options, app: - Handle more config errors

- Add --help/-h for usage information

app/options/options.go

@@ -7,6 +7,7 @@ import (
 )
 
 type KubeRouterConfig struct {
+	HelpRequested      bool
 	Kubeconfig         string
 	Master             string
 	ConfigSyncPeriod   time.Duration
@@ -41,6 +42,7 @@ func NewKubeRouterConfig() *KubeRouterConfig {
 }
 
 func (s *KubeRouterConfig) AddFlags(fs *pflag.FlagSet) {
+	fs.BoolVarP(&s.HelpRequested, "help", "h", false, "Print usage information.")
 	fs.BoolVar(&s.RunServiceProxy, "run-service-proxy", s.RunServiceProxy, "If false, kube-router wont setup IPVS for services proxy. True by default.")
 	fs.BoolVar(&s.RunFirewall, "run-firewall", s.RunFirewall, "If false, kube-router wont setup iptables to provide ingress firewall for pods. True by default.")
 	fs.BoolVar(&s.RunRouter, "run-router", s.RunRouter, "If true each node advertise routes the rest of the nodes and learn the routes for the pods. True by default.")

app/server.go

@@ -24,19 +24,19 @@ func NewKubeRouterDefault(config *options.KubeRouterConfig) (*KubeRouter, error)
 
 	if len(config.Master) == 0 && len(config.Kubeconfig) == 0 {
 		if _, err := os.Stat("/var/lib/kube-router/kubeconfig"); os.IsNotExist(err) {
-			panic("Either one of --master or --kubeconfig must be specified. Or valid kubeconfig file must exist as /var/lib/kube-router/kubeconfig")
+			return nil, errors.New("Either one of --master or --kubeconfig must be specified. Or valid kubeconfig file must exist as /var/lib/kube-router/kubeconfig")
 		}
 		config.Kubeconfig = "/var/lib/kube-router/kubeconfig"
 	}
 
 	clientconfig, err := clientcmd.BuildConfigFromFlags(config.Master, config.Kubeconfig)
 	if err != nil {
-		panic(err.Error())
+		return nil, errors.New("Failed to build configuration from CLI: " + err.Error())
 	}
 
 	clientset, err := kubernetes.NewForConfig(clientconfig)
 	if err != nil {
-		panic(err.Error())
+		return nil, errors.New("Failed to create Kubernetes client: " + err.Error())
 	}
 
 	return &KubeRouter{Client: clientset, Config: config}, nil
@@ -108,7 +108,7 @@ func (kr *KubeRouter) Run() error {
 
 	err = kr.startApiWatchers()
 	if err != nil {
-		panic("Failed to start API watchers: " + err.Error())
+		return errors.New("Failed to start API watchers: " + err.Error())
 	}
 
 	if !(kr.Config.RunFirewall || kr.Config.RunServiceProxy || kr.Config.RunRouter) {
@@ -119,7 +119,7 @@ func (kr *KubeRouter) Run() error {
 	if kr.Config.RunFirewall {
 		npc, err := controllers.NewNetworkPolicyController(kr.Client, kr.Config)
 		if err != nil {
-			panic("Failed to create network policy controller: " + err.Error())
+			return errors.New("Failed to create network policy controller: " + err.Error())
 		}
 		npcStopCh = make(chan struct{})
 		wg.Add(1)
@@ -129,7 +129,7 @@ func (kr *KubeRouter) Run() error {
 	if kr.Config.RunRouter {
 		nrc, err := controllers.NewNetworkRoutingController(kr.Client, kr.Config)
 		if err != nil {
-			panic("Failed to create network routing controller: " + err.Error())
+			return errors.New("Failed to create network routing controller: " + err.Error())
 		}
 		nrcStopCh = make(chan struct{})
 		wg.Add(1)
@@ -139,7 +139,7 @@ func (kr *KubeRouter) Run() error {
 	if kr.Config.RunServiceProxy {
 		nsc, err := controllers.NewNetworkServicesController(kr.Client, kr.Config)
 		if err != nil {
-			panic("Failed to create network services controller: " + err.Error())
+			return errors.New("Failed to create network services controller: " + err.Error())
 		}
 		nscStopCh = make(chan struct{})
 		wg.Add(1)

kube-router.go

@@ -18,8 +18,13 @@ func main() {
 
 	flag.Set("logtostderr", "true")
 
+	if config.HelpRequested {
+		pflag.Usage()
+		os.Exit(0)
+	}
+
 	if os.Geteuid() != 0 {
-		fmt.Fprintf(os.Stderr, "kube-router need to be run by user with previlages to execute iptables, ipset and configure ipvs\n")
+		fmt.Fprintf(os.Stderr, "kube-router needs to be run with privileges to execute iptables, ipset and configure ipvs\n")
 		os.Exit(1)
 	}
 
@@ -34,7 +39,8 @@ func main() {
 		os.Exit(1)
 	}
 
-	if err = kubeRouter.Run(); err != nil {
+	err = kubeRouter.Run()
+	if err != nil {
 		fmt.Fprintf(os.Stderr, "Failed to run kube-router: %v\n", err)
 		os.Exit(1)
 	}