Added gcp-login command

cmd/k8s/gcp_login.go

@@ -0,0 +1,60 @@
+package main
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"path"
+	"text/template"
+
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/google"
+	"gopkg.in/alecthomas/kingpin.v2"
+
+	raw "google.golang.org/api/container/v1"
+)
+
+func gcpLogin(app *kingpin.Application, gcpProjectID, gcpZone, gkeCluster string) {
+	client, err := google.DefaultClient(oauth2.NoContext)
+	app.FatalIfError(err, "k8s")
+
+	svc, err := raw.New(client)
+	app.FatalIfError(err, "k8s")
+
+	cluster, err := svc.Projects.Zones.Clusters.Get(gcpProjectID, gcpZone, gkeCluster).Do()
+	app.FatalIfError(err, "k8s")
+
+	var buf bytes.Buffer
+	err = k8sConfigTmpl.Execute(&buf, cluster)
+	app.FatalIfError(err, "k8s")
+
+	err = os.MkdirAll(path.Join(os.Getenv("HOME"), ".kube"), 0755)
+	app.FatalIfError(err, "k8s")
+
+	err = ioutil.WriteFile(path.Join(os.Getenv("HOME"), ".kube/config"), buf.Bytes(), 0600)
+	app.FatalIfError(err, "k8s")
+}
+
+var k8sConfigTmpl = template.Must(template.New("").Parse(`
+apiVersion: v1
+kind: Config
+preferences: {}
+current-context: k8s-context
+- context:
+    cluster: k8s-cluster
+    user:    k8s-user
+  name: k8s-context
+clusters:
+- cluster:
+    certificate-authority-data: {{.MasterAuth.ClusterCaCertificate}}
+    server:                     https://{{.Endpoint}}
+  name: k8s-cluster
+contexts:
+users:
+- name: k8s-user
+  user:
+    client-certificate-data: {{.MasterAuth.ClientCertificate}}
+    client-key-data:         {{.MasterAuth.ClientKey}}
+    username: {{.MasterAuth.Username}}
+    password: {{.MasterAuth.Password}}
+`))

cmd/k8s/main.go

@@ -15,9 +15,25 @@ func main() {
 		secretDir      string
 		secretMapName  string
 		sourceFileName string
+		gcpProjectID   string
+		gkeClusterName string
+		gceZoneName    string
 	)
 
-	app := kingpin.New("k8s", "kubernetes utilities").Version(version.Get().String()).Author(version.Get().ReleasedBy)
+	app := kingpin.New("k8s", "kubernetes utilities").
+		Version(version.Get().String()).
+		Author(version.Get().ReleasedBy)
+
+	gcpLoginCmd := app.Command("gcp-login", "Login to a GKE cluster")
+	gcpLoginCmd.Flag("gcp-project", "GCP project id").Short('p').
+		PlaceHolder("GCP_PROJECT_ID").Envar("GCP_PROJECT_ID").
+		Required().StringVar(&gcpProjectID)
+	gcpLoginCmd.Flag("gce-zone", "GCE zone").Short('z').
+		PlaceHolder("GCE_ZONE").Envar("GCE_ZONE").
+		Required().StringVar(&gceZoneName)
+	gcpLoginCmd.Flag("gke-cluster", "GKE cluster name").Short('c').
+		PlaceHolder("GKE_CLUSTER").Envar("GKE_CLUSTER").
+		Required().StringVar(&gkeClusterName)
 
 	genConfigMapCmd := app.Command("gen-configmap", "Generate a ConfigMap from a directory")
 	genConfigMapCmd.Arg("config-directory", "Directory containing configuration").Default(".").ExistingDirVar(&configDir)
@@ -31,6 +47,8 @@ func main() {
 	genTemplateCmd.Arg("template", "Template file").Default(".").ExistingFileVar(&sourceFileName)
 
 	switch kingpin.MustParse(app.Parse(os.Args[1:])) {
+	case gcpLoginCmd.FullCommand():
+		gcpLogin(app, gcpProjectID, gceZoneName, gkeClusterName)
 	case genConfigMapCmd.FullCommand():
 		genConfigMap(app, configDir, configMapName)
 	case genSecretMapCmd.FullCommand():