can keep state

6 files changed, 108 insertions, 24 deletions

diff --git a/check.go b/check.go
index b011eba..b98dd6a 100644
--- a/check.go
+++ b/check.go
@@ -3,7 +3,6 @@ package main
 import (
 	"bytes"
 	"context"
-	"log"
 	"os/exec"
 )
 
@@ -19,7 +18,6 @@ func (c check) execute(ctx context.Context) (string, int) {
 	var bytes bytes.Buffer
 	cmd.Stdout = &bytes
 	cmd.Stderr = &bytes
-	log.Println(ctx)
 
 	if err := cmd.Run(); err != nil {
 		if ctx.Err() == context.DeadlineExceeded {
diff --git a/config.go b/config.go
index b79e275..660b49d 100644
--- a/config.go
+++ b/config.go
@@ -14,7 +14,7 @@ type config struct {
 	SMTPServer    string `json:"omitempty"`
 	StateDir      string `json:"omitempty"`
 	CheckTimeoutS int
-	Checks        []check
+	Checks        map[string]check
 }
 
 func newConfig(configFile string) (config, error) {
@@ -53,13 +53,5 @@ func newConfig(configFile string) (config, error) {
 		log.Println("Set StateDir to " + config.StateDir)
 	}
 
-	dedup := make(map[string]interface{})
-	for _, check := range config.Checks {
-		if _, ok := dedup[check.Name]; ok {
-			return config, fmt.Errorf("Duplicate definition of check %s", check.Name)
-		}
-		dedup[check.Name] = struct{}{}
-	}
-
 	return config, nil
 }
diff --git a/gogios.json b/gogios.json
index 2f2dbe0..a6cbace 100644
--- a/gogios.json
+++ b/gogios.json
@@ -2,16 +2,22 @@
   "EmailTo": "paul",
   "EmailFrom": "gogios@buetow.org",
   "CheckTimeoutS": 10,
-  "Checks": [
-    {
-      "Name": "www.foo.zone HTTP IPv4",
+  "Checks": {
+    "foo.zone HTTP IPv4": {
+      "Plugin": "/usr/local/libexec/nagios/check_http",
+      "Args": ["foo.zone", "-4"]
+    },
+    "foo.zone HTTP IPv6": {
+      "Plugin": "/usr/local/libexec/nagios/check_http",
+      "Args": ["foo.zone", "-6"]
+    },
+    "www.foo.zone HTTP IPv4": {
       "Plugin": "/usr/local/libexec/nagios/check_http",
       "Args": ["www.foo.zone", "-4"]
     },
-    {
-      "Name": "www.foo.zone HTTP IPv6",
+    "www.foo.zone HTTP IPv6": {
       "Plugin": "/usr/local/libexec/nagios/check_http",
       "Args": ["www.foo.zone", "-6"]
     }
-  ]
+  }
 }
diff --git a/main.go b/main.go
index cf63a5f..d7df829 100644
--- a/main.go
+++ b/main.go
@@ -4,15 +4,11 @@ import (
 	"context"
 	"flag"
 	"fmt"
-	"log"
 	"time"
 )
 
 func main() {
-	log.Println("Welcome to Gogios!")
-
 	configFile := flag.String("cfg", "/etc/gogios.json", "The config file")
-
 	flag.Parse()
 
 	config, err := newConfig(*configFile)
@@ -20,14 +16,26 @@ func main() {
 		panic(err)
 	}
 
-	for _, check := range config.Checks {
+	state, err := newState(config)
+	if err != nil {
+		notifyError(config, err)
+	}
+
+	for name, check := range config.Checks {
 		ctx, cancel := context.WithTimeout(context.Background(),
 			time.Duration(config.CheckTimeoutS)*time.Second)
 		defer cancel()
 
-		if output, status := check.execute(ctx); status != ok {
+		output, status := check.execute(ctx)
+		stateChanged := state.update(name, status)
+
+		if status != ok || stateChanged {
 			subject := fmt.Sprintf("GOGIOS %s: %s", codeToString(status), check.Name)
 			notify(config, subject, output)
 		}
 	}
+
+	if err := state.persist(); err != nil {
+		notifyError(config, err)
+	}
 }
diff --git a/notify.go b/notify.go
index c31a242..3a295ba 100644
--- a/notify.go
+++ b/notify.go
@@ -26,3 +26,7 @@ func notify(config config, subject, body string) error {
 	return smtp.SendMail(config.SMTPServer, nil, config.EmailFrom,
 		[]string{config.EmailTo}, []byte(message))
 }
+
+func notifyError(config config, err error) error {
+	return notify(config, fmt.Sprintf("GOGIOS: An error occured: %v", err), err.Error())
+}
diff --git a/state.go b/state.go
index c3c7eab..67cb1d4 100644
--- a/state.go
+++ b/state.go
@@ -1,5 +1,81 @@
 package main
 
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+)
+
 type state struct {
-	Checks map[string]int
+	stateFile string
+	Checks    map[string]int
+}
+
+func newState(config config) (state, error) {
+	stateFile := fmt.Sprintf("%s/state.json", config.StateDir)
+	state := state{stateFile, make(map[string]int)}
+
+	if _, err := os.Stat(stateFile); err != nil {
+		return state, err
+	}
+
+	file, err := os.Open(stateFile)
+	if err != nil {
+		return state, err
+	}
+	defer file.Close()
+
+	// Read the file content
+	bytes, err := ioutil.ReadAll(file)
+	if err != nil {
+		return state, err
+	}
+
+	// Parse the JSON content
+	if err := json.Unmarshal(bytes, &state.Checks); err != nil {
+		return state, err
+	}
+
+	// Clean up obsolete state information
+	var obsolete []string
+	for name := range state.Checks {
+		if _, ok := config.Checks[name]; !ok {
+			obsolete = append(obsolete, name)
+		}
+	}
+
+	for _, name := range obsolete {
+		delete(state.Checks, name)
+		log.Printf("State of %s is obsolete (removed)", name)
+	}
+
+	return state, nil
+}
+
+func (s state) update(name string, status int) bool {
+	oldStatus, ok := s.Checks[name]
+	if !ok {
+		log.Printf("State of %s: %d (new)", name, status)
+		s.Checks[name] = status
+		return true
+	}
+
+	if oldStatus != status {
+		log.Printf("State of %s: %d -> %d (changed)", name, oldStatus, status)
+		s.Checks[name] = status
+		return true
+	}
+
+	log.Printf("State of %s: %d (unchanged)", name, status)
+	return false
+}
+
+func (s state) persist() error {
+	jsonData, err := json.Marshal(s.Checks)
+	if err != nil {
+		return err
+	}
+	return ioutil.WriteFile(s.stateFile, jsonData, os.ModePerm)
 }