kubeadm: allow kubeadm init to read config from file

cmd/kubeadm/app/cmd/init.go

@@ -19,6 +19,7 @@ package cmd
 import (
 	"fmt"
 	"io"
+	"io/ioutil"
 
 	"github.com/renstrom/dedent"
 	"github.com/spf13/cobra"
@@ -26,8 +27,10 @@ import (
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubemaster "k8s.io/kubernetes/cmd/kubeadm/app/master"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
+	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/cloudprovider"
 	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
+	"k8s.io/kubernetes/pkg/runtime"
 	netutil "k8s.io/kubernetes/pkg/util/net"
 )
 
@@ -44,12 +47,19 @@ var (
 // NewCmdInit returns "kubeadm init" command.
 func NewCmdInit(out io.Writer) *cobra.Command {
 	cfg := &kubeadmapi.MasterConfiguration{}
+	var cfgPath string
 	cmd := &cobra.Command{
 		Use:   "init",
 		Short: "Run this in order to set up the Kubernetes master.",
 		Run: func(cmd *cobra.Command, args []string) {
-			err := RunInit(out, cmd, args, cfg)
+			check := func(err error) {
-			cmdutil.CheckErr(err)
+				if err != nil {
+					cmdutil.CheckErr(fmt.Errorf("<cmd/init> %v", err))
+				}
+			}
+			i, err := NewInit(cfgPath, cfg)
+			check(err)
+			check(i.Run(out))
 		},
 	}
 
@@ -87,6 +97,8 @@ func NewCmdInit(out io.Writer) *cobra.Command {
 		`Choose a specific Kubernetes version for the control plane`,
 	)
 
+	cmd.PersistentFlags().StringVar(&cfgPath, "config", "", "Path to kubeadm config file")
+
 	// TODO (phase1+) @errordeveloper make the flags below not show up in --help but rather on --advanced-help
 	cmd.PersistentFlags().StringSliceVar(
 		&cfg.Etcd.Endpoints, "external-etcd-endpoints", []string{},
@@ -115,14 +127,26 @@ func NewCmdInit(out io.Writer) *cobra.Command {
 	return cmd
 }
 
-// RunInit executes master node provisioning, including certificates, needed static pod manifests, etc.
+type Init struct {
-func RunInit(out io.Writer, cmd *cobra.Command, args []string, cfg *kubeadmapi.MasterConfiguration) error {
+	cfg *kubeadmapi.MasterConfiguration
+}
+
+func NewInit(cfgPath string, cfg *kubeadmapi.MasterConfiguration) (*Init, error) {
+	if cfgPath != "" {
+		b, err := ioutil.ReadFile(cfgPath)
+		if err != nil {
+			return nil, fmt.Errorf("unable to read config from %q [%v]", cfgPath, err)
+		}
+		if err := runtime.DecodeInto(api.Codecs.UniversalDecoder(), b, cfg); err != nil {
+			return nil, fmt.Errorf("unable to decode config from %q [%v]", cfgPath, err)
+		}
+	}
 	// Auto-detect the IP
 	if len(cfg.API.AdvertiseAddresses) == 0 {
 		// TODO(phase1+) perhaps we could actually grab eth0 and eth1
 		ip, err := netutil.ChooseHostInterface()
 		if err != nil {
-			return err
+			return nil, err
 		}
 		cfg.API.AdvertiseAddresses = []string{ip.String()}
 	}
@@ -130,26 +154,31 @@ func RunInit(out io.Writer, cmd *cobra.Command, args []string, cfg *kubeadmapi.M
 	// TODO(phase1+) create a custom flag
 	if cfg.CloudProvider != "" {
 		if cloudprovider.IsCloudProvider(cfg.CloudProvider) {
-			fmt.Printf("<cmd/init> cloud provider %q initialized for the control plane. Remember to set the same cloud provider flag on the kubelet.\n", cfg.CloudProvider)
+			fmt.Printf("cloud provider %q initialized for the control plane. Remember to set the same cloud provider flag on the kubelet.\n", cfg.CloudProvider)
 		} else {
-			return fmt.Errorf("<cmd/init> cloud provider %q is not supported, you can use any of %v, or leave it unset.\n", cfg.CloudProvider, cloudprovider.CloudProviders())
+			return nil, fmt.Errorf("cloud provider %q is not supported, you can use any of %v, or leave it unset.\n", cfg.CloudProvider, cloudprovider.CloudProviders())
 		}
 	}
+	return &Init{cfg: cfg}, nil
+}
 
-	if err := kubemaster.CreateTokenAuthFile(&cfg.Secrets); err != nil {
+// RunInit executes master node provisioning, including certificates, needed static pod manifests, etc.
+func (i *Init) Run(out io.Writer) error {
+
+	if err := kubemaster.CreateTokenAuthFile(&i.cfg.Secrets); err != nil {
 		return err
 	}
 
-	if err := kubemaster.WriteStaticPodManifests(cfg); err != nil {
+	if err := kubemaster.WriteStaticPodManifests(i.cfg); err != nil {
 		return err
 	}
 
-	caKey, caCert, err := kubemaster.CreatePKIAssets(cfg)
+	caKey, caCert, err := kubemaster.CreatePKIAssets(i.cfg)
 	if err != nil {
 		return err
 	}
 
-	kubeconfigs, err := kubemaster.CreateCertsAndConfigForClients(cfg.API.AdvertiseAddresses, []string{"kubelet", "admin"}, caKey, caCert)
+	kubeconfigs, err := kubemaster.CreateCertsAndConfigForClients(i.cfg.API.AdvertiseAddresses, []string{"kubelet", "admin"}, caKey, caCert)
 	if err != nil {
 		return err
 	}
@@ -179,18 +208,18 @@ func RunInit(out io.Writer, cmd *cobra.Command, args []string, cfg *kubeadmapi.M
 		return err
 	}
 
-	if err := kubemaster.CreateDiscoveryDeploymentAndSecret(cfg, client, caCert); err != nil {
+	if err := kubemaster.CreateDiscoveryDeploymentAndSecret(i.cfg, client, caCert); err != nil {
 		return err
 	}
 
-	if err := kubemaster.CreateEssentialAddons(cfg, client); err != nil {
+	if err := kubemaster.CreateEssentialAddons(i.cfg, client); err != nil {
 		return err
 	}
 
 	// TODO(phase1+) use templates to reference struct fields directly as order of args is fragile
 	fmt.Fprintf(out, initDoneMsgf,
-		cfg.Secrets.GivenToken,
+		i.cfg.Secrets.GivenToken,
-		cfg.API.AdvertiseAddresses[0],
+		i.cfg.API.AdvertiseAddresses[0],
 	)
 
 	return nil