Allow to configure clustername in creation of kubeconfig using kubeadm command

Signed-off-by: Prabhu Jayakumar <j.prabhu91@gmail.com>

cmd/kubeadm/app/cmd/alpha/kubeconfig.go

@@ -99,6 +99,7 @@ func newCmdUserKubeConfig(out io.Writer) *cobra.Command {
 
 	// Add ClusterConfiguration backed flags to the command
 	cmd.Flags().StringVar(&clusterCfg.CertificatesDir, options.CertificatesDir, clusterCfg.CertificatesDir, "The path where certificates are stored")
+	cmd.Flags().StringVar(&clusterCfg.ClusterName, "cluster-name", clusterCfg.ClusterName, "Cluster name to be used in kubeconfig")
 
 	// Add InitConfiguration backed flags to the command
 	cmd.Flags().StringVar(&initCfg.LocalAPIEndpoint.AdvertiseAddress, options.APIServerAdvertiseAddress, initCfg.LocalAPIEndpoint.AdvertiseAddress, "The IP address the API server is accessible on")

cmd/kubeadm/app/cmd/alpha/kubeconfig_test.go

@@ -56,6 +56,7 @@ func TestKubeConfigSubCommandsThatWritesToOut(t *testing.T) {
 		command         string
 		withClientCert  bool
 		withToken       bool
+		withClusterName bool
 		additionalFlags []string
 	}{
 		{
@@ -63,12 +64,26 @@ func TestKubeConfigSubCommandsThatWritesToOut(t *testing.T) {
 			command:        "user",
 			withClientCert: true,
 		},
+		{
+			name:            "user subCommand withClientCert",
+			command:         "user",
+			withClientCert:  true,
+			withClusterName: true,
+			additionalFlags: []string{"--cluster-name=my-cluster"},
+		},
 		{
 			name:            "user subCommand withToken",
 			withToken:       true,
 			command:         "user",
 			additionalFlags: []string{"--token=123456"},
 		},
+		{
+			name:            "user subCommand withToken",
+			withToken:       true,
+			command:         "user",
+			withClusterName: true,
+			additionalFlags: []string{"--token=123456", "--cluster-name=my-cluster"},
+		},
 	}
 
 	for _, test := range tests {
@@ -104,6 +119,11 @@ func TestKubeConfigSubCommandsThatWritesToOut(t *testing.T) {
 				// checks that kubeconfig files have expected token
 				kubeconfigtestutil.AssertKubeConfigCurrentAuthInfoWithToken(t, config, "myUser", "123456")
 			}
+
+			if test.withClusterName {
+				// checks that kubeconfig files have expected cluster name
+				kubeconfigtestutil.AssertKubeConfigCurrentContextWithClusterName(t, config, "my-cluster")
+			}
 		})
 	}
 }

cmd/kubeadm/test/kubeconfig/util.go

@@ -98,3 +98,15 @@ func AssertKubeConfigCurrentAuthInfoWithToken(t *testing.T, config *clientcmdapi
 		return
 	}
 }
+
+// AssertKubeConfigCurrentContextWithClusterName is a utility function for kubeadm testing that asserts if the Current Cluster config in
+// the given KubeConfig object refers to expected cluster name
+func AssertKubeConfigCurrentContextWithClusterName(t *testing.T, config *clientcmdapi.Config, expectedClusterName string) {
+	currentContext := config.Contexts[config.CurrentContext]
+
+	// assert cluster name
+	if currentContext.Cluster != expectedClusterName {
+		t.Errorf("kubeconfig.currentContext.clusterName [%s], expected [%s]", currentContext.Cluster, expectedClusterName)
+		return
+	}
+}