian.buetow.org] Fetching cvsps-2.1_1.txz: 100% 41 KiB 42.1kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-Authen-SASL-2.16_1.txz: 100% 44 KiB 45.1kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-Digest-HMAC-1.03_1.txz: 100% 9 KiB 9.5kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-GSSAPI-0.28_1.txz: 100% 41 KiB 41.7kB/s 00:01 -[sync.ian.buetow.org] Fetching curl-7.48.0_1.txz: 100% 2 MiB 2.2MB/s 00:01 -[sync.ian.buetow.org] Fetching ca_root_nss-3.22.2.txz: 100% 324 KiB 331.4kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-Net-SMTP-SSL-1.03.txz: 100% 11 KiB 10.8kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-IO-Socket-SSL-2.024.txz: 100% 153 KiB 156.4kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-Net-SSLeay-1.72.txz: 100% 234 KiB 239.3kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-IO-Socket-IP-0.37.txz: 100% 27 KiB 27.4kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-Socket-2.021.txz: 100% 37 KiB 38.0kB/s 00:01 -[sync.ian.buetow.org] Fetching p5-Mozilla-CA-20160104.txz: 100% 147 KiB 150.8kB/s 00:01 -Checking integrity... -[sync.ian.buetow.org] [1/12] Installing libyaml-0.1.6_2... -[sync.ian.buetow.org] [1/12] Extracting libyaml-0.1.6_2: 100% -[sync.ian.buetow.org] [2/12] Installing libedit-3.1.20150325_2... -[sync.ian.buetow.org] [2/12] Extracting libedit-3.1.20150325_2: 100% -[sync.ian.buetow.org] [3/12] Installing ruby-2.2.4,1... -[sync.ian.buetow.org] [3/12] Extracting ruby-2.2.4,1: 100% -[sync.ian.buetow.org] [4/12] Installing ruby22-gems-2.6.2... -[sync.ian.buetow.org] [4/12] Extracting ruby22-gems-2.6.2: 100% -[sync.ian.buetow.org] [5/12] Installing libxml2-2.9.3... -[sync.ian.buetow.org] [5/12] Extracting libxml2-2.9.3: 100% -[sync.ian.buetow.org] [6/12] Installing dmidecode-3.0... -[sync.ian.buetow.org] [6/12] Extracting dmidecode-3.0: 100% -[sync.ian.buetow.org] [7/12] Installing rubygem-json_pure-1.8.3... -[sync.ian.buetow.org] [7/12] Extracting rubygem-json_pure-1.8.3: 100% -[sync.ian.buetow.org] [8/12] Installing augeas-1.4.0... -[sync.ian.buetow.org] [8/12] Extracting augeas-1.4.0: 100% -[sync.ian.buetow.org] [9/12] Installing rubygem-facter-2.4.4... -[sync.ian.buetow.org] [9/12] Extracting rubygem-facter-2.4.4: 100% -[sync.ian.buetow.org] [10/12] Installing rubygem-hiera1-1.3.4_1... -[sync.ian.buetow.org] [10/12] Extracting rubygem-hiera1-1.3.4_1: 100% -[sync.ian.buetow.org] [11/12] Installing rubygem-ruby-augeas-0.5.0_2... -[sync.ian.buetow.org] [11/12] Extracting rubygem-ruby-augeas-0.5.0_2: 100% -[sync.ian.buetow.org] [12/12] Installing puppet38-3.8.4_1... -===> Creating users and/or groups. -Creating group 'puppet' with gid '814'. -Creating user 'puppet' with uid '814'. -[sync.ian.buetow.org] [12/12] Extracting puppet38-3.8.4_1: 100% -. -. -. -. -. -Looking up update.FreeBSD.org mirrors... 4 mirrors found. -Fetching public key from update4.freebsd.org... done. -Fetching metadata signature for 10.1-RELEASE from update4.freebsd.org... done. -Fetching metadata index... done. -Fetching 2 metadata files... done. -Inspecting system... done. -Preparing to download files... done. -Fetching 874 patches.....10....20....30.... -. -. -. -Applying patches... done. -Fetching 1594 files... -Installing updates... -done. -Info: Loading facts -Info: Loading facts -Info: Loading facts -Info: Loading facts -Could not retrieve fact='pkgng_version', resolution='<anonymous>': undefined method `pkgng_enabled' for Facter:Module -Warning: Config file /usr/local/etc/puppet/hiera.yaml not found, using Hiera defaults -Notice: Compiled catalog for sync.ian.buetow.org in environment production in 1.31 seconds -Warning: Found multiple default providers for package: pkgng, gem, pip; using pkgng -Info: Applying configuration version '1460192563' -Notice: /Stage[main]/S_base_freebsd/User[root]/shell: shell changed '/bin/csh' to '/bin/tcsh' -Notice: /Stage[main]/S_user::Root_files/S_user::All_files[root_user]/File[/root/user]/ensure: created -Notice: /Stage[main]/S_user::Root_files/S_user::My_files[root]/File[/root/userfiles]/ensure: created -Notice: /Stage[main]/S_user::Root_files/S_user::My_files[root]/File[/root/.task]/ensure: created -. -. -. -. -Notice: Finished catalog run in 206.09 seconds -``` - -## Managing multiple Jails - -Of course I am operating multiple Jails on the same host this way with Puppet: - -* A Jail for the MTA -* A Jail for the Webserver -* A Jail for BIND DNS server -* A Jail for syncing data forth and back between various servers -* A Jail for other personal (experimental) use -* ...etc - -All done in a pretty automated manor. - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -Other *BSD related posts are: - -<< template::inline::rindex bsd - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2016-05-22-spinning-up-my-own-authoritative-dns-servers.gmi.tpl.ae0939420799accbfb4991d23cd55cf95cc1d66fc0abd0db147a8478d3a2177c b/gemfeed/.rcmbackup/2016-05-22-spinning-up-my-own-authoritative-dns-servers.gmi.tpl.ae0939420799accbfb4991d23cd55cf95cc1d66fc0abd0db147a8478d3a2177c deleted file mode 100644 index 39415e69..00000000 --- a/gemfeed/.rcmbackup/2016-05-22-spinning-up-my-own-authoritative-dns-servers.gmi.tpl.ae0939420799accbfb4991d23cd55cf95cc1d66fc0abd0db147a8478d3a2177c +++ /dev/null @@ -1,239 +0,0 @@ -# Spinning up my own authoritative DNS servers - -> Published at 2016-05-22T18:59:01+01:00 - -Finally, I had time to deploy my authoritative DNS servers (master and slave) for my domains "buetow.org" and "buetow.zone". My domain name provider is Schlund Technologies. They allow their customers to edit the DNS records (BIND files) manually. And they also allow you to set your authoritative DNS servers for your domains. From now, I am making use of that option. - -=> http://www.schlundtech.de Schlund Technologies - -<< template::inline::toc - -## All FreeBSD Jails - -To set up my authoritative DNS servers, I installed a FreeBSD Jail dedicated for DNS with Puppet on my root machine as follows: - -``` -include freebsd - -freebsd::ipalias { '2a01:4f8:120:30e8::14': - ensure => up, - proto => 'inet6', - preflen => '64', - interface => 're0', - aliasnum => '5', -} - -include jail::freebsd - -class { 'jail': - ensure => present, - jails_config => { - dns => { - '_ensure' => present, - '_type' => 'freebsd', - '_mirror' => 'ftp://ftp.de.freebsd.org', - '_remote_path' => 'FreeBSD/releases/amd64/10.1-RELEASE', - '_dists' => [ 'base.txz', 'doc.txz', ], - '_ensure_directories' => [ '/opt', '/opt/enc' ], - 'host.hostname' => "'dns.ian.buetow.org'", - 'ip4.addr' => '192.168.0.15', - 'ip6.addr' => '2a01:4f8:120:30e8::15', - }, - . - . - } -} -``` - -## PF firewall - -Please note that "dns.ian.buetow.org" is just the Jail name of the master DNS server (and "caprica.ian.buetow.org" the name of the Jail for the slave DNS server) and that I am using the DNS names "dns1.buetow.org" (master) and "dns2.buetow.org" (slave) for the actual service names (these are the DNS servers visible to the public). Please also note that the IPv4 address is an internal one. I have a PF to use NAT and PAT. The DNS ports are being forwarded (TCP and UDP) to that Jail. By default, all ports are blocked, so I am adding an exception rule for the IPv6 address. These are the PF rules in use: - -``` -% cat /etc/pf.conf -. -. -# dns.ian.buetow.org -rdr pass on re0 proto tcp from any to $pub_ip port {53} -> 192.168.0.15 -rdr pass on re0 proto udp from any to $pub_ip port {53} -> 192.168.0.15 -pass in on re0 inet6 proto tcp from any to 2a01:4f8:120:30e8::15 port {53} flags S/SA keep state -pass in on re0 inet6 proto udp from any to 2a01:4f8:120:30e8::15 port {53} flags S/SA keep state -. -. -``` - -## Puppet managed BIND zone files - -In "manifests/dns.pp" (the Puppet manifest for the Master DNS Jail itself), I configured the BIND DNS server this way: - -``` -class { 'bind_freebsd': - config => "puppet:///files/bind/named.${::hostname}.conf", - dynamic_config => "puppet:///files/bind/dynamic.${::hostname}", -} -``` - -The Puppet module is a pretty simple one. It installs the file "/usr/local/etc/named/named.conf" and it populates the "/usr/local/etc/named/dynamicdb" directory with all my zone files. - -Once (Puppet-) applied inside of the Jail, I get this: - -``` -paul uranus:~/git/blog/source [4268]% ssh admin@dns1.buetow.org.buetow.org pgrep -lf named -60748 /usr/local/sbin/named -u bind -c /usr/local/etc/namedb/named.conf -paul uranus:~/git/blog/source [4269]% ssh admin@dns1.buetow.org.buetow.org tail -n 13 /usr/local/etc/namedb/named.conf -zone "buetow.org" { - type master; - notify yes; - allow-update { key "buetoworgkey"; }; - file "/usr/local/etc/namedb/dynamic/buetow.org"; -}; - -zone "buetow.zone" { - type master; - notify yes; - allow-update { key "buetoworgkey"; }; - file "/usr/local/etc/namedb/dynamic/buetow.zone"; -}; -paul uranus:~/git/blog/source [4277]% ssh admin@dns1.buetow.org.buetow.org cat /usr/local/etc/namedb/dynamic/buetow.org -$TTL 3600 -@ IN SOA dns1.buetow.org. domains.buetow.org. ( - 25 ; Serial - 604800 ; Refresh - 86400 ; Retry - 2419200 ; Expire - 604800 ) ; Negative Cache TTL -; Infrastructure domains -@ IN NS dns1 -@ IN NS dns2 -* 300 IN CNAME web.ian -buetow.org. 86400 IN A 78.46.80.70 -buetow.org. 86400 IN AAAA 2a01:4f8:120:30e8:0:0:0:11 -buetow.org. 86400 IN MX 10 mail.ian -dns1 86400 IN A 78.46.80.70 -dns1 86400 IN AAAA 2a01:4f8:120:30e8:0:0:0:15 -dns2 86400 IN A 164.177.171.32 -dns2 86400 IN AAAA 2a03:2500:1:6:20:: -. -. -. -. -``` - -That is my master DNS server. My slave DNS server runs in another Jail on another bare-metal machine. Everything is set up similar to the master DNS server. However, that server is located in a different DC and different IP subnets. The only difference is the "named.conf". It's configured to be a slave, and that means that the "dynamicdb" gets populated by BIND itself while doing zone transfers from the master. - -``` -paul uranus:~/git/blog/source [4279]% ssh admin@dns2.buetow.org tail -n 11 /usr/local/etc/namedb/named.conf -zone "buetow.org" { - type slave; - masters { 78.46.80.70; }; - file "/usr/local/etc/namedb/dynamic/buetow.org"; -}; - -zone "buetow.zone" { - type slave; - masters { 78.46.80.70; }; - file "/usr/local/etc/namedb/dynamic/buetow.zone"; -}; -``` - -## The result - -The result looks like this now: - -``` -% dig -t ns buetow.org -; <<>> DiG 9.10.3-P4-RedHat-9.10.3-12.P4.fc23 <<>> -t ns buetow.org -;; global options: +cmd -;; Got answer: -;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 37883 -;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1 - -;; OPT PSEUDOSECTION: -; EDNS: version: 0, flags:; udp: 512 -;; QUESTION SECTION: -;buetow.org. IN NS - -;; ANSWER SECTION: -buetow.org. 600 IN NS dns2.buetow.org. -buetow.org. 600 IN NS dns1.buetow.org. - -;; Query time: 41 msec -;; SERVER: 192.168.1.254#53(192.168.1.254) -;; WHEN: Sun May 22 11:34:11 BST 2016 -;; MSG SIZE rcvd: 77 - -% dig -t any buetow.org @dns1.buetow.org -; <<>> DiG 9.10.3-P4-RedHat-9.10.3-12.P4.fc23 <<>> -t any buetow.org @dns1.buetow.org -;; global options: +cmd -;; Got answer: -;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 49876 -;; flags: qr aa rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 7 - -;; OPT PSEUDOSECTION: -; EDNS: version: 0, flags:; udp: 4096 -;; QUESTION SECTION: -;buetow.org. IN ANY - -;; ANSWER SECTION: -buetow.org. 86400 IN A 78.46.80.70 -buetow.org. 86400 IN AAAA 2a01:4f8:120:30e8::11 -buetow.org. 86400 IN MX 10 mail.ian.buetow.org. -buetow.org. 3600 IN SOA dns1.buetow.org. domains.buetow.org. 25 604800 86400 2419200 604800 -buetow.org. 3600 IN NS dns2.buetow.org. -buetow.org. 3600 IN NS dns1.buetow.org. - -;; ADDITIONAL SECTION: -mail.ian.buetow.org. 86400 IN A 78.46.80.70 -dns1.buetow.org. 86400 IN A 78.46.80.70 -dns2.buetow.org. 86400 IN A 164.177.171.32 -mail.ian.buetow.org. 86400 IN AAAA 2a01:4f8:120:30e8::12 -dns1.buetow.org. 86400 IN AAAA 2a01:4f8:120:30e8::15 -dns2.buetow.org. 86400 IN AAAA 2a03:2500:1:6:20:: - -;; Query time: 42 msec -;; SERVER: 78.46.80.70#53(78.46.80.70) -;; WHEN: Sun May 22 11:34:41 BST 2016 -;; MSG SIZE rcvd: 322 -``` - -## Monitoring - -For monitoring, I am using Icinga2 (I am operating two Icinga2 instances in two different DCs). I may have to post another blog article about Icinga2, but to get the idea, these were the snippets added to my Icinga2 configuration: - -``` -apply Service "dig" { - import "generic-service" - - check_command = "dig" - vars.dig_lookup = "buetow.org" - vars.timeout = 30 - - assign where host.name == "dns.ian.buetow.org" || host.name == "caprica.ian.buetow.org" -} - -apply Service "dig6" { - import "generic-service" - - check_command = "dig" - vars.dig_lookup = "buetow.org" - vars.timeout = 30 - vars.check_ipv6 = true - - assign where host.name == "dns.ian.buetow.org" || host.name == "caprica.ian.buetow.org" -} -``` - -## DNS update workflow - -Whenever I have to change a DNS entry, all I have to do is: - -* Git clone or update the Puppet repository -* Update/commit and push the zone file (e.g. "buetow.org") -* Wait for Puppet. Puppet will deploy that updated zone file. And it will reload the BIND server. -* The BIND server will notify all slave DNS servers (at the moment, only one). And it will transfer the new version of the zone. - -That's much more comfortable now than manually clicking at some web UIs at Schlund Technologies. - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2018-06-01-realistic-load-testing-with-ioriot-for-linux.gmi.tpl.7f5d7ea30eb225959a1d09327d0bcc8e2e2ecae80760ebb0d4341338c4aecf55 b/gemfeed/.rcmbackup/2018-06-01-realistic-load-testing-with-ioriot-for-linux.gmi.tpl.7f5d7ea30eb225959a1d09327d0bcc8e2e2ecae80760ebb0d4341338c4aecf55 deleted file mode 100644 index 2fdea893..00000000 --- a/gemfeed/.rcmbackup/2018-06-01-realistic-load-testing-with-ioriot-for-linux.gmi.tpl.7f5d7ea30eb225959a1d09327d0bcc8e2e2ecae80760ebb0d4341338c4aecf55 +++ /dev/null @@ -1,191 +0,0 @@ -# Realistic load testing with I/O Riot for Linux - -> Published at 2018-06-01T14:50:29+01:00; Updated at 2021-05-08 - -This text first was published in the german IT-Administrator computer Magazine. 3 years have passed since and I decided to publish it on my blog too. - -=> https://www.admin-magazin.de/Das-Heft/2018/06/Realistische-Lasttests-mit-I-O-Riot - -I havn't worked on I/O Riot for some time now, but all what is written here is still valid. I am still using I/O Riot to debug I/O issues and pattern once in a while, so by all means the tool is not obsolete yet. The tool even helped to resolve a major production incident at work caused by disk I/O. - -I am eagerly looking forward to revamp I/O Riot so that it uses the new BPF Linux capabilities instead of plain old Systemtap (or alternatively: Newer versions of Systemtap can also use BPF as the backend I have learned). Also, when I wrote I/O Riot initially, I didn't have any experience with the Go programming language yet and therefore I wrote it in C. Once it gets revamped I might consider using Go instead of C as it would spare me from many segmentation faults and headaches during development ;-). I might also just stick to C for plain performance reasons and just refactor the code dealing with concurrency. - -Pleace notice that some of the screenshots show the command "ioreplay" instead of "ioriot". That's because the name has changed after taking those. - -``` - .---. - / \ - \.@-@./ - /`\_/`\ - // _ \\ - | \ )|_ - /`\_`> <_/ \ -jgs\__/'---'\__/ -``` - -<< template::inline::toc - -# The article - -With I/O Riot IT administrators can load test and optimize the I/O subsystem of Linux-based operating systems. The tool makes it possible to record I/O patterns and replay them at a later time as often as desired. This means bottlenecks can be reproduced and eradicated. - -When storing huge amounts of data, such as more than 200 billion archived emails at Mimecast, it's not only the available storage capacity that matters, but also the data throughput and latency. At the same time, operating costs must be kept as low as possible. The more systems involved, the more important it is to optimize the hardware, the operating system and the applications running on it. - -## Background: Existing Techniques - -Conventional I/O benchmarking: Administrators usually use open source benchmarking tools like IOZone and bonnie++. Available database systems such as Redis and MySQL come with their own benchmarking tools. The common problem with these tools is that they work with prescribed artificial I/O patterns. Although this can test both sequential and randomized data access, the patterns do not correspond to what can be found on production systems. - -Testing by load test environment: Another option is to use a separate load test environment in which, as far as possible, a production environment with all its dependencies is simulated. However, an environment consisting of many microservices is very complex. Microservices are usually managed by different teams, which means extra coordination effort for each load test. Another challenge is to generate the load as authentically as possible so that the patterns correspond to a productive environment. Such a load test environment can only handle as many requests as its weakest link can handle. For example, load generators send many read and write requests to a frontend microservice, whereby the frontend forwards the requests to a backend microservice responsible for storing the data. If the frontend service does not process the requests efficiently enough, the backend service is not well utilized in the first place. As a rule, all microservices are clustered across many servers, which makes everything even more complicated. Under all these conditions it is very difficult to test I/O of separate backend systems. Moreover, for many small and medium-sized companies, a separate load test environment would not be feasible for cost reasons. - -Testing in the production environment: For these reasons, benchmarks are often carried out in the production environment. In order to derive value from this such tests are especially performed during peak hours when systems are under high load. However, testing on production systems is associated with risks and can lead to failure or loss of data without adequate protection. - -## Benchmarking the Email Cloud at Mimecast - -For email archiving, Mimecast uses an internally developed microservice, which is operated directly on Linux-based storage systems. A storage cluster is divided into several replication volumes. Data is always replicated three times across two secure data centers. Customer data is automatically allocated to one or more volumes, depending on throughput, so that all volumes are automatically assigned the same load. Customer data is archived on conventional, but inexpensive hard disks with several terabytes of storage capacity each. I/O benchmarking proved difficult for all the reasons mentioned above. Furthermore, there are no ready-made tools for this purpose in the case of self-developed software. The service operates on many block devices simultaneously, which can make the RAID controller a bottleneck. None of the freely available benchmarking tools can test several block devices at the same time without extra effort. In addition, emails typically consist of many small files. Randomized access to many small files is particularly inefficient. In addition to many software adaptations, the hardware and operating system must also be optimized. - -Mimecast encourages employees to be innovative and pursue their own ideas in the form of an internal competition, Pet Project. The goal of the pet project I/O Riot was to simplify OS and hardware level I/O benchmarking. The first prototype of I/O Riot was awarded an internal roadmap prize in the spring of 2017. A few months later, I/O Riot was used to reduce write latency in the storage clusters by about 50%. The improvement was first verified by I/O replay on a test system and then successively applied to all storage systems. I/O Riot was also used to resolve a production incident caused by disk I/O load. - -## Using I/O Riot - -First, all I/O events are logged to a file on a production system with I/O Riot. It is then copied to a test system where all events are replayed in the same way. The crucial point here is that you can reproduce I/O patterns as they are found on a production system as often as you like on a test system. This results in the possibility of optimizing the set screws on the system after each run. - -### Installation - -I/O Riot was tested under CentOS 7.2 x86_64. For compiling, the GNU C compiler and Systemtap including kernel debug information are required. Other Linux distributions are theoretically compatible but untested. First of all, you should update the systems involved as follows: - -``` -% sudo yum update -``` - -If the kernel is updated, please restart the system. The installation would be done without a restart but this would complicate the installation. The installed kernel version should always correspond to the currently running kernel. You can then install I/O Riot as follows: - -``` -% sudo yum install gcc git systemtap yum-utils kernel-devel-$(uname -r) -% sudo debuginfo-install kernel-$(uname -r) -% git clone https://github.com/mimecast/ioriot -% cd ioriot -% make -% sudo make install -% export PATH=$PATH:/opt/ioriot/bin -``` - -Note: It is not best practice to install any compilers on production systems. For further information please have a look at the enclosed README.md. - -### Recording of I/O events - -All I/O events are kernel related. If a process wants to perform an I/O operation, such as opening a file, it must inform the kernel of this by a system call (short syscall). I/O Riot relies on the Systemtap tool to record I/O syscalls. Systemtap, available for all popular Linux distributions, helps you to take a look at the running kernel in productive environments, which makes it predestined to monitor all I/O-relevant Linux syscalls and log them to a file. Other tools, such as strace, are not an alternative because they slow down the system too much. - -During recording, ioriot acts as a wrapper and executes all relevant Systemtap commands for you. Use the following command to log all events to io.capture: - -``` -% sudo ioriot -c io.capture -``` - -=> ./realistic-load-testing-with-ioriot-for-linux/figure1-ioriot-io-recording.png Screenshot I/O recording - -A Ctrl-C (SIGINT) stops recording prematurely. Otherwise, ioriot terminates itself automatically after 1 hour. Depending on the system load, the output file can grow to several gigabytes. Only metadata is logged, not the read and written data itself. When replaying later, only random data is used. Under certain circumstances, Systemtap may omit some system calls and issue warnings. This is to ensure that Systemtap does not consume too many resources. - -### Test preparation - -Then copy io.capture to a test system. The log also contains all accesses to the pseudo file systems devfs, sysfs and procfs. This makes little sense, which is why you must first generate a cleaned and playable version io.replay from io.capture as follows: - -``` -% sudo ioriot -c io.capture -r io.replay -u $USER -n TESTNAME -``` - -The parameter -n allows you to assign a freely selectable test name. An arbitrary system user under which the test is to be played is specified via paramater -u. - -### Test Initialization - -The test will most likely want to access existing files. These are files the test wants to read but does not create by itself. The existence of these must be ensured before the test. You can do this as follows: - -``` -% sudo ioriot -i io.replay -``` - -To avoid any damage to the running system, ioreplay only works in special directories. The tool creates a separate subdirectory for each file system mount point (e.g. /, /usr/local, /store/00,...) (here: /.ioriot/TESTNAME, /usr/local/.ioriot/TESTNAME, /store/00/.ioriot/TESTNAME,...). By default, the working directory of ioriot is /usr/local/ioriot/TESTNAME. - -=> ./realistic-load-testing-with-ioriot-for-linux/figure2-ioriot-test-preparation.png Screenshot test preparation - -You must re-initialize the environment before each run. Data from previous tests will be moved to a trash directory automatically, which can be finally deleted with "sudo ioriot -P". - -### Replay - -After initialization, you can replay the log with -r. You can use -R to initiate both test initialization and replay in a single command and -S can be used to specify a file in which statistics are written after the test run. - -You can also influence the playback speed: "-s 0" is interpreted as "Playback as fast as possible" and is the default setting. With "-s 1" all operations are performed at original speed. "-s 2" would double the playback speed and "-s 0.5" would halve it. - -=> ./realistic-load-testing-with-ioriot-for-linux/figure3-ioriot-replay.png Screenshot replaying I/O - -As an initial test, for example, you could compare the two Linux I/O schedulers CFQ and Deadline and check which scheduler the test runs the fastest. They run the test separately for each scheduler. The following shell loop iterates through all attached block devices of the system and changes their I/O scheduler to the one specified in variable $new_scheduler (in this case either cfq or deadline). Subsequently, all I/O events from the io.replay protocol are played back. At the end, an output file with statistics is generated: - -``` -% new_scheduler=cfq -% for scheduler in /sys/block/*/queue/scheduler; do - echo $new_scheduler | sudo tee $scheduler -done -% sudo ioriot -R io.replay -S cfq.txt -% new_scheduler=deadline -% for scheduler in /sys/block/*/queue/scheduler; do - echo $new_scheduler | sudo tee $scheduler -done -% sudo ioriot -R io.replay -S deadline.txt -``` - -According to the results, the test could run 940 seconds faster with Deadline Scheduler: - -``` -% cat cfq.txt -Num workers: 4 -hreads per worker: 128 -otal threads: 512 -Highest loadavg: 259.29 -Performed ioops: 218624596 -Average ioops/s: 101544.17 -Time ahead: 1452s -Total time: 2153.00s -% cat deadline.txt -Num workers: 4 -Threads per worker: 128 -Total threads: 512 -Highest loadavg: 342.45 -Performed ioops: 218624596 -Average ioops/s: 180234.62 -Time ahead: 2392s -Total time: 1213.00s -``` - -In any case, you should also set up a time series database, such as Graphite, where the I/O throughput can be plotted. Figures 4 and 5 show the read and write access times of both tests. The break-in makes it clear when the CFQ test ended and the deadline test was started. The reading latency of both tests is similar. Write latency is dramatically improved using the Deadline Scheduler. - -=> ./realistic-load-testing-with-ioriot-for-linux/figure4-ioriot-read-latency.png Graphite visualization of the mean read access times in ms with CFQ and Deadline Scheduler. - -=> ./realistic-load-testing-with-ioriot-for-linux/figure5-ioriot-write-latency.png Graphite visualization of the average write access times in ms with CFQ and Deadline Scheduler. - -You should also take a look at the iostat tool. The iostat screenshot shows the output of iostat -x 10 during a test run. As you can see, a block device is fully loaded with 99% utilization, while all other block devices still have sufficient buffer. This could be an indication of poor data distribution in the storage system and is worth pursuing. It is not uncommon for I/O Riot to reveal software problems. - -=> ./realistic-load-testing-with-ioriot-for-linux/figure6-iostat.png Output of iostat. The block device sdy seems to be almost fully utilized by 99%. - -## I/O Riot is Open Source - -The tool has already proven to be very useful and will continue to be actively developed as time and priority permits. Mimecast intends to be an ongoing contributor to Open Source. You can find I/O Riot at: - -=> https://github.com/mimecast/ioriot - -## Systemtap - -Systemtap is a tool for the instrumentation of the Linux kernel. The tool provides an AWK-like programming language. Programs written in it are compiled from Systemtap to C- and then into a dynamically loadable kernel module. Loaded into the kernel, the program has access to Linux internals. A Systemtap program written for I/O Riot monitors when, with which parameters, at which time, and from which process I/O syscalls take place and their return values. - -For example, the open syscall opens a file and returns the responsible file descriptor. The read and write syscalls can operate on a file descriptor and return the number of read or written bytes. The close syscall closes a given file descriptor. I/O Riot comes with a ready-made Systemtap program, which you have already compiled into a kernel module and installed to /opt/ioriot. In addition to open, read and close, it logs many other I/O-relevant calls. - -=> https://sourceware.org/systemtap/ - -## More refereces - -=> http://www.iozone.org/ IOZone -=> https://www.coker.com.au/bonnie++/ Bonnie++ -=> https://graphiteapp.org Graphite -=> https://en.wikipedia.org/wiki/Memory-mapped_I/O Memory mapped I/O - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2021-04-22-dtail-the-distributed-log-tail-program.gmi.tpl.f52534829ec99bc552b1c0323f75427f77265ee7cf35d302e9b655eb88267d6b b/gemfeed/.rcmbackup/2021-04-22-dtail-the-distributed-log-tail-program.gmi.tpl.f52534829ec99bc552b1c0323f75427f77265ee7cf35d302e9b655eb88267d6b deleted file mode 100644 index 79693808..00000000 --- a/gemfeed/.rcmbackup/2021-04-22-dtail-the-distributed-log-tail-program.gmi.tpl.f52534829ec99bc552b1c0323f75427f77265ee7cf35d302e9b655eb88267d6b +++ /dev/null @@ -1,114 +0,0 @@ -# DTail - The distributed log tail program - -> Published at 2021-04-22T19:28:41+01:00; Updated at 2021-04-26 - -This article first appeared at the Mimecast Engineering Blog but I made it available here in my personal internet site too. - -=> https://medium.com/mimecast-engineering/dtail-the-distributed-log-tail-program-79b8087904bb Original Mimecast Engineering Blog post at Medium - -Running a large cloud-based service requires monitoring the state of huge numbers of machines, a task for which many standard UNIX tools were not really designed. In this post, I will describe a simple program, DTail, that Mimecast has built and released as Open-Source, which enables us to monitor log files of many servers at once without the costly overhead of a full-blown log management system. - -At Mimecast, we run over 10 thousand server boxes. Most of them host multiple microservices and each of them produces log files. Even with the use of time series databases and monitoring systems, raw application logs are still an important source of information when it comes to analysing, debugging, and troubleshooting services. - -Every engineer familiar with UNIX or a UNIX-like platform (e.g., Linux) is well aware of tail, a command-line program for displaying a text file content on the terminal which is also especially useful for following application or system log files with tail -f logfile. - -Think of DTail as a distributed version of the tail program which is very useful when you have a distributed application running on many servers. DTail is an Open-Source, cross-platform, fairly easy to use, support and maintain log file analysis & statistics gathering tool designed for Engineers and Systems Administrators. It is programmed in Google Go. - -=> ./dtail-the-distributed-log-tail-program/title.png DTail logo image - -<< template::inline::toc - -## A Mimecast Pet Project - -DTail got its inspiration from public domain tools available already in this area but it is a blue sky from-scratch development which was first presented at Mimecast’s annual internal Pet Project competition (awarded with a Bronze prize). It has gained popularity since and is one of the most widely deployed DevOps tools at Mimecast (reaching nearly 10k server installations) and many engineers use it on a regular basis. The Open-Source version of DTail is available at: - -=> https://dtail.dev - -Try it out — We would love any feedback. But first, read on… - -## Differentiating from log management systems - -Why not just use a full-blown log management system? There are various Open-Source and commercial log management solutions available on the market you could choose from (e.g. the ELK stack). Most of them store the logs in a centralized location and are fairly complex to set up and operate. Possibly they are also pretty expensive to operate if you have to buy dedicated hardware (or pay fees to your cloud provider) and have to hire support staff for it. - -DTail does not aim to replace any of the log management tools already available but is rather an additional tool crafted especially for ad-hoc debugging and troubleshooting purposes. DTail is cheap to operate as it does not require any dedicated hardware for log storage as it operates directly on the source of the logs. It means that there is a DTail server installed on all server boxes producing logs. This decentralized comes with the direct advantages that there is no introduced delay because the logs are not shipped to a central log storage device. The reduced complexity also makes it more robust against outages. You won’t be able to troubleshoot your distributed application very well if the log management infrastructure isn’t working either. - -=> ./dtail-the-distributed-log-tail-program/dtail.gif DTail sample session animated gif - -As a downside, you won’t be able to access any logs with DTail when the server is down. Furthermore, a server can store logs only up to a certain capacity as disks will fill up. For the purpose of ad-hoc debugging, these are not typically issues. Usually, it’s the application you want to debug and not the server. And disk space is rarely an issue for bare metal and VM-based systems these days, with sufficient space for several weeks’ worth of log storage being available. DTail also supports reading compressed logs. The currently supported compression algorithms are gzip and zstd. - -## Combining simplicity, security and efficiency - -DTail also has a client component that connects to multiple servers concurrently for log files (or any other text files). - -The DTail client interacts with a DTail server on port TCP/2222 via SSH protocol and does not interact in any way with the system’s SSH server (e.g., OpenSSH Server) which might be running at port TCP/22 already. As a matter of fact, you don’t need a regular SSH server running for DTail at all. There is no support for interactive login shells at TCP/2222 either, as by design that port can only be used for text data streaming. The SSH protocol is used for the public/private key infrastructure and transport encryption only and DTail implements its own protocol on top of SSH for the features provided. There is no need to set up or buy any additional TLS certificates. The port 2222 can be easily reconfigured if you preferred to use a different one. - -The DTail server, which is a single static binary, will not fork an external process. This means that all features are implemented in native Go code (exception: Linux ACL support is implemented in C, but it must be enabled explicitly on compile time) and therefore helping to make it robust, secure, efficient, and easy to deploy. A single client, running on a standard Laptop, can connect to thousands of servers concurrently while still maintaining a small resource footprint. - -Recent log files are very likely still in the file system caches on the servers. Therefore, there tends to be a minimal I/O overhead involved. - -## The DTail family of commands - -Following the UNIX philosophy, DTail includes multiple command-line commands each of them for a different purpose: - -* dserver: The DTail server, the only binary required to be installed on the servers involved. -* dtail: The distributed log tail client for following log files. -* dcat: The distributed cat client for concatenating and displaying text files. -* dgrep: The distributed grep client for searching text files for a regular expression pattern. -* dmap: The distributed map-reduce client for aggregating stats from log files. - -=> ./dtail-the-distributed-log-tail-program/dgrep.gif DGrep sample session animated gif - -## Usage example - -The use of these commands is almost self-explanatory for a person already used to the standard command line in Unix systems. One of the main goals is to make DTail easy to use. A tool that is too complicated to use under high-pressure scenarios (e.g., during an incident) can be quite detrimental. - -The basic idea is to start one of the clients from the command line and provide a list of servers to connect to with –servers. You also must provide a path of remote (log) files via –files. If you want to process multiple files per server, you could either provide a comma-separated list of file paths or make use of file system globbing (or a combination of both). - -The following example would connect to all DTail servers listed in the serverlist.txt, follow all files with the ending .log and filter for lines containing the string error. You can specify any Go compatible regular expression. In this example we add the case-insensitive flag to the regex: - -``` -dtail –servers serverlist.txt –files ‘/var/log/*.log’ –regex ‘(?i:error)’ -``` - -You usually want to specify a regular expression as a client argument. This will mean that responses are pre-filtered for all matching lines on the server-side and thus sending back only the relevant lines to the client. If your logs are growing very rapidly and the regex is not specific enough there might be the chance that your client is not fast enough to keep up processing all of the responses. This could be due to a network bottleneck or just as simple as a slow terminal emulator displaying the log lines on the client-side. - -A green 100 in the client output before each log line received from the server always indicates that there were no such problems and 100% of all log lines could be displayed on your terminal (have a look at the animated Gifs in this post). If the percentage falls below 100 it means that some of the channels used by the servers to send data to the client are congested and lines were dropped. In this case, the color will change from green to red. The user then could decide to run the same query but with a more specific regex. - -You could also provide a comma-separated list of servers as opposed to a text file. There are many more options you could use. The ones listed here are just the very basic ones. There are more instructions and usage examples on the GitHub page. Also, you can study even more of the available options via the –help switch (some real treasures might be hidden there). - -## Fitting it in - -DTail integrates nicely into the user management of existing infrastructure. It follows normal system permissions and does not open new “holes” on the server which helps to keep security departments happy. The user would not have more or less file read permissions than he would have via a regular SSH login shell. There is a full SSH key, traditional UNIX permissions, and Linux ACL support. There is also a very low resource footprint involved. On average for tailing and searching log files less than 100MB RAM and less than a quarter of a CPU core per participating server are required. Complex map-reduce queries on big data sets will require more resources accordingly. - -## Advanced features - -The features listed here are out of the scope of this blog post but are worthwhile to mention: - -* Distributed map-reduce queries on stats provided in log files with dmap. dmap comes with its own SQL-like aggregation query language. -* Stats streaming with continuous map-reduce queries. The difference to normal queries is that the stats are aggregated over a specified interval only on the newly written log lines. Thus, giving a de-facto live stat view for each interval. -* Server-side scheduled queries on log files. The queries are configured in the DTail server configuration file and scheduled at certain time intervals. Results are written to CSV files. This is useful for generating daily stats from the log files without the need for an interactive client. -* Server-side stats streaming with continuous map-reduce queries. This for example can be used to periodically generate stats from the logs at a configured interval, e.g., log error counts by the minute. These then can be sent to a time-series database (e.g., Graphite) and then plotted in a Grafana dashboard. -* Support for custom extensions. E.g., for different server discovery methods (so you don’t have to rely on plain server lists) and log file formats (so that map-reduce queries can parse more stats from the logs). - -## For the future - -There are various features we want to see in the future. - -* A spartan mode, not printing out any extra information but the raw remote log files would be a nice feature to have. This will make it easier to post-process the data produced by the DTail client with common UNIX tools. (To some degree this is possible already, just disable the ANSI terminal color output of the client with -noColors and pipe the output to another program). -* Tempting would be implementing the dgoawk command, a distributed version of the AWK programming language purely implemented in Go, for advanced text data stream processing capabilities. There are 3rd party libraries available implementing AWK in pure Go which could be used. -* A more complex change would be the support of federated queries. You can connect to thousands of servers from a single client running on a laptop. But does it scale to 100k of servers? Some of the servers could be used as middleware for connecting to even more servers. -* Another aspect is to extend the documentation. Especially the advanced features such as map-reduce query language and how to configure the server-side queries currently do require more documentation. For now, you can read the code, sample config files or just ask the author for that! But this will be certainly addressed in the future. - -## Open Source - -Mimecast highly encourages you to have a look at DTail and submit an issue for any features you would like to see. Have you found a bug? Maybe you just have a question or comment? If you want to go a step further: We would also love to see pull requests for any features or improvements. Either way, if in doubt just contact us via the DTail GitHub page. - -=> https://dtail.dev - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -Other related posts are: - -<< template::inline::rindex dtail - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2021-04-24-welcome-to-the-geminispace.gmi.tpl.13614cbbfbbb35af77d09d0610f3a8b9ff63c8852afd8cca146767b119895f9a b/gemfeed/.rcmbackup/2021-04-24-welcome-to-the-geminispace.gmi.tpl.13614cbbfbbb35af77d09d0610f3a8b9ff63c8852afd8cca146767b119895f9a deleted file mode 100644 index 1a65cd3e..00000000 --- a/gemfeed/.rcmbackup/2021-04-24-welcome-to-the-geminispace.gmi.tpl.13614cbbfbbb35af77d09d0610f3a8b9ff63c8852afd8cca146767b119895f9a +++ /dev/null @@ -1,89 +0,0 @@ -# Welcome to the Geminispace - -> Published at 2021-04-24T19:28:41+01:00; Updated at 2021-06-18 - -``` - - /\ - / \ - | | - |NASA| - | | - | | - | | - ' ` - |Gemini| - | | - |______| - '-`'-` . - / . \'\ . .' - ''( .'\.' ' .;' -'.;.;' ;'.;' ..;;' AsH - -``` - -<< template::inline::toc - -## Introduction - -Have you reached this article already via Gemini? It requires a Gemini client; web browsers such as Firefox, Chrome, Safari, etc., don't support the Gemini protocol. The Gemini address of this site (or the address of this capsule as people say in Geminispace) is: - -=> gemini://foo.zone - -However, if you still use HTTP, you are just surfing the fallback HTML version of this capsule. In that case, I suggest reading on what this is all about :-). - -## Motivation - -### My urge to revamp my personal website - -For some time, I had to urge to revamp my personal website. Not to update the technology and its design but to update all the content (+ keep it current) and start a small tech blog again. So unconsciously, I began to search for an excellent platform to do all of that in a KISS (keep it simple & stupid) way. - -### My still great Laptop running hot - -Earlier this year (2021), I noticed that my almost seven-year-old but still great Laptop started to become hot and slowed down while surfing the web. Also, the Laptop's fan became quite noisy. This was all due to the additional bloat such as JavaScript, excessive use of CSS, tracking cookies+pixels, ads, and so on there was on the website. - -All I wanted was to read an interesting article, but after a big advertising pop-up banner appeared and made everything worse, I gave up and closed the browser tab. - -## Discovering the Gemini internet protocol - -Around the same time, I discovered a relatively new, more lightweight protocol named Gemini, which does not support all these CPU-intensive features like HTML, JavaScript, and CSS. Also, tracking and ads are unsupported by the Gemini protocol. - -The "downside" is that due to the limited capabilities of the Gemini protocol, all sites look very old and spartan. But that is not a downside; that is, in fact, a design choice people made. It is up to the client software how your capsule looks. For example, you could use a graphical client, such as Lagrange, with nice font renderings and colours to improve the appearance. Or you could use a very minimalistic command line black-and-white Gemini client. It's your (the user's) choice. - -=> ./welcome-to-the-geminispace/amfora-screenshot.png Screenshot Amfora Gemini terminal client surfing this site -=> ./welcome-to-the-geminispace/lagrange-screenshot.png Screenshot graphical Lagrange Gemini client surfing this site - -Why is there a need for a new protocol? As the modern web is a superset of Gemini, can't we use simple HTML 1.0 instead? That's a good and valid question. It is not a technical problem but a human problem. We tend to abuse the features once they are available. You can ensure that things stay efficient and straightforward as long as you are using the Gemini protocol. On the other hand, you can't force every website on the modern web to only create plain and straightforward-looking HTML pages. - -## My own Gemini capsule - -As it is effortless to set up and maintain your own Gemini capsule (Gemini server + content composed via the Gemtext markup language), I decided to create my own. What I like about Gemini is that I can use my favourite text editor and get typing. I don't need to worry about the style and design of the presence, and I also don't have to test anything in ten different web browsers. I can only focus on the content! As a matter of fact, I am using the Vim editor + its spellchecker + auto word completion functionality to write this. - -This site was generated with Gemtexter. You can read more about it here: - -=> ./2021-06-05-gemtexter-one-bash-script-to-rule-it-all.gmi Gemtexter - One Bash script to rule it all - -## Gemini advantages summarised - -* Supports an alternative to the modern bloated web -* Easy to operate and easy to write content -* No need to worry about various web browser compatibilities -* It's the client's responsibility how the content is designed+presented -* Lightweight (although not as lightweight as the Gopher protocol) -* Supports privacy (no cookies, no request header fingerprinting, TLS encryption) -* Fun to play with (it's a bit geeky, yes, but a lot of fun!) - -## Dive into deep Gemini space - -Check out one of the following links for more information about Gemini. For example, you will find a FAQ that explains why the protocol is named Gemini. Many Gemini capsules are dual-hosted via Gemini and HTTP(S) so that people new to Gemini can sneak peek at the content with a regular web browser. Some people go as far as tri-hosting all their content via HTTP(S), Gemini and Gopher. - -=> gemini://geminiprotocol.net/ -=> https://geminiprotocol.net/ - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -Other related posts are: - -<< template::inline::rindex gemtext gemini - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2021-05-16-personal-bash-coding-style-guide.gmi.tpl.d38b7b180488f50c00ec16c4e13131db3954e915a6c7259bf1eb7f8f15d2297e b/gemfeed/.rcmbackup/2021-05-16-personal-bash-coding-style-guide.gmi.tpl.d38b7b180488f50c00ec16c4e13131db3954e915a6c7259bf1eb7f8f15d2297e deleted file mode 100644 index 9c67046c..00000000 --- a/gemfeed/.rcmbackup/2021-05-16-personal-bash-coding-style-guide.gmi.tpl.d38b7b180488f50c00ec16c4e13131db3954e915a6c7259bf1eb7f8f15d2297e +++ /dev/null @@ -1,395 +0,0 @@ -# Personal Bash coding style guide - -> Published at 2021-05-16T14:51:57+01:00 - -Lately, I have been polishing and writing a lot of Bash code. Not that I never wrote a lot of Bash, but now as I also looked through the Google Shell Style Guide, I thought it is time also to write my thoughts on that. I agree with that guide in most, but not in all points. - -=> https://google.github.io/styleguide/shellguide.html Google Shell Style Guide - -``` - .---------------------------. - /,--..---..---..---..---..--. `. - //___||___||___||___||___||___\_| - [j__ ######################## [_| - \============================| - .==| |"""||"""||"""||"""| |"""|| -/======"---""---""---""---"=| =|| -|____ []* ____ | ==|| -// \\ // \\ |===|| hjw -"\__/"---------------"\__/"-+---+' -``` - -<< template::inline::toc - -## My modifications - -These are my modifications to the Google Guide. - -### Shebang - -Google recommends using always... - -```bash -#!/bin/bash -``` - -... as the shebang line, but that does not work on all Unix and Unix-like operating systems (e.g., the *BSDs don't have Bash installed to /bin/bash). Better is: - -```bash -#!/usr/bin/env bash -``` - -### Two space soft-tabs indentation - -I know there have been many tab- and soft-tab wars on this planet. Google recommends using two space soft-tabs for Bash scripts. - -I don't care if I use two or four space indentations. I agree, however, that we should not use tabs. I tend to use four-space soft-tabs as that's how I currently configured Vim for any programming language. What matters most, though, is consistency within the same script/project. - -Google also recommends limiting the line length to 80 characters. For some people, that seems to be an old habit from the '80s, where all computer terminals couldn't display longer lines. But I think that the 80 character mark is still a good practice, at least for shell scripts. For example, I am often writing code on a Microsoft Go Tablet PC (running Linux, of course), and it comes in convenient if the lines are not too long due to the relatively small display on the device. - -I hit the 80 character line length quicker with the four spaces than with two spaces, but that makes me refactor the Bash code more aggressively, which is a good thing. - -### Breaking long pipes - -Google recommends breaking up long pipes like this: - -```bash -# All fits on one line -command1 | command2 - -# Long commands -command1 \ - | command2 \ - | command3 \ - | command4 -``` - -I think there is a better way like the following, which is less noisy. The pipe | already indicates the Bash that another command is expected, thus making the explicit line breaks with \ obsolete: - -```bash -# Long commands -command1 | - command2 | - command3 | - command4 -``` - -> Update: It's 2023 now, and I have changed my mind. I think Google's way is the better one. It may be a bit more to type, but the leading `|` are a nice eye catcher, so you know immediately what is going on! - -### Quoting your variables - -Google recommends always quote your variables. Generally, it would be best if you did that only for variables where you are unsure about the content/values of the variables (e.g., content is from an external input source and may contain whitespace or other special characters). In my opinion, the code will become quite noisy when you always quote your variables like this: - -```bash -greet () { - local -r greeting="${1}" - local -r name="${2}" - echo "${greeting} ${name}!" -} -``` - -In this particular example, I agree that you should quote them as you don't know the input (are there, for example, whitespace characters?). But if you are sure that you are only using simple bare words, then I think that the code looks much cleaner when you do this instead: - -```bash -say_hello_to_paul () { - local -r greeting=Hello - local -r name=Paul - echo "$greeting $name!" -} -``` - -You see, I also omitted the curly braces { } around the variables. I only use the curly braces around variables when it makes the code either easier/clearer to read or if it is necessary to use them: - -```bash -declare FOO=bar -# Curly braces around FOO are necessary -echo "foo${FOO}baz" -``` - -A few more words on always quoting the variables: For the sake of consistency (and for making ShellCheck happy), I am not against quoting everything I encounter. I also think that the larger the Bash script becomes, the more critical it becomes always to quote variables. That's because it will be more likely that you might not remember that some of the functions don't work on values with spaces in them, for example. It's just that I won't quote everything in every small script I write. - -### Prefer built-in commands over external commands - -Google recommends using the built-in commands over available external commands where possible: - -```bash -# Prefer this: -addition=$(( X + Y )) -substitution="${string/#foo/bar}" - -# Instead of this: -addition="$(expr "${X}" + "${Y}")" -substitution="$(echo "${string}" | sed -e 's/^foo/bar/')" -``` - -I can't entirely agree here. The external commands (especially sed) are much more sophisticated and powerful than the built-in Bash versions. Sed can do much more than the Bash can ever do by itself when it comes to text manipulation (the name "sed" stands for streaming editor, after all). - -I prefer to do light text processing with the Bash built-ins and more complicated text processing with external programs such as sed, grep, awk, cut, and tr. However, there is also medium-light text processing where I would want to use external programs. That is so because I remember using them better than the Bash built-ins. The Bash can get relatively obscure here (even Perl will be more readable then - Side note: I love Perl). - -Also, you would like to use an external command for floating-point calculation (e.g., bc) instead of using the Bash built-ins (worth noticing that ZSH supports built-in floating-points). - -I even didn't get started with what you can do with awk (especially GNU Awk), a fully-fledged programming language. Tiny Awk snippets tend to be used quite often in Shell scripts without honouring the real power of Awk. But if you did everything in Perl or Awk or another scripting language, then it wouldn't be a Bash script anymore, wouldn't it? ;-) - -## My additions - -### Use of 'yes' and 'no' - -Bash does not support a boolean type. I tend just to use the strings 'yes' and 'no' here. I used 0 for false and 1 for true for some time, but I think that the yes/no strings are easier to read. Yes, the Bash script would need to perform string comparisons on every check, but if performance is crucial to you, you wouldn't want to use a Bash script anyway, correct? - -```bash -declare -r SUGAR_FREE=yes -declare -r I_NEED_THE_BUZZ=no - -buy_soda () { - local -r sugar_free=$1 - - if [[ $sugar_free == yes ]]; then - echo 'Diet Dr. Pepper' - else - echo 'Pepsi Coke' - fi -} - -buy_soda $I_NEED_THE_BUZZ -``` - -### Non-evil alternative to variable assignments via eval - -Google is in the opinion that eval should be avoided. I think so too. They list these examples in their guide: - -```bash -# What does this set? -# Did it succeed? In part or whole? -eval $(set_my_variables) - -# What happens if one of the returned values has a space in it? -variable="$(eval some_function)" -``` - -However, if I want to read variables from another file, I don't have to use eval here. I only have to source the file: - -``` -% cat vars.source.sh -declare foo=bar -declare bar=baz -declare bay=foo - -% bash -c 'source vars.source.sh; echo $foo $bar $baz' -bar baz foo -``` - -And suppose I want to assign variables dynamically. In that case, I could just run an external script and source its output (This is how you could do metaprogramming in Bash without the use of eval - write code which produces code for immediate execution): - -``` -% cat vars.sh -#!/usr/bin/env bash -cat <<END -declare date="$(date)" -declare user=$USER -END - -% bash -c 'source <(./vars.sh); echo "Hello $user, it is $date"' -Hello paul, it is Sat 15 May 19:21:12 BST 2021 -``` - -The downside is that ShellCheck won't be able to follow the dynamic sourcing anymore. - -### Prefer pipes over arrays for list processing - -When I do list processing in Bash, I prefer to use pipes. You can chain them through Bash functions as well, which is pretty neat. Usually, my list processing scripts are of a structure like this: - -```bash -filter_lines () { - echo 'Start filtering lines in a fancy way!' >&2 - grep ... | sed .... -} - -process_lines () { - echo 'Start processing line by line!' >&2 - while read -r line; do - ... do something and produce a result... - echo "$result" - done -} - -# Do some post-processing of the data -postprocess_lines () { - echo 'Start removing duplicates!' >&2 - sort -u -} - -genreate_report () { - echo 'My boss wants to have a report!' >&2 - tee outfile.txt - wc -l outfile.txt -} - -main () { - filter_lines | - process_lines | - postprocess_lines | - generate_report -} - -main -``` - -The stdout is always passed as a pipe to the next following stage. The stderr is used for info logging. - -### Assign-then-shift - -I often refactor existing Bash code. That leads me to add and removing function arguments quite often. It's pretty repetitive work changing the $1, $2.... function argument numbers every time you change the order or add/remove possible arguments. - -The solution is to use of the "assign-then-shift"-method, which goes like this: "local -r var1=$1; shift; local -r var2=$1; shift". The idea is that you only use "$1" to assign function arguments to named (better readable) local function variables. You will never have to bother about "$2" or above. That is very useful when you constantly refactor your code and remove or add function arguments. It's something that I picked up from a colleague (a pure Bash wizard) some time ago: - -```bash -some_function () { - local -r param_foo="$1"; shift - local -r param_baz="$1"; shift - local -r param_bay="$1"; shift - - # ... -} -``` - -Want to add a param_baz? Just do this: - -```bash -some_function () { - local -r param_foo="$1"; shift - local -r param_bar="$1"; shift - local -r param_baz="$1"; shift - local -r param_bay="$1"; shift - - # ... -} -``` - -Want to remove param_foo? Nothing easier than that: - -```bash -some_function () { - local -r param_bar="$1"; shift - local -r param_baz="$1"; shift - local -r param_bay="$1"; shift - - # ... -} -``` - -As you can see, I didn't need to change any other assignments within the function. Of course, you would also need to change the function argument lists at every occasion where the function is invoked - you would do that within the same refactoring session. - -### Paranoid mode - -I call this the paranoid mode. The Bash will stop executing when a command exits with a status not equal to 0: - -```bash -set -e -grep -q foo <<< bar -echo Jo -``` - -Here 'Jo' will never be printed out as the grep didn't find any match. It's unrealistic for most scripts to run in paranoid mode purely, so there must be a way to add exceptions. Critical Bash scripts of mine tend to look like this: - -```bash -#!/usr/bin/env bash - -set -e - -some_function () { - # .. some critical code - # ... - - set +e - # Grep might fail, but that's OK now - grep .... - local -i ec=$? - set -e - - # .. critical code continues ... - if [[ $ec -ne 0 ]]; then - : # ... - fi - # ... -} -``` - -## Learned - -There are also a couple of things I've learned from Google's guide. - -### Unintended lexicographical comparison. - -The following looks like a valid Bash code: - -```bash -if [[ "${my_var}" > 3 ]]; then - # True for 4, false for 22. - do_something -fi -``` - -... but it is probably an unintended lexicographical comparison. A correct way would be: - -```bash -if (( my_var > 3 )); then - do_something -fi -``` - -or - -```bash -if [[ "${my_var}" -gt 3 ]]; then - do_something -fi -``` - -### PIPESTATUS - -I have never used the PIPESTATUS variable before. I knew that it's there, but I never bothered to understand how it works until now thoroughly. - -The PIPESTATUS variable in Bash allows checking of the return code from all parts of a pipe. If it's only necessary to check the success or failure of the whole pipe, then the following is acceptable: - -```bash -tar -cf - ./* | ( cd "${dir}" && tar -xf - ) -if (( PIPESTATUS[0] != 0 || PIPESTATUS[1] != 0 )); then - echo "Unable to tar files to ${dir}" >&2 -fi -``` - -However, as PIPESTATUS will be overwritten as soon as you do any other command, if you need to act differently on errors based on where it happened in the pipe, you'll need to assign PIPESTATUS to another variable immediately after running the command (don't forget that [ is a command and will wipe out PIPESTATUS). - -```bash -tar -cf - ./* | ( cd "${DIR}" && tar -xf - ) -return_codes=( "${PIPESTATUS[@]}" ) -if (( return_codes[0] != 0 )); then - do_something -fi -if (( return_codes[1] != 0 )); then - do_something_else -fi -``` - -## Use common sense and BE CONSISTENT. - -The following two paragraphs are thoroughly quoted from the Google guidelines. But they hit the hammer on the head: - -> If you are editing code, take a few minutes to look at the code around you and determine its style. If they use spaces around their if clauses, you should, too. If their comments have little boxes of stars around them, make your comments have little boxes of stars around them too. - -> The point of having style guidelines is to have a common vocabulary of coding so people can concentrate on what you are saying rather than on how you are saying it. We present global style rules here, so people know the vocabulary. But local style is also important. If the code you add to a file looks drastically different from the existing code around it, the discontinuity throws readers out of their rhythm when they go to read it. Try to avoid this. - - -## Advanced Bash learning pro tip - -I also highly recommend having a read through the "Advanced Bash-Scripting Guide" (not from Google). I use it as the universal Bash reference and learn something new every time I look at it. - -=> https://tldp.org/LDP/abs/html/ Advanced Bash-Scripting Guide - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -Other related posts are: - -<< template::inline::rindex bash - -=> ../ Back to the main site diff --git a/gemfeed/.rcmbackup/2021-06-05-gemtexter-one-bash-script-to-rule-it-all.gmi.tpl.48552bc263f579a1f98651ed83fd6328ef19314610df8b3e6347725a2951143e b/gemfeed/.rcmbackup/2021-06-05-gemtexter-one-bash-script-to-rule-it-all.gmi.tpl.48552bc263f579a1f98651ed83fd6328ef19314610df8b3e6347725a2951143e deleted file mode 100644 index 883e130a..00000000 --- a/gemfeed/.rcmbackup/2021-06-05-gemtexter-one-bash-script-to-rule-it-all.gmi.tpl.48552bc263f579a1f98651ed83fd6328ef19314610df8b3e6347725a2951143e +++ /dev/null @@ -1,174 +0,0 @@ -# Gemtexter - One Bash script to rule it all - -> Published at 2021-06-05T19:03:32+01:00 - -You might have read my previous blog posts about entering the Geminispace, where I pointed out the benefits of having and maintaining an internet presence there. This whole site (the blog and all other pages) is composed in the Gemtext markup language. - -This comes with the benefit that I can write content in my favourite text editor (Vim). - -``` - o .,<>., o - |\/\/\/\/| - '========' - (_ SSSSSSs - )a'`SSSSSs - /_ SSSSSS - .=## SSSSS - .#### SSSSs - ###::::SSSSS - .;:::""""SSS - .:;:' . . \\ - .::/ ' .'| - .::( . | - :::) \ - /\( / - /) ( | - .' \ . ./ / - _-' |\ . | - _..--.. . /"---\ | ` | . | - -=====================,' _ \=(*#(7.#####() | `/_.. , ( - _.-''``';'-''-) ,. \ ' '+/// | .'/ \ ``-.) \ - ,' _.- (( `-' `._\ `` \_/_.' ) /`-._ ) | - ,'\ ,' _.'.`:-. \.-' / <_L )" | - _/ `._,' ,')`; `-'`' | L / / - / `. ,' ,|_/ / \ ( <_-' \ - \ / `./ ' / /,' \ /|` `. | - )\ /`._ ,'`._.-\ |) \' - / `.' )-'.-,' )__) |\ `| - : /`. `.._(--.`':`':/ \ ) \ \ - |::::\ ,'/::;-)) / ( )`. | - ||::::: . .::': :`-( |/ . | - ||::::| . :| |==[]=: . - \ - |||:::| : || : | | /\ ` | - ___ ___ '|;:::| | |' \=[]=| / \ \ -| /_ ||``|||::::: | ; | | | \_.'\_ `-. -: \_``[]--[]|::::'\_;' )-'..`._ .-'\``:: ` . \ - \___.>`''-.||:.__,' SSt |_______`> <_____:::. . . \ _/ - `+a:f:......jrei''' -``` - -<< template::inline::toc - -## Motivation - -Another benefit of using Gemini is that the Gemtext markup language is easy to parse. As my site is dual-hosted (Gemini+HTTP), I could, in theory, just write a shell script to deal with the conversion from Gemtext to HTML; there is no need for a full-featured programming language here. I have done a lot of Bash in the past, but I am also often revisiting old tools and techniques for refreshing and keeping the knowledge up to date here. - -=> ./gemtexter-one-bash-script-to-rule-it-all/blog-engine.jpg Motivational comic strip - -I have exactly done that - I wrote a Bash script, named Gemtexter, for that: - -=> https://codeberg.org/snonux/gemtexter - -In short, Gemtexter is a static site generator and blogging engine that uses Gemtext as its input format. - -## Output formats - -Gemtexter takes the Gemtext Markup files as the input and generates the following outputs from it (you find examples for each of these output formats on the Gemtexter GitHub page): - -* HTML files for my website -* Markdown files for a GitHub page -* A Gemtext Atom feed for my blog posts -* A Gemfeed for my blog posts (a particular feed format commonly used in Geminispace. The Gemfeed can be used as an alternative to the Atom feed). -* An HTML Atom feed of my blog posts - -I could have done all of that with a more robust language than Bash (such as Perl, Ruby, Go...), but I didn't. The purpose of this exercise was to challenge what I can do with a "simple" Bash script and learn new things. - -## Taking it as far as I should, but no farther - -The Bash is suitable very well for small scripts and ad-hoc automation on the command line. But it is for sure not a robust programming language. Writing this blog post, Gemtexter is nearing 1000 lines of code, which is actually a pretty large Bash script. - -### Modularization - -I modularized the code so that each core functionality has its own file in ./lib. All the modules are included from the main Gemtexter script. For example, there is one module for HTML generation, one for Markdown generation, and so on. - -```sh -paul in uranus in gemtexter on 🌱 main -❯ wc -l gemtexter lib/* - 117 gemtexter - 59 lib/assert.source.sh - 128 lib/atomfeed.source.sh - 64 lib/gemfeed.source.sh - 161 lib/generate.source.sh - 50 lib/git.source.sh - 162 lib/html.source.sh - 30 lib/log.source.sh - 63 lib/md.source.sh - 834 total -``` - -This way, the script could grow far beyond 1000 lines of code and still be maintainable. With more features, execution speed may slowly become a problem, though. I already notice that Gemtexter doesn't produce results instantly but requires few seconds of runtime already. That's not a problem yet, though. - -### Bash best practises and ShellCheck - -While working on Gemtexter, I also had a look at the Google Shell Style Guide and wrote a blog post on that: - -=> ./2021-05-16-personal-bash-coding-style-guide.gmi Personal bash coding style guide - -I followed all these best practices, and in my opinion, the result is a pretty maintainable Bash script (given that you are fluent with all the sed and grep commands I used). - -ShellCheck, a shell script analysis tool written in Haskell, is run on Gemtexter ensuring that all code is acceptable. I am pretty impressed with what ShellCheck found. - -It, for example, detected "some_command | while read var; do ...; done" loops and hinted that these create a new subprocess for the while part. The result is that all variable modifications taking place in the while-subprocess won't reflect the primary Bash process. ShellSheck then recommended rewriting the loop so that no subprocess is spawned as "while read -r var; do ...; done < <(some_command)". ShellCheck also pointed out to add a "-r" to "read"; otherwise, there could be an issue with backspaces in the loop data. - -Furthermore, ShellCheck recommended many more improvements. Declaration of unused variables and missing variable and string quotations were the most common ones. ShellSheck immensely helped to improve the robustness of the script. - -=> https://shellcheck.net - -### Unit testing - -There is a basic unit test module in ./lib/assert.source.sh, which is used for unit testing. I found this to be very beneficial for cross-platform development. For example, I noticed that some unit tests failed on macOS while everything still worked fine on my Fedora Linux laptop. - -After digging a bit, I noticed that I had to install the GNU versions of the sed and grep commands on macOS and a newer version of the Bash to make all unit tests pass and Gemtexter work. - -It has been proven quite helpful to have unit tests in place for the HTML part already when working on the Markdown generator part. To test the Markdown part, I copied the HTML unit tests and changed the expected outcome in the assertions. This way, I could implement the Markdown generator in a test-driven way (writing the test first and afterwards the implementation). - -### HTML unit test example - -```bash -gemtext='=> http://example.org Description of the link' -assert::equals "$(generate::make_link html "$gemtext")" \ - '<a class="textlink" href="http://example.org">Description of the link</a><br />' -``` - -### Markdown unit test example - -```bash -gemtext='=> http://example.org Description of the link' -assert::equals "$(generate::make_link md "$gemtext")" \ - '[Description of the link](http://example.org) ' -``` - -## Handcrafted HTML styles - -I had a look at some ready off the shelf CSS styles, but they all seemed too bloated. There is a whole industry selling CSS styles on the interweb. I preferred an effortless and minimalist style for the HTML site. So I handcrafted the Cascading Style Sheets manually with love and included them in the HTML header template. - -For now, I have to re-generate all HTML files whenever the CSS changes. That should not be an issue now, but I might move the CSS into a separate file one day. - -It's worth mentioning that all generated HTML files and Atom feeds pass the W3C validation tests. - -## Configurability - -In case someone else than me wants to use Gemtexter for his own site, it is pretty much configurable. It is possible to specify your own configuration file and your own HTML templates. Have a look at the GitHub page for examples. - -## Future features - -I could think of the following features added to a future version of Gemtexter: - -* Templating of Gemtext files so that the .gmi files are generated from .gmi.tpl files. The template engine could do such things as an automatic table of contents and sitemap generation. It could also include the output of inlined shell code, e.g. a fortune quote. -* Add support for more output formats, such as Groff, PDF, plain text, Gopher, etc. -* External CSS file for HTML. -* Improve speed by introducing parallelism and/or concurrency and/or better caching. - -## Conclusion - -It was quite a lot of fun writing Gemtexter. It's a relatively small project, but given that I worked on that in my spare time once in a while, it kept me busy for several weeks. - -I finally revamped my personal internet site and started to blog again. I wanted the result to be exactly how it is now: A slightly retro-inspired internet site built for fun with unconventional tools. - -E-Mail your comments to `paul@nospam.buetow.org` :-) - -Other related posts are: - -<< template::inline::rindex gemtext gemini bash - -=> ../ Back to the main site |