#5: added readme and optimized a little bit

Author: angylada

README.md

@@ -1,22 +1,35 @@
 # Dovecot Director Controller
 
-Dovecot director is used to keep a temporary user -> mail server (= dovecot server) mapping, as described in <a href="https://wiki.dovecot.org/Director">dovecot docs</a>.
-If a dovecot director and dovecot server are used in a kubernetes cluster, mappings are not being updated in case a dovecot container restarts for example.
-To update the new pod ip and therefore to correct the mapping a manual execution of the command "doveadm reload" needs to be done on the dovecot director server.
-Since no one wants to waste manual effort on responses to ordinary container events this tool intends to automatically execute said command on the dovecot director shell whenever a dovecot container/pod becomes ready.
+Dovecot director is used to keep a temporary user -> mail server (= dovecot server) mapping, as described in
+[dovecot docs](https://wiki.dovecot.org/Director).
+
+If a dovecot director and dovecot server are used in a kubernetes cluster, mappings are not being updated in case a 
+dovecot container restarts for example since dovecot is not made to be used with private IPs as it is in k8s setup.
+To update the new pod ip and therefore to correct the mapping, a manual execution of the command `doveadm reload` needs 
+to be done on the dovecot director server.
+
+Since no one wants to waste manual effort on responses to ordinary container events this tool intends to automatically
+execute said command on the dovecot director pod container shell whenever a dovecot container/pod becomes ready 
+or when the tls secret is changed or updated.
 
 
 ### Usage
 
 Runs inside and outside of a kubernetes cluster.
+
 If you don't run it inside a k8s cluster it tries to load the kubeconfig in the executing users homedir.
 If it does not exist you need to specify the absolute path with command flag "-c".
 
 Environment variables needed for successful execution:
-* `DOVECOT_NAMESPACE`(string): Namespace name which must contain both dovecot director and dovecot pods
-* `DOVECOT_LABELS`(string): All labels given to dovecot for conclusive identification of dovecot pods, same format as in `DOVECOT_DIRECTOR_LABELS`
+* `DOVECOT_NAMESPACE`(string): Name of namespace that must contain both dovecot and dovecot director pods
 * `DOVECOT_DIRECTOR_LABELS`(string): All labels given to dovecot director for conclusive identification of dovecot director pods in the following format: `<LABEL1>=<VALUE1>,<LABEL2>=<VALUE2>`
-* `DOVECOT_DIRECTOR_CONTAINER_NAME` (string) (optional): Container Name of dovecot-director in Pod. Defaults to first Container in Pod if not set.
+* `DOVECOT_LABELS`(string): All labels given to dovecot for conclusive identification of dovecot pods, same format as in `DOVECOT_DIRECTOR_LABELS`
+
+  Optional environment parameters:
+* `DOVECOT_DIRECTOR_CONTAINER_NAME` (string) : Container Name of dovecot-director in Pod. Defaults to first Container in Pod if not set.
+* `SYNC_FREQUENCY_DURATION` (int, seconds, default: 70): This parameter is based on kubelets parameter `--sync-frequency duration` which is 
+    by default set to 60s, so if you change the value of kubelets parameter you should use the same value plus a few seconds
+    to trigger at `doveadm reload` after adding/changing tls secrets successfully
 
 ### Used Library
 https://github.com/kubernetes/client-go

cmd/main.go

@@ -42,8 +42,10 @@ func main() {
 	}
 	dovecotDirectorLabels = os.Getenv("DOVECOT_DIRECTOR_LABELS")
 	dovecotDirectorContainerName = os.Getenv("DOVECOT_DIRECTOR_CONTAINER_NAME")
-
+	dovecotLabels = os.Getenv("DOVECOT_LABELS")
+	namespace = os.Getenv("DOVECOT_NAMESPACE")
 	syncFrequencyDurationEnv := os.Getenv("SYNC_FREQUENCY_DURATION")
+
 	syncFrequencyDuration = 70
 	if syncFrequencyDurationEnv != "" {
 		syncFrequencyDuration, err = strconv.Atoi(syncFrequencyDurationEnv)
@@ -52,14 +54,10 @@ func main() {
 		}
 	}
 
-	dovecotLabels = os.Getenv("DOVECOT_LABELS")
-	namespace = os.Getenv("DOVECOT_NAMESPACE")
-
 	dovecotPods := GetPodsByLabel(clientset, namespace, dovecotLabels)
 	initialDovecotPodCount = len(dovecotPods.Items)
 
-	go StartWatcherSecret(clientset, namespace)
-	StartWatcherPods(clientset, namespace)
+	StartWatchers(clientset, namespace)
 }
 
 func GetPodsByLabel(clientset *kubernetes.Clientset, namespace string, labels string) *v1.PodList {
@@ -162,66 +160,57 @@ func ExecuteDoveAdm(clientset *kubernetes.Clientset, dovecotDirectorLabels strin
 	}
 }
 
-func StartWatcherPods(clientset *kubernetes.Clientset, namespace string) {
-	optionsModifierFunc := func(options *metav1.ListOptions) {
-		options.LabelSelector = dovecotLabels
-	}
-	watchlist := cache.NewFilteredListWatchFromClient(
+func StartWatchers(clientset *kubernetes.Clientset, namespace string) {
+	watchlistSecrets := cache.NewFilteredListWatchFromClient(
 		clientset.CoreV1().RESTClient(),
-		"pods",
+		"secrets",
 		namespace,
-		optionsModifierFunc)
-
-	_, controller := cache.NewInformer(
-		watchlist,
-		&v1.Pod{},
+		func(options *metav1.ListOptions) {},
+	)
+	_, controllerSecrets := cache.NewInformer(
+		watchlistSecrets,
+		&v1.Secret{},
 		time.Second*0,
 		cache.ResourceEventHandlerFuncs{
 			AddFunc: func(obj interface{}) {
-				pod := obj.(*v1.Pod)
-				handleEvent(pod, clientset)
+				secret := obj.(*v1.Secret)
+				if secret.Type == "kubernetes.io/tls" {
+					go ExecuteDoveAdm(clientset, dovecotDirectorLabels, syncFrequencyDuration)
+				}
 			},
 			UpdateFunc: func(oldObj, newObj interface{}) {
-				pod := newObj.(*v1.Pod)
-				handleEvent(pod, clientset)
+				secret := newObj.(*v1.Secret)
+				if secret.Type == "kubernetes.io/tls" {
+					go ExecuteDoveAdm(clientset, dovecotDirectorLabels, syncFrequencyDuration)
+				}
 			},
 		},
 	)
 
-	go controller.Run(make(chan struct{}))
-	for {
-		time.Sleep(time.Second)
-	}
-}
-
-func StartWatcherSecret(clientset *kubernetes.Clientset, namespace string) {
-	watchlist := cache.NewFilteredListWatchFromClient(
+	watchlistPods := cache.NewFilteredListWatchFromClient(
 		clientset.CoreV1().RESTClient(),
-		"secrets",
+		"pods",
 		namespace,
-		func(options *metav1.ListOptions) {})
+		func(options *metav1.ListOptions) { options.LabelSelector = dovecotLabels },
+	)
 
-	_, controller := cache.NewInformer(
-		watchlist,
-		&v1.Secret{},
+	_, controllerPods := cache.NewInformer(
+		watchlistPods,
+		&v1.Pod{},
 		time.Second*0,
 		cache.ResourceEventHandlerFuncs{
 			AddFunc: func(obj interface{}) {
-				secret := obj.(*v1.Secret)
-				if secret.Type == "kubernetes.io/tls" {
-					go ExecuteDoveAdm(clientset, dovecotDirectorLabels, syncFrequencyDuration)
-				}
+				handleEvent(obj.(*v1.Pod), clientset)
 			},
 			UpdateFunc: func(oldObj, newObj interface{}) {
-				secret := newObj.(*v1.Secret)
-				if secret.Type == "kubernetes.io/tls" {
-					go ExecuteDoveAdm(clientset, dovecotDirectorLabels, syncFrequencyDuration)
-				}
+				handleEvent(newObj.(*v1.Pod), clientset)
 			},
 		},
 	)
 
-	go controller.Run(make(chan struct{}))
+	go controllerPods.Run(make(chan struct{}))
+	go controllerSecrets.Run(make(chan struct{}))
+
 	for {
 		time.Sleep(time.Second)
 	}