Basic slack notification support

cmd/kured/Dockerfile

 FROM ubuntu
+RUN apt-get update && apt-get install -y ca-certificates && rm -rf /var/cache/apt
 ADD https://storage.googleapis.com/kubernetes-release/release/v1.4.8/bin/linux/amd64/kubectl /usr/bin/kubectl
 RUN chmod 0755 /usr/bin/kubectl
 COPY ./kured /usr/bin/kured

cmd/kured/main.go

@@ -16,6 +16,7 @@ import (
 	"github.com/weaveworks/kured/pkg/alerts"
 	"github.com/weaveworks/kured/pkg/daemonsetlock"
 	"github.com/weaveworks/kured/pkg/delaytick"
+	"github.com/weaveworks/kured/pkg/notifications/slack"
 )
 
 var (
@@ -27,6 +28,8 @@ var (
 	prometheusURL  string
 	alertFilter    *regexp.Regexp
 	rebootSentinel string
+	slackHookURL   string
+	slackUsername  string
 )
 
 func main() {
@@ -50,6 +53,11 @@ func main() {
 	rootCmd.PersistentFlags().StringVar(&rebootSentinel, "reboot-sentinel", "/var/run/reboot-required",
 		"path to file whose existence signals need to reboot")
 
+	rootCmd.PersistentFlags().StringVar(&slackHookURL, "slack-hook-url", "",
+		"slack hook URL for reboot notfications")
+	rootCmd.PersistentFlags().StringVar(&slackUsername, "slack-username", "kured",
+		"slack username for reboot notfications")
+
 	if err := rootCmd.Execute(); err != nil {
 		log.Fatal(err)
 	}
@@ -169,8 +177,15 @@ func waitForDrain(client *kubernetes.Clientset, nodeID string) {
 	}
 }
 
-func reboot() {
+func reboot(nodeID string) {
 	log.Infof("Commanding reboot")
+
+	if slackHookURL != "" {
+		if err := slack.NotifyReboot(slackHookURL, slackUsername, nodeID); err != nil {
+			log.Warnf("Error notifying slack: %v", err)
+		}
+	}
+
 	// Relies on /var/run/dbus/system_bus_socket bind mount to talk to systemd
 	rebootCmd := exec.Command("/bin/systemctl", "reboot")
 	if err := rebootCmd.Run(); err != nil {
@@ -237,7 +252,7 @@ func root(cmd *cobra.Command, args []string) {
 					drain(nodeID)
 					waitForDrain(client, nodeID)
 				}
-				reboot()
+				reboot(nodeID)
 				break
 			}
 		}

kured-ds.yaml

@@ -23,6 +23,7 @@ spec:
 #            - --period=60
 #            - --prometheus-url=http://prometheus.monitoring.svc.cluster.local
 #            - --reboot-sentinel=/var/run/reboot-required
+#            - --slack-hook-url=https://hooks.slack.com/...
           env:
             # Pass in the name of the node on which this pod is scheduled
             # for use with drain/uncordon operations and lock acquisition

pkg/notifications/slack/slack.go

+package slack
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+)
+
+var (
+	httpClient = &http.Client{Timeout: 5 * time.Second}
+)
+
+type body struct {
+	Text     string `json:"text,omitempty"`
+	Username string `json:"username,omitempty"`
+}
+
+func NotifyReboot(hookURL, username, nodeID string) error {
+	msg := body{
+		Text:     fmt.Sprintf("Rebooting node %s", nodeID),
+		Username: username,
+	}
+
+	var buf bytes.Buffer
+	if err := json.NewEncoder(&buf).Encode(&msg); err != nil {
+		return err
+	}
+
+	resp, err := httpClient.Post(hookURL, "application/json", &buf)
+	defer resp.Body.Close()
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		return fmt.Errorf(resp.Status)
+	}
+
+	return nil
+}