feat: Adding kube-context flag + env var for tiller

This allows the kube-context for tiller's kube client to be set
at runtime via an env var (TILLER_KUBE_CONTEXT) or
CLI flag (--kube-context).

This can be useful when running tiller locally rather than inside the
cluster.

Signed-off-by: Adam Setters <9741640+asetty@users.noreply.github.com>

cmd/tiller/tiller.go

@@ -41,6 +41,7 @@ import (
 	// Import to initialize client auth plugins.
 	_ "k8s.io/client-go/plugin/pkg/client/auth"
 
+	"k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/helm/pkg/kube"
 	"k8s.io/helm/pkg/proto/hapi/services"
 	"k8s.io/helm/pkg/storage"
@@ -62,6 +63,8 @@ const (
 	tlsCertsEnvVar = "TILLER_TLS_CERTS"
 	// historyMaxEnvVar is the name of the env var for setting max history.
 	historyMaxEnvVar = "TILLER_HISTORY_MAX"
+	// k8sContextEnvVar is the name of the env var for the k8s context for tiller to use
+	kubeContextEnvVar = "TILLER_KUBE_CONTEXT"
 
 	storageMemory    = "memory"
 	storageConfigMap = "configmap"
@@ -79,6 +82,7 @@ var (
 	probeAddr     = flag.String("probe-listen", fmt.Sprintf(":%v", environment.DefaultTillerProbePort), "address:port to listen on for probes")
 	enableProbing = flag.Bool("probe", true, "enable probing over http")
 	enableTracing = flag.Bool("trace", false, "enable rpc tracing")
+	kubeContext   = flag.String("kube-context", kubeContextFromEnv(), "kube context for tiller")
 	store         = flag.String("storage", storageConfigMap, "storage driver to use. One of 'configmap', 'memory', 'sql' or 'secret'")
 
 	sqlDialect          = flag.String("sql-dialect", "postgres", "SQL dialect to use (only postgres is supported for now")
@@ -130,7 +134,12 @@ func start() {
 	healthSrv := health.NewServer()
 	healthSrv.SetServingStatus("Tiller", healthpb.HealthCheckResponse_NOT_SERVING)
 
-	clientset, err := kube.New(nil).KubernetesClientSet()
+	var clientArgs *genericclioptions.ConfigFlags = nil
+	if *kubeContext != "" {
+		clientArgs = genericclioptions.NewConfigFlags(false)
+		clientArgs.Context = kubeContext
+	}
+	clientset, err := kube.New(clientArgs).KubernetesClientSet()
 	if err != nil {
 		logger.Fatalf("Cannot initialize Kubernetes connection: %s", err)
 	}
@@ -168,7 +177,7 @@ func start() {
 		env.Releases.MaxHistory = *maxHistory
 	}
 
-	kubeClient := kube.New(nil)
+	kubeClient := kube.New(clientArgs)
 	kubeClient.Log = newLogger("kube").Printf
 	env.KubeClient = kubeClient
 
@@ -276,6 +285,10 @@ func namespace() string {
 	return environment.DefaultTillerNamespace
 }
 
+func kubeContextFromEnv() string {
+	return os.Getenv(kubeContextEnvVar)
+}
+
 func tlsOptions() tlsutil.Options {
 	opts := tlsutil.Options{CertFile: *certFile, KeyFile: *keyFile}
 	if *tlsVerify {