Add simple healthz handler

README.md

@@ -96,6 +96,8 @@ If you want to increase or decrease the amount of chaos change the interval betw
 
 Remember that `chaoskube` by default kills any pod in all your namespaces, including system pods and itself.
 
+`chaoskube` provides a simple HTTP endpoint that can be used to check that it is running. This can be used for [Kubernetes liveness and readiness probes](https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-probes/). By default, this listens on port 8080. To disable, pass `--metrics-address=""` to `chaoskube`.
+
 ## Filtering targets
 
 However, you can limit the search space of `chaoskube` by providing label, annotation and namespace selectors.

main.go

@@ -1,7 +1,9 @@
 package main
 
 import (
+	"fmt"
 	"math/rand"
+	"net/http"
 	"os"
 	"time"
 
@@ -34,6 +36,7 @@ var (
 	interval           time.Duration
 	dryRun             bool
 	debug              bool
+	metricsAddress     string
 )
 
 func init() {
@@ -51,6 +54,7 @@ func init() {
 	kingpin.Flag("interval", "Interval between Pod terminations").Default("10m").DurationVar(&interval)
 	kingpin.Flag("dry-run", "If true, don't actually do anything.").Default("true").BoolVar(&dryRun)
 	kingpin.Flag("debug", "Enable debug logging.").BoolVar(&debug)
+	kingpin.Flag("metrics-address", "Listening address for metrics handler").Default(":8080").StringVar(&metricsAddress)
 }
 
 func main() {
@@ -149,6 +153,20 @@ func main() {
 		dryRun,
 	)
 
+	if metricsAddress != "" {
+		http.HandleFunc("/healthz",
+			func(w http.ResponseWriter, r *http.Request) {
+				fmt.Fprintln(w, "OK")
+			})
+		go func() {
+			if err := http.ListenAndServe(metricsAddress, nil); err != nil {
+				log.WithFields(log.Fields{
+					"err": err,
+				}).Fatal("failed to start HTTP server")
+			}
+		}()
+	}
+
 	for {
 		if err := chaoskube.TerminateVictim(); err != nil {
 			log.WithField("err", err).Error("failed to terminate victim")