Adds kubeadm images command

cmd/kubeadm/app/cmd/BUILD

@@ -124,3 +124,14 @@ filegroup(
     ],
     tags = ["automanaged"],
 )
+
+go_test(
+    name = "go_default_xtest",
+    srcs = ["config_test.go"],
+    deps = [
+        ":go_default_library",
+        "//cmd/kubeadm/app/apis/kubeadm/v1alpha1:go_default_library",
+        "//cmd/kubeadm/app/features:go_default_library",
+        "//vendor/github.com/renstrom/dedent:go_default_library",
+    ],
+)

cmd/kubeadm/app/cmd/config.go

@@ -19,17 +19,21 @@ package cmd
 import (
 	"fmt"
 	"io"
+	"strings"
 
 	"github.com/golang/glog"
 	"github.com/renstrom/dedent"
 	"github.com/spf13/cobra"
+	flag "github.com/spf13/pflag"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	clientset "k8s.io/client-go/kubernetes"
+	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmapiext "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	"k8s.io/kubernetes/cmd/kubeadm/app/features"
+	"k8s.io/kubernetes/cmd/kubeadm/app/images"
 	"k8s.io/kubernetes/cmd/kubeadm/app/phases/uploadconfig"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
 	configutil "k8s.io/kubernetes/cmd/kubeadm/app/util/config"
@@ -62,7 +66,7 @@ func NewCmdConfig(out io.Writer) *cobra.Command {
 
 	cmd.AddCommand(NewCmdConfigUpload(out, &kubeConfigFile))
 	cmd.AddCommand(NewCmdConfigView(out, &kubeConfigFile))
-
+	cmd.AddCommand(NewCmdConfigListImages(out))
 	return cmd
 }
 
@@ -201,3 +205,70 @@ func uploadConfiguration(client clientset.Interface, cfgPath string, defaultcfg
 	// Then just call the uploadconfig phase to do the rest of the work
 	return uploadconfig.UploadConfiguration(internalcfg, client)
 }
+
+// NewCmdConfigListImages returns the "kubeadm images" command
+func NewCmdConfigListImages(out io.Writer) *cobra.Command {
+	cfg := &kubeadmapiext.MasterConfiguration{}
+	kubeadmapiext.SetDefaults_MasterConfiguration(cfg)
+	var cfgPath, featureGatesString string
+	var err error
+
+	cmd := &cobra.Command{
+		Use:   "list-images",
+		Short: "Print a list of images kubeadm will use. The configuration file is used in case any images or image repositories are customized.",
+		Run: func(_ *cobra.Command, _ []string) {
+			if cfg.FeatureGates, err = features.NewFeatureGate(&features.InitFeatureGates, featureGatesString); err != nil {
+				kubeadmutil.CheckErr(err)
+			}
+			listImages, err := NewListImages(cfgPath, cfg)
+			kubeadmutil.CheckErr(err)
+			kubeadmutil.CheckErr(listImages.Run(out))
+		},
+	}
+	AddListImagesConfigFlag(cmd.PersistentFlags(), cfg, &featureGatesString)
+	AddListImagesFlags(cmd.PersistentFlags(), &cfgPath)
+
+	return cmd
+}
+
+// NewListImages returns a "kubeadm images" command
+func NewListImages(cfgPath string, cfg *kubeadmapiext.MasterConfiguration) (*ListImages, error) {
+	internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(cfgPath, cfg)
+	if err != nil {
+		return nil, fmt.Errorf("could not convert cfg to an internal cfg: %v", err)
+	}
+
+	return &ListImages{
+		cfg: internalcfg,
+	}, nil
+}
+
+// ListImages defines the struct used for "kubeadm images"
+type ListImages struct {
+	cfg *kubeadmapi.MasterConfiguration
+}
+
+// Run runs the images command and writes the result to the io.Writer passed in
+func (i *ListImages) Run(out io.Writer) error {
+	imgs := images.GetAllImages(i.cfg)
+	for _, img := range imgs {
+		fmt.Fprintln(out, img)
+	}
+
+	return nil
+}
+
+// AddListImagesConfigFlag adds the flags that configure kubeadm
+func AddListImagesConfigFlag(flagSet *flag.FlagSet, cfg *kubeadmapiext.MasterConfiguration, featureGatesString *string) {
+	flagSet.StringVar(
+		&cfg.KubernetesVersion, "kubernetes-version", cfg.KubernetesVersion,
+		`Choose a specific Kubernetes version for the control plane.`,
+	)
+	flagSet.StringVar(featureGatesString, "feature-gates", *featureGatesString, "A set of key=value pairs that describe feature gates for various features. "+
+		"Options are:\n"+strings.Join(features.KnownFeatures(&features.InitFeatureGates), "\n"))
+}
+
+// AddListImagesFlags adds the flag that defines the location of the config file
+func AddListImagesFlags(flagSet *flag.FlagSet, cfgPath *string) {
+	flagSet.StringVar(cfgPath, "config", *cfgPath, "Path to kubeadm config file.")
+}

cmd/kubeadm/app/cmd/config_test.go

+/*
+Copyright 2018 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package cmd_test
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"github.com/renstrom/dedent"
+
+	kubeadmapiext "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
+	"k8s.io/kubernetes/cmd/kubeadm/app/cmd"
+	"k8s.io/kubernetes/cmd/kubeadm/app/features"
+)
+
+const (
+	defaultNumberOfImages = 8
+)
+
+func TestNewCmdConfigListImages(t *testing.T) {
+	var output bytes.Buffer
+	images := cmd.NewCmdConfigListImages(&output)
+	images.Run(nil, nil)
+	actual := strings.Split(output.String(), "\n")
+	if len(actual) != defaultNumberOfImages {
+		t.Fatalf("Expected %v but found %v images", defaultNumberOfImages, len(actual))
+	}
+}
+
+func TestListImagesRunWithCustomConfigPath(t *testing.T) {
+	testcases := []struct {
+		name               string
+		expectedImageCount int
+		// each string provided here must appear in at least one image returned by Run
+		expectedImageSubstrings []string
+		configContents          []byte
+	}{
+		{
+			name:               "empty config contents",
+			expectedImageCount: defaultNumberOfImages,
+			configContents:     []byte{},
+		},
+		{
+			name:               "set k8s version",
+			expectedImageCount: defaultNumberOfImages,
+			expectedImageSubstrings: []string{
+				":v1.9.1",
+			},
+			configContents: []byte(dedent.Dedent(`
+				apiVersion: kubeadm.k8s.io/v1alpha1
+				kind: MasterConfiguration
+				kubernetesVersion: 1.9.1
+			`)),
+		},
+		{
+			name:               "use coredns",
+			expectedImageCount: defaultNumberOfImages,
+			expectedImageSubstrings: []string{
+				"coredns",
+			},
+			configContents: []byte(dedent.Dedent(`
+				apiVersion: kubeadm.k8s.io/v1alpha1
+				kind: MasterConfiguration
+				featureGates:
+				    CoreDNS: True
+			`)),
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			tmpDir, err := ioutil.TempDir("", "kubeadm-images-test")
+			if err != nil {
+				t.Fatalf("Unable to create temporary directory: %v", err)
+			}
+			defer os.RemoveAll(tmpDir)
+
+			configFilePath := filepath.Join(tmpDir, "test-config-file")
+			err = ioutil.WriteFile(configFilePath, tc.configContents, 0644)
+			if err != nil {
+				t.Fatalf("Failed writing a config file: %v", err)
+			}
+
+			i, err := cmd.NewListImages(configFilePath, &kubeadmapiext.MasterConfiguration{})
+			if err != nil {
+				t.Fatalf("Failed getting the kubeadm images command: %v", err)
+			}
+			var output bytes.Buffer
+			if i.Run(&output) != nil {
+				t.Fatalf("Error from running the images command: %v", err)
+			}
+			actual := strings.Split(output.String(), "\n")
+			if len(actual) != tc.expectedImageCount {
+				t.Fatalf("did not get the same number of images: actual: %v expected: %v. Actual value: %v", len(actual), tc.expectedImageCount, actual)
+			}
+
+			for _, substring := range tc.expectedImageSubstrings {
+				if !strings.Contains(output.String(), substring) {
+					t.Errorf("Expected to find %v but did not in this list of images: %v", substring, actual)
+				}
+			}
+		})
+	}
+}
+
+func TestConfigListImagesRunWithoutPath(t *testing.T) {
+	testcases := []struct {
+		name           string
+		cfg            kubeadmapiext.MasterConfiguration
+		expectedImages int
+	}{
+		{
+			name:           "empty config",
+			expectedImages: defaultNumberOfImages,
+		},
+		{
+			name: "external etcd configuration",
+			cfg: kubeadmapiext.MasterConfiguration{
+				Etcd: kubeadmapiext.Etcd{
+					Endpoints: []string{"hi"},
+				},
+			},
+			expectedImages: defaultNumberOfImages - 1,
+		},
+		{
+			name: "coredns enabled",
+			cfg: kubeadmapiext.MasterConfiguration{
+				FeatureGates: map[string]bool{
+					features.CoreDNS: true,
+				},
+			},
+			expectedImages: defaultNumberOfImages,
+		},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			i, err := cmd.NewListImages("", &tc.cfg)
+			if err != nil {
+				t.Fatalf("did not expect an error while creating the Images command: %v", err)
+			}
+
+			var output bytes.Buffer
+			if i.Run(&output) != nil {
+				t.Fatalf("did not expect an error running the Images command: %v", err)
+			}
+
+			actual := strings.Split(output.String(), "\n")
+			if len(actual) != tc.expectedImages {
+				t.Fatalf("expected %v images but got %v", tc.expectedImages, actual)
+			}
+		})
+	}
+}

cmd/kubeadm/app/images/BUILD

@@ -11,7 +11,10 @@ go_library(
     srcs = ["images.go"],
     importpath = "k8s.io/kubernetes/cmd/kubeadm/app/images",
     deps = [
+        "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
         "//cmd/kubeadm/app/constants:go_default_library",
+        "//cmd/kubeadm/app/features:go_default_library",
+        "//cmd/kubeadm/app/phases/addons/dns:go_default_library",
         "//cmd/kubeadm/app/util:go_default_library",
     ],
 )

cmd/kubeadm/app/images/images.go

@@ -20,7 +20,10 @@ import (
 	"fmt"
 	"runtime"
 
+	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
+	"k8s.io/kubernetes/cmd/kubeadm/app/features"
+	"k8s.io/kubernetes/cmd/kubeadm/app/phases/addons/dns"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
 )
 
@@ -42,3 +45,25 @@ func GetCoreImage(image, repoPrefix, k8sVersion, overrideImage string) string {
 		constants.KubeScheduler:         fmt.Sprintf("%s/%s-%s:%s", repoPrefix, "kube-scheduler", runtime.GOARCH, kubernetesImageTag),
 	}[image]
 }
+
+// GetAllImages returns a list of container images kubeadm expects to use on a control plane node
+func GetAllImages(cfg *kubeadmapi.MasterConfiguration) []string {
+	imgs := []string{}
+	imgs = append(imgs, GetCoreImage(constants.KubeAPIServer, cfg.ImageRepository, cfg.KubernetesVersion, cfg.UnifiedControlPlaneImage))
+	imgs = append(imgs, GetCoreImage(constants.KubeControllerManager, cfg.ImageRepository, cfg.KubernetesVersion, cfg.UnifiedControlPlaneImage))
+	imgs = append(imgs, GetCoreImage(constants.KubeScheduler, cfg.ImageRepository, cfg.KubernetesVersion, cfg.UnifiedControlPlaneImage))
+	imgs = append(imgs, fmt.Sprintf("%v/%v-%v:%v", cfg.ImageRepository, constants.KubeProxy, runtime.GOARCH, kubeadmutil.KubernetesVersionToImageTag(cfg.KubernetesVersion)))
+	imgs = append(imgs, fmt.Sprintf("%v/pause-%v:%v", cfg.ImageRepository, runtime.GOARCH, "3.1"))
+
+	// if etcd is not external then add the image as it will be required
+	if len(cfg.Etcd.Endpoints) == 0 {
+		imgs = append(imgs, GetCoreImage(constants.Etcd, cfg.ImageRepository, cfg.KubernetesVersion, cfg.Etcd.Image))
+	}
+
+	dnsImage := fmt.Sprintf("%v/k8s-dns-kube-dns-%v:%v", cfg.ImageRepository, runtime.GOARCH, dns.GetDNSVersion(nil, constants.KubeDNS))
+	if features.Enabled(cfg.FeatureGates, features.CoreDNS) {
+		dnsImage = fmt.Sprintf("coredns/coredns:%v", dns.GetDNSVersion(nil, constants.CoreDNS))
+	}
+	imgs = append(imgs, dnsImage)
+	return imgs
+}

docs/.generated_docs

@@ -58,6 +58,7 @@ docs/admin/kubeadm_alpha_phase_selfhosting_convert-from-staticpods.md
 docs/admin/kubeadm_alpha_phase_upload-config.md
 docs/admin/kubeadm_completion.md
 docs/admin/kubeadm_config.md
+docs/admin/kubeadm_config_list-images.md
 docs/admin/kubeadm_config_upload.md
 docs/admin/kubeadm_config_upload_from-file.md
 docs/admin/kubeadm_config_upload_from-flags.md
@@ -132,6 +133,7 @@ docs/man/man1/kubeadm-alpha-phase-upload-config.1
 docs/man/man1/kubeadm-alpha-phase.1
 docs/man/man1/kubeadm-alpha.1
 docs/man/man1/kubeadm-completion.1
+docs/man/man1/kubeadm-config-list-images.1
 docs/man/man1/kubeadm-config-upload-from-file.1
 docs/man/man1/kubeadm-config-upload-from-flags.1
 docs/man/man1/kubeadm-config-upload.1

docs/admin/kubeadm_config_list-images.md

+This file is autogenerated, but we've stopped checking such files into the
+repository to reduce the need for rebases. Please run hack/generate-docs.sh to
+populate this file.

docs/man/man1/kubeadm-config-list-images.1

+This file is autogenerated, but we've stopped checking such files into the
+repository to reduce the need for rebases. Please run hack/generate-docs.sh to
+populate this file.