feat: Add randomSpread and RunInterval to checks

This commit introduces two new optional parameters to the check configuration:

- `randomSpread`: This parameter allows specifying a random sleep time up to N seconds before a check is executed. This is useful to avoid all checks running at the same time.
- `RunInterval`: This parameter defines the minimum interval in seconds between two executions of a check. This is useful if gogios is run more frequently than a specific check should be.

The `README.md` has been updated to document these new features.

fix: Fix deadlock when skipping checks

This commit also fixes a deadlock that occurred when a check was skipped due to the `RunInterval` setting. The `inputWg.Done()` was not being called, causing the main goroutine to wait forever.

build: Replace Taskfile with Magefile

The `Taskfile.yml` has been replaced with a `Magefile.go` to manage the build process. This provides more flexibility and is more idiomatic for Go projects.

7 files changed, 188 insertions, 16 deletions

diff --git a/.gitignore b/.gitignore
index 849ddff..0cd806a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
-dist/
+gogios
+dist/
\ No newline at end of file
diff --git a/Magefile.go b/Magefile.go
new file mode 100644
index 0000000..dc7d90b
--- /dev/null
+++ b/Magefile.go
@@ -0,0 +1,105 @@
+//go:build mage
+// +build mage
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+
+	"github.com/magefile/mage/mg"
+)
+
+// Build builds the gogios binary.
+func Build() error {
+	fmt.Println("Building...")
+	cmd := exec.Command("go", "build", "-o", "gogios", "cmd/gogios/main.go")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+// Dev builds the gogios binary with race detection.
+func Dev() error {
+	mg.Deps(Vet, Lint)
+	fmt.Println("Building with race detector...")
+	cmd := exec.Command("go", "build", "-race", "-o", "gogios", "cmd/gogios/main.go")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+// Vet runs go vet on all go files.
+func Vet() error {
+	fmt.Println("Vetting...")
+	cmd := exec.Command("go", "vet", "./...")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+// Lint runs golangci-lint.
+func Lint() error {
+	fmt.Println("Linting...")
+	cmd := exec.Command("golangci-lint", "run")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+// LintInstall installs golangci-lint.
+func LintInstall() error {
+	fmt.Println("Installing golangci-lint...")
+	cmd := exec.Command("go", "install", "github.com/golangci/golangci-lint/cmd/golangci-lint@latest")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+// Test runs all unit tests.
+func Test() error {
+	fmt.Println("Cleaning test cache...")
+	cleanCmd := exec.Command("go", "clean", "-testcache")
+	cleanCmd.Stdout = os.Stdout
+	cleanCmd.Stderr = os.Stderr
+	if err := cleanCmd.Run(); err != nil {
+		return err
+	}
+
+	fmt.Println("Running tests...")
+	testCmd := exec.Command("go", "test", "./...")
+	testCmd.Stdout = os.Stdout
+	testCmd.Stderr = os.Stderr
+	return testCmd.Run()
+}
+
+// Openbsd builds and deploys the gogios binary for OpenBSD.
+func Openbsd() error {
+	mg.Deps(BuildOpenbsd, DeployOpenbsd)
+	return nil
+}
+
+// BuildOpenbsd builds the gogios binary for OpenBSD.
+func BuildOpenbsd() error {
+	fmt.Println("Building for OpenBSD...")
+	if err := os.Setenv("GOOS", "openbsd"); err != nil {
+		return err
+	}
+	if err := os.Setenv("GOARCH", "amd64"); err != nil {
+		return err
+	}
+	cmd := exec.Command("go", "build", "-o", "gogios", "cmd/gogios/main.go")
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	return cmd.Run()
+}
+
+// DeployOpenbsd copies the gogios binary for OpenBSD.
+func DeployOpenbsd() error {
+	fmt.Println("Copying binary...")
+	cpCmd := exec.Command("cp", "gogios", "/home/paul/git/conf/frontends/usr/local/bin/gogios")
+	cpCmd.Stdout = os.Stdout
+	cpCmd.Stderr = os.Stderr
+	return cpCmd.Run()
+}
diff --git a/README.md b/README.md
index ae596e3..3c2e334 100644
--- a/README.md
+++ b/README.md
@@ -117,13 +117,15 @@ To configure Gogios, create a JSON configuration file (e.g., `/etc/gogios.json`)
       "Plugin": "/usr/local/libexec/nagios/check_ping",
       "Args": [ "-H", "www.foo.zone", "-4", "-w", "50,10%", "-c", "100,15%" ],
       "Retries": 3,
-      "RetryInterval": 10
+      "RetryInterval": 10,
+      "RandomSpread": 60
     },
     "Check ICMP6 www.foo.zone": {
       "Plugin": "/usr/local/libexec/nagios/check_ping",
-      "Args": [ "-H", "www.foo.zone", "-6", "-w", "50,10%", "-c", "100,15%" ]
+      "Args": [ "-H", "www.foo.zone", "-6", "-w", "50,10%", "-c", "100,15%" ],
       "Retries": 3,
-      "RetryInterval": 10
+      "RetryInterval": 10,
+      "RunInterval": 300
     },
     "www.foo.zone HTTP IPv4": {
       "Plugin": "/usr/local/libexec/nagios/check_http",
@@ -157,6 +159,10 @@ If you want to execute checks only when another check succeeded (status OK), use
 
 `Retries` and `RetryInterval` are optional check configuration parameters. In case of failure, Gogios will retry `Retries` times each `RetryInterval` seconds.
 
+`RandomSpread` is an optional check configuration parameter. It will cause a random sleep of up to N seconds (specified by config by each check) before the check is being executed. This is useful to avoid all checks running at the same time.
+
+`RunInterval` is an optional check configuration parameter. It defines the minimum interval in seconds between two executions of a check. This is useful if you run gogios more frequently than you want to run a specific check.
+
 For remote checks, use the `check_nrpe` plugin. You also need to have the NRPE server set up correctly on the target host (out of scope for this document).
 
 The `state.json` file mentioned above keeps track of the monitoring state and check results between Gogios runs, enabling Gogios only to send email notifications when there are changes in the check status.
@@ -202,4 +208,4 @@ My primary goal was to have a single email address for notifications and a simpl
 
 This led me to create Gogios, a lightweight monitoring tool tailored to my specific needs. I chose the Go programming language for this project as it allowed me to refresh my Go programming skills and provided a robust platform for developing a fast and efficient monitoring tool.
 
-Gogios eliminates unnecessary features and focuses on simplicity, providing a no-frills monitoring solution for small-scale self-hosted servers and virtual machines. The result is a tool that is easy to configure, set up, and maintain, ensuring that monitoring your resources is as hassle-free as possible.
+Gogios eliminates unnecessary features and focuses on simplicity, providing a no-frills monitoring solution for small-scale self-hosted servers and virtual machines. The result is a tool that is easy to configure, set up, and maintain, ensuring that monitoring your resources is as hassle-free as possible.
\ No newline at end of file
diff --git a/internal/check.go b/internal/check.go
index 70f0044..3f2e4cc 100644
--- a/internal/check.go
+++ b/internal/check.go
@@ -14,6 +14,8 @@ type check struct {
 	DependsOn     []string `json:"DependsOn,omitempty"`
 	Retries       int      `json:"Retries,omitempty"`
 	RetryInterval int      `json:"RetryInterval,omitempty"`
+	RunInterval   int      `json:"RunInterval,omitempty"`
+	RandomSpread  int      `json:"RandomSpread,omitempty"`
 }
 
 type namedCheck struct {
@@ -65,4 +67,4 @@ func (c namedCheck) run(ctx context.Context) checkResult {
 
 func (c namedCheck) skip(output string) checkResult {
 	return c.check.skip(c.name, output)
-}
+}
\ No newline at end of file
diff --git a/internal/runchecks.go b/internal/runchecks.go
index 788e77d..fb7a9c4 100644
--- a/internal/runchecks.go
+++ b/internal/runchecks.go
@@ -3,6 +3,7 @@ package internal
 import (
 	"context"
 	"log"
+	"math/rand"
 	"sync"
 	"time"
 )
@@ -36,6 +37,25 @@ func runChecks(ctx context.Context, state state, conf config) state {
 	inputWg.Add(len(conf.Checks))
 
 	for check := range inputCh {
+		if age := state.age(check.name); check.RunInterval > int(age.Seconds()) {
+			lastCheckState, ok := state.checks[check.name]
+			if ok {
+				log.Printf("Skipping %s: interval not yet reached (%v (%v) <= %v)", check.name,
+					int(age.Seconds()), age, check.RunInterval)
+				outputCh <- checkResult{
+					name:      check.name,
+					output:    lastCheckState.output,
+					epoch:     lastCheckState.Epoch,
+					status:    lastCheckState.Status,
+					federated: lastCheckState.federated,
+				}
+				inputWg.Done()
+				continue
+			}
+			log.Println("Something went wrong... expected check state for", check,
+				"bug got nothing! Proceeding anyway")
+		}
+
 		go func(check namedCheck) {
 			outputCh <- runCheck(ctx, limitCh, deps, check, conf, check.Retries)
 			inputWg.Done()
@@ -52,14 +72,20 @@ func runChecks(ctx context.Context, state state, conf config) state {
 	return state
 }
 
-func runCheck(ctx context.Context, limitCh chan struct{},
-	deps dependency, check namedCheck, conf config, retries int) checkResult {
-
+func runCheck(ctx context.Context, limitCh chan struct{}, deps dependency,
+	check namedCheck, conf config, retries int,
+) checkResult {
 	if err := deps.wait(ctx, check.DependsOn); err != nil {
 		deps.notOk(check.name)
 		return check.skip(err.Error())
 	}
 
+	if check.RandomSpread > 0 {
+		d := time.Duration(rand.Intn(check.RandomSpread)) * time.Second
+		log.Printf("Sleeping %v before running %s", d, check.name)
+		time.Sleep(d)
+	}
+
 	limitCh <- struct{}{}
 
 	checkCtx, cancel := context.WithTimeout(ctx,
@@ -84,4 +110,4 @@ func runCheck(ctx context.Context, limitCh chan struct{},
 
 	<-limitCh
 	return checkResult
-}
+}
\ No newline at end of file
diff --git a/internal/state.go b/internal/state.go
index 8de7f15..dceb108 100644
--- a/internal/state.go
+++ b/internal/state.go
@@ -83,6 +83,14 @@ func (s state) update(result checkResult) {
 	log.Println(result.name, cs)
 }
 
+func (s state) age(name string) time.Duration {
+	if prevState, ok := s.checks[name]; ok {
+		return time.Since(time.Unix(prevState.Epoch, 0))
+	}
+
+	return time.Duration(0)
+}
+
 // To be used to merge the state of another server running Gogios
 func (s state) merge(other state) error {
 	for name, cs := range other.checks {
@@ -105,7 +113,7 @@ func (s state) mergeFromBytes(bytes []byte) error {
 func (s state) persist() error {
 	stateDir := filepath.Dir(s.stateFile)
 	if _, err := os.Stat(stateDir); os.IsNotExist(err) {
-		if err := os.MkdirAll(stateDir, 0755); err != nil {
+		if err := os.MkdirAll(stateDir, 0o755); err != nil {
 			return err
 		}
 	}
@@ -180,8 +188,8 @@ func (s state) reportChanged(sb *strings.Builder) (changed bool) {
 }
 
 func (s state) reportUnhandled(sb *strings.Builder) (numCriticals, numWarnings,
-	numUnknown, numOK int) {
-
+	numUnknown, numOK int,
+) {
 	numCriticals = s.reportBy(sb, false, false, func(cs checkState) bool {
 		return cs.Status == nagiosCritical
 	})
@@ -208,8 +216,8 @@ func (s state) reportStaleAlerts(sb *strings.Builder) int {
 }
 
 func (s state) reportBy(sb *strings.Builder, showStatusChange, isStaleReport bool,
-	filter func(cs checkState) bool) (count int) {
-
+	filter func(cs checkState) bool,
+) (count int) {
 	for name, cs := range s.checks {
 		if !filter(cs) {
 			continue
@@ -254,4 +262,4 @@ func (s state) countBy(filter func(cs checkState) bool) (count int) {
 		}
 	}
 	return
-}
+}
\ No newline at end of file
diff --git a/internal/state_test.go b/internal/state_test.go
new file mode 100644
index 0000000..aacc023
--- /dev/null
+++ b/internal/state_test.go
@@ -0,0 +1,24 @@
+package internal
+
+import (
+	"testing"
+	"time"
+)
+
+func TestAge(t *testing.T) {
+	state := state{checks: make(map[string]checkState)}
+
+	state.checks["Check Foo"] = checkState{Epoch: 0}
+	minAge := time.Duration(time.Now().Unix())
+
+	if reportedAge := state.age("Check Foo"); reportedAge < minAge {
+		t.Errorf("expected age >= %v, got %v", minAge, reportedAge)
+	}
+
+	maxAge := time.Duration(time.Now().Unix())
+	state.checks["Check Bar"] = checkState{Epoch: time.Now().Unix()}
+
+	if reportedAge := state.age("Check Bar"); reportedAge >= minAge {
+		t.Errorf("expected age < %v, got %v", maxAge, reportedAge)
+	}
+}