Introduce the --use flag when creating a cluster

cmd/kind/create/cluster/createcluster.go

@@ -36,6 +36,7 @@ type flagpole struct {
 	Config    string
 	ImageName string
 	Retain    bool
+	Use       bool
 	Wait      time.Duration
 }
 
@@ -55,6 +56,7 @@ func NewCommand() *cobra.Command {
 	cmd.Flags().StringVar(&flags.Config, "config", "", "path to a kind config file")
 	cmd.Flags().StringVar(&flags.ImageName, "image", "", "node docker image to use for booting the cluster")
 	cmd.Flags().BoolVar(&flags.Retain, "retain", false, "retain nodes for debugging when cluster creation fails")
+	cmd.Flags().BoolVar(&flags.Use, "use", false, "set KUBECONFIG to the configuration of this cluster, once it's created")
 	cmd.Flags().DurationVar(&flags.Wait, "wait", time.Duration(0), "Wait for control plane node to be ready (default 0s)")
 	return cmd
 }
@@ -106,6 +108,7 @@ func runE(flags *flagpole, cmd *cobra.Command, args []string) error {
 	if err = ctx.Create(cfg,
 		create.Retain(flags.Retain),
 		create.WaitForReady(flags.Wait),
+		create.Use(flags.Use),
 	); err != nil {
 		return errors.Wrap(err, "failed to create cluster")
 	}

pkg/cluster/create/cluster.go

@@ -41,6 +41,14 @@ func WaitForReady(interval time.Duration) ClusterOption {
 	}
 }
 
+// Use configures the cluster created to be active cluster after its creation
+func Use(use bool) ClusterOption {
+	return func(o *internalcreate.Options) *internalcreate.Options {
+		o.Use = use
+		return o
+	}
+}
+
 // SetupKubernetes configures create command to setup kubernetes after creating nodes containers
 // TODO: Refactor this. It is a temporary solution for a phased breakdown of different
 //      operations, specifically create. see https://github.com/kubernetes-sigs/kind/issues/324

pkg/cluster/internal/create/create.go

@@ -39,13 +39,15 @@ import (
 	"sigs.k8s.io/kind/pkg/cluster/internal/create/actions/kubeadmjoin"
 	"sigs.k8s.io/kind/pkg/cluster/internal/create/actions/loadbalancer"
 	"sigs.k8s.io/kind/pkg/cluster/internal/create/actions/waitforready"
+	"sigs.k8s.io/kind/pkg/util"
 )
 
 // Options holds cluster creation options
 // NOTE: this is only exported for usage by ./../create
 type Options struct {
 	Retain       bool
 	WaitForReady time.Duration
+	Use          bool
 	//TODO: Refactor this. It is a temporary solution for a phased breakdown of different
 	//      operations, specifically create. see https://github.com/kubernetes-sigs/kind/issues/324
 	SetupKubernetes bool // if kind should setup kubernetes after creating nodes
@@ -119,8 +121,49 @@ func Cluster(ctx *context.Context, cfg *config.Cluster, opts *Options) error {
 		return nil
 	}
 
-	// print how to set KUBECONFIG to point to the cluster etc.
-	printUsage(ctx.Name())
+	if opts.Use {
+		if err := setupKubeconfig(ctx, cfg); err != nil {
+			return err
+		}
+		printFootnote()
+	} else {
+		// print how to set KUBECONFIG to point to the cluster etc.
+		printUsage(ctx.Name())
+	}
+
+	return nil
+}
+
+func setupKubeconfig(ctx *context.Context, cfg *config.Cluster) error {
+
+	pki := util.NewKubeConfig()
+	certData, err := pki.CertData(ctx.KubeConfigPath())
+	if err != nil {
+		return err
+	}
+
+	pkiPaths, err := pki.CertDataPath(certData)
+	if err != nil {
+		return err
+	}
+
+	var server string
+	for _, v := range certData.Clusters {
+		server = v.Server
+	}
+
+	kcs := &util.KubeConfigSetup{
+		ClusterName:          ctx.Name(),
+		ClusterServerAddress: server,
+		ClientCertificate:    pkiPaths.ClientCertPath,
+		ClientKey:            pkiPaths.ClientKeyPath,
+		CertificateAuthority: pkiPaths.CertificateAuthorityPath,
+	}
+
+	kcs.SetKubeConfigFile(util.DefaultKubeconfigFile)
+	if err := util.SetupKubeConfig(kcs); err != nil {
+		return err
+	}
 
 	return nil
 }
@@ -162,3 +205,7 @@ func printSetupInstruction(name string) {
 		name,
 	)
 }
+
+func printFootnote() {
+	fmt.Print("\nYou can now use the cluster:\nkubectl cluster-info\n")
+}