Refactor a bit of the config YAML loading code, and support loading multiple YAML documents

cmd/kubeadm/app/cmd/config.go

@@ -17,6 +17,7 @@ limitations under the License.
 package cmd
 
 import (
+	"bytes"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -28,6 +29,7 @@ import (
 	flag "github.com/spf13/pflag"
 
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime"
 	clientset "k8s.io/client-go/kubernetes"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmscheme "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/scheme"
@@ -44,14 +46,8 @@ import (
 	utilsexec "k8s.io/utils/exec"
 )
 
-const (
-	// TODO: Figure out how to get these constants from the API machinery
-	masterConfig = "MasterConfiguration"
-	nodeConfig   = "NodeConfiguration"
-)
-
 var (
-	availableAPIObjects = []string{masterConfig, nodeConfig}
+	availableAPIObjects = []string{constants.MasterConfigurationKind, constants.NodeConfigurationKind}
 	// sillyToken is only set statically to make kubeadm not randomize the token on every run
 	sillyToken = kubeadmapiv1alpha3.BootstrapToken{
 		Token: &kubeadmapiv1alpha3.BootstrapTokenString{
@@ -110,16 +106,13 @@ func NewCmdConfigPrintDefault(out io.Writer) *cobra.Command {
 			if len(apiObjects) == 0 {
 				apiObjects = availableAPIObjects
 			}
-			for i, apiObject := range apiObjects {
-				if i > 0 {
-					fmt.Fprintln(out, "---")
-				}
-
+			allBytes := [][]byte{}
+			for _, apiObject := range apiObjects {
 				cfgBytes, err := getDefaultAPIObjectBytes(apiObject)
 				kubeadmutil.CheckErr(err)
-				// Print the API object byte array
-				fmt.Fprintf(out, "%s", cfgBytes)
+				allBytes = append(allBytes, cfgBytes)
 			}
+			fmt.Fprint(out, string(bytes.Join(allBytes, []byte(constants.YAMLDocumentSeparator))))
 		},
 	}
 	cmd.Flags().StringSliceVar(&apiObjects, "api-objects", apiObjects,
@@ -128,26 +121,29 @@ func NewCmdConfigPrintDefault(out io.Writer) *cobra.Command {
 }
 
 func getDefaultAPIObjectBytes(apiObject string) ([]byte, error) {
-	if apiObject == masterConfig {
-
-		internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig("", &kubeadmapiv1alpha3.MasterConfiguration{
-			BootstrapTokens: []kubeadmapiv1alpha3.BootstrapToken{sillyToken},
+	var internalcfg runtime.Object
+	var err error
+	switch apiObject {
+	case constants.MasterConfigurationKind:
+		internalcfg, err = configutil.ConfigFileAndDefaultsToInternalConfig("", &kubeadmapiv1alpha3.MasterConfiguration{
+			API:               kubeadmapiv1alpha3.API{AdvertiseAddress: "1.2.3.4"},
+			BootstrapTokens:   []kubeadmapiv1alpha3.BootstrapToken{sillyToken},
+			KubernetesVersion: fmt.Sprintf("v1.%d.0", constants.MinimumControlPlaneVersion.Minor()+1),
 		})
-		kubeadmutil.CheckErr(err)
-
-		return kubeadmutil.MarshalToYamlForCodecs(internalcfg, kubeadmapiv1alpha3.SchemeGroupVersion, kubeadmscheme.Codecs)
-	}
-	if apiObject == nodeConfig {
-		internalcfg, err := configutil.NodeConfigFileAndDefaultsToInternalConfig("", &kubeadmapiv1alpha3.NodeConfiguration{
+	case constants.NodeConfigurationKind:
+		internalcfg, err = configutil.NodeConfigFileAndDefaultsToInternalConfig("", &kubeadmapiv1alpha3.NodeConfiguration{
 			Token: sillyToken.Token.String(),
 			DiscoveryTokenAPIServers:               []string{"kube-apiserver:6443"},
 			DiscoveryTokenUnsafeSkipCAVerification: true,
 		})
-		kubeadmutil.CheckErr(err)
-
-		return kubeadmutil.MarshalToYamlForCodecs(internalcfg, kubeadmapiv1alpha3.SchemeGroupVersion, kubeadmscheme.Codecs)
+		// TODO: DiscoveryTokenUnsafeSkipCAVerification: true needs to be set for validation to pass, but shouldn't be recommended as the default
+	default:
+		err = fmt.Errorf("--api-object needs to be one of %v", availableAPIObjects)
 	}
-	return []byte{}, fmt.Errorf("--api-object needs to be one of %v", availableAPIObjects)
+	if err != nil {
+		return []byte{}, err
+	}
+	return kubeadmutil.MarshalToYamlForCodecs(internalcfg, kubeadmapiv1alpha3.SchemeGroupVersion, kubeadmscheme.Codecs)
 }
 
 // NewCmdConfigMigrate returns cobra.Command for "kubeadm config migrate" command
@@ -176,31 +172,12 @@ func NewCmdConfigMigrate(out io.Writer) *cobra.Command {
 				kubeadmutil.CheckErr(fmt.Errorf("The --old-config flag is mandatory"))
 			}
 
-			b, err := ioutil.ReadFile(oldCfgPath)
+			internalcfg, err := configutil.AnyConfigFileAndDefaultsToInternal(oldCfgPath)
 			kubeadmutil.CheckErr(err)
 
-			var outputBytes []byte
-			gvk, err := kubeadmutil.GroupVersionKindFromBytes(b, kubeadmscheme.Codecs)
+			outputBytes, err := kubeadmutil.MarshalToYamlForCodecs(internalcfg, kubeadmapiv1alpha3.SchemeGroupVersion, kubeadmscheme.Codecs)
 			kubeadmutil.CheckErr(err)
 
-			switch gvk.Kind {
-			case masterConfig:
-				internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(oldCfgPath, &kubeadmapiv1alpha3.MasterConfiguration{})
-				kubeadmutil.CheckErr(err)
-
-				outputBytes, err = kubeadmutil.MarshalToYamlForCodecs(internalcfg, kubeadmapiv1alpha3.SchemeGroupVersion, kubeadmscheme.Codecs)
-				kubeadmutil.CheckErr(err)
-			case nodeConfig:
-				internalcfg, err := configutil.NodeConfigFileAndDefaultsToInternalConfig(oldCfgPath, &kubeadmapiv1alpha3.NodeConfiguration{})
-				kubeadmutil.CheckErr(err)
-
-				// TODO: In the future we might not want to duplicate these two lines of code for every case here.
-				outputBytes, err = kubeadmutil.MarshalToYamlForCodecs(internalcfg, kubeadmapiv1alpha3.SchemeGroupVersion, kubeadmscheme.Codecs)
-				kubeadmutil.CheckErr(err)
-			default:
-				kubeadmutil.CheckErr(fmt.Errorf("Didn't recognize type with GroupVersionKind: %v", gvk))
-			}
-
 			if newCfgPath == "" {
 				fmt.Fprint(out, string(outputBytes))
 			} else {

cmd/kubeadm/app/cmd/phases/kubelet.go

@@ -18,12 +18,10 @@ package phases
 
 import (
 	"fmt"
-	"io/ioutil"
 
 	"github.com/spf13/cobra"
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
-	kubeadmscheme "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/scheme"
 	kubeadmapiv1alpha3 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha3"
 	"k8s.io/kubernetes/cmd/kubeadm/app/cmd/options"
 	cmdutil "k8s.io/kubernetes/cmd/kubeadm/app/cmd/util"
@@ -38,12 +36,6 @@ import (
 	utilsexec "k8s.io/utils/exec"
 )
 
-const (
-	// TODO: Figure out how to get these constants from the API machinery
-	masterConfig = "MasterConfiguration"
-	nodeConfig   = "NodeConfiguration"
-)
-
 var (
 	kubeletWriteEnvFileLongDesc = normalizer.LongDesc(`
 		Writes an environment file with flags that should be passed to the kubelet executing on the master or node.
@@ -56,7 +48,7 @@ var (
 		kubeadm alpha phase kubelet write-env-file --config masterconfig.yaml
 
 		# Writes a dynamic environment file with kubelet flags from a NodeConfiguration file.
-		kubeadm alpha phase kubelet write-env-file --config nodeConfig.yaml
+		kubeadm alpha phase kubelet write-env-file --config nodeconfig.yaml
 		`)
 
 	kubeletConfigUploadLongDesc = normalizer.LongDesc(`
@@ -144,12 +136,7 @@ func NewCmdKubeletWriteEnvFile() *cobra.Command {
 
 // RunKubeletWriteEnvFile is the function that is run when "kubeadm phase kubelet write-env-file" is executed
 func RunKubeletWriteEnvFile(cfgPath string) error {
-	b, err := ioutil.ReadFile(cfgPath)
-	if err != nil {
-		return err
-	}
-
-	gvk, err := kubeadmutil.GroupVersionKindFromBytes(b, kubeadmscheme.Codecs)
+	internalcfg, err := configutil.AnyConfigFileAndDefaultsToInternal(cfgPath)
 	if err != nil {
 		return err
 	}
@@ -157,30 +144,18 @@ func RunKubeletWriteEnvFile(cfgPath string) error {
 	var nodeRegistrationObj *kubeadmapi.NodeRegistrationOptions
 	var featureGates map[string]bool
 	var registerWithTaints bool
-	switch gvk.Kind {
-	case masterConfig:
-		internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(cfgPath, &kubeadmapiv1alpha3.MasterConfiguration{})
-		if err != nil {
-			return err
-		}
-		nodeRegistrationObj = &internalcfg.NodeRegistration
-		featureGates = internalcfg.FeatureGates
+
+	switch cfg := internalcfg.(type) {
+	case *kubeadmapi.MasterConfiguration:
+		nodeRegistrationObj = &cfg.NodeRegistration
+		featureGates = cfg.FeatureGates
 		registerWithTaints = false
-	case nodeConfig:
-		internalcfg, err := configutil.NodeConfigFileAndDefaultsToInternalConfig(cfgPath, &kubeadmapiv1alpha3.NodeConfiguration{})
-		if err != nil {
-			return err
-		}
-		nodeRegistrationObj = &internalcfg.NodeRegistration
-		featureGates = internalcfg.FeatureGates
+	case *kubeadmapi.NodeConfiguration:
+		nodeRegistrationObj = &cfg.NodeRegistration
+		featureGates = cfg.FeatureGates
 		registerWithTaints = true
 	default:
-		if err != nil {
-			return fmt.Errorf("Didn't recognize type with GroupVersionKind: %v", gvk)
-		}
-	}
-	if nodeRegistrationObj == nil {
-		return fmt.Errorf("couldn't load nodeRegistration field from config file")
+		return fmt.Errorf("couldn't read config file, no matching kind found")
 	}
 
 	if err := kubeletphase.WriteKubeletDynamicEnvFile(nodeRegistrationObj, featureGates, registerWithTaints, constants.KubeletRunDirectory); err != nil {

cmd/kubeadm/app/constants/constants.go

@@ -285,6 +285,16 @@ const (
 
 	// CoreDNSVersion is the version of CoreDNS to be deployed if it is used
 	CoreDNSVersion = "1.1.3"
+
+	// MasterConfigurationKind is the string kind value for the MasterConfiguration struct
+	MasterConfigurationKind = "MasterConfiguration"
+
+	// NodeConfigurationKind is the string kind value for the MasterConfiguration struct
+	NodeConfigurationKind = "NodeConfiguration"
+
+	// YAMLDocumentSeparator is the separator for YAML documents
+	// TODO: Find a better place for this constant
+	YAMLDocumentSeparator = "---\n"
 )
 
 var (

cmd/kubeadm/app/util/config/common.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 config
+
+import (
+	"fmt"
+	"io/ioutil"
+	"strings"
+
+	"github.com/golang/glog"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+	kubeadmapiv1alpha3 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha3"
+	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
+	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
+	"k8s.io/kubernetes/pkg/util/version"
+)
+
+// AnyConfigFileAndDefaultsToInternal reads either a MasterConfiguration or NodeConfiguration and unmarshals it
+func AnyConfigFileAndDefaultsToInternal(cfgPath string) (runtime.Object, error) {
+	b, err := ioutil.ReadFile(cfgPath)
+	if err != nil {
+		return nil, err
+	}
+
+	gvks, err := kubeadmutil.GroupVersionKindsFromBytes(b)
+	if err != nil {
+		return nil, err
+	}
+
+	// First, check if the gvk list has MasterConfiguration and in that case try to unmarshal it
+	if kubeadmutil.GroupVersionKindsHasMasterConfiguration(gvks) {
+		return ConfigFileAndDefaultsToInternalConfig(cfgPath, &kubeadmapiv1alpha3.MasterConfiguration{})
+	}
+	if kubeadmutil.GroupVersionKindsHasNodeConfiguration(gvks) {
+		return NodeConfigFileAndDefaultsToInternalConfig(cfgPath, &kubeadmapiv1alpha3.NodeConfiguration{})
+	}
+	return nil, fmt.Errorf("didn't recognize types with GroupVersionKind: %v", gvks)
+}
+
+// DetectUnsupportedVersion reads YAML bytes, extracts the TypeMeta information and errors out with an user-friendly message if the API spec is too old for this kubeadm version
+func DetectUnsupportedVersion(b []byte) error {
+	gvks, err := kubeadmutil.GroupVersionKindsFromBytes(b)
+	if err != nil {
+		return err
+	}
+
+	// TODO: On our way to making the kubeadm API beta and higher, give good user output in case they use an old config file with a new kubeadm version, and
+	// tell them how to upgrade. The support matrix will look something like this now and in the future:
+	// v1.10 and earlier: v1alpha1
+	// v1.11: v1alpha1 read-only, writes only v1alpha2 config
+	// v1.12: v1alpha2 read-only, writes only v1beta1 config. Warns if the user tries to use v1alpha1
+	// v1.13 and v1.14: v1beta1 read-only, writes only v1 config. Warns if the user tries to use v1alpha1 or v1alpha2.
+	// v1.15: v1 is the only supported format.
+	oldKnownAPIVersions := map[string]string{
+		"kubeadm.k8s.io/v1alpha1": "v1.11",
+	}
+	// If we find an old API version in this gvk list, error out and tell the user why this doesn't work
+	for _, gvk := range gvks {
+		if useKubeadmVersion := oldKnownAPIVersions[gvk.GroupVersion().String()]; len(useKubeadmVersion) != 0 {
+			return fmt.Errorf("your configuration file uses an old API spec: %q. Please use kubeadm %s instead and run 'kubeadm config migrate --old-config old.yaml --new-config new.yaml', which will write the new, similar spec using a newer API version.", gvk.GroupVersion().String(), useKubeadmVersion)
+		}
+	}
+	return nil
+}
+
+// NormalizeKubernetesVersion resolves version labels, sets alternative
+// image registry if requested for CI builds, and validates minimal
+// version that kubeadm SetInitDynamicDefaultssupports.
+func NormalizeKubernetesVersion(cfg *kubeadmapi.MasterConfiguration) error {
+	// Requested version is automatic CI build, thus use KubernetesCI Image Repository for core images
+	if kubeadmutil.KubernetesIsCIVersion(cfg.KubernetesVersion) {
+		cfg.CIImageRepository = constants.DefaultCIImageRepository
+	}
+
+	// Parse and validate the version argument and resolve possible CI version labels
+	ver, err := kubeadmutil.KubernetesReleaseVersion(cfg.KubernetesVersion)
+	if err != nil {
+		return err
+	}
+	cfg.KubernetesVersion = ver
+
+	// Parse the given kubernetes version and make sure it's higher than the lowest supported
+	k8sVersion, err := version.ParseSemantic(cfg.KubernetesVersion)
+	if err != nil {
+		return fmt.Errorf("couldn't parse kubernetes version %q: %v", cfg.KubernetesVersion, err)
+	}
+	if k8sVersion.LessThan(constants.MinimumControlPlaneVersion) {
+		return fmt.Errorf("this version of kubeadm only supports deploying clusters with the control plane version >= %s. Current version: %s", constants.MinimumControlPlaneVersion.String(), cfg.KubernetesVersion)
+	}
+	return nil
+}
+
+// LowercaseSANs can be used to force all SANs to be lowercase so it passes IsDNS1123Subdomain
+func LowercaseSANs(sans []string) {
+	for i, san := range sans {
+		lowercase := strings.ToLower(san)
+		if lowercase != san {
+			glog.V(1).Infof("lowercasing SAN %q to %q", san, lowercase)
+			sans[i] = lowercase
+		}
+	}
+}

cmd/kubeadm/app/util/config/common_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 config
+
+import (
+	"bytes"
+	"testing"
+
+	kubeadmapiv1alpha3 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha3"
+	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
+)
+
+var files = map[string][]byte{
+	"Master_v1alpha1": []byte(`
+apiVersion: kubeadm.k8s.io/v1alpha1
+kind: MasterConfiguration
+`),
+	"Node_v1alpha1": []byte(`
+apiVersion: kubeadm.k8s.io/v1alpha1
+kind: NodeConfiguration
+`),
+	"Master_v1alpha3": []byte(`
+apiVersion: kubeadm.k8s.io/v1alpha3
+kind: MasterConfiguration
+`),
+	"Node_v1alpha3": []byte(`
+apiVersion: kubeadm.k8s.io/v1alpha3
+kind: NodeConfiguration
+`),
+	"NoKind": []byte(`
+apiVersion: baz.k8s.io/v1
+foo: foo
+bar: bar
+`),
+	"NoAPIVersion": []byte(`
+kind: Bar
+foo: foo
+bar: bar
+`),
+}
+
+func TestDetectUnsupportedVersion(t *testing.T) {
+	var tests = []struct {
+		name         string
+		fileContents []byte
+		expectedErr  bool
+	}{
+		{
+			name:         "Master_v1alpha1",
+			fileContents: files["Master_v1alpha1"],
+			expectedErr:  true,
+		},
+		{
+			name:         "Node_v1alpha1",
+			fileContents: files["Node_v1alpha1"],
+			expectedErr:  true,
+		},
+		{
+			name:         "Master_v1alpha3",
+			fileContents: files["Master_v1alpha3"],
+		},
+		{
+			name:         "Node_v1alpha3",
+			fileContents: files["Node_v1alpha3"],
+		},
+		{
+			name:         "DuplicateMaster",
+			fileContents: bytes.Join([][]byte{files["Master_v1alpha3"], files["Master_v1alpha3"]}, []byte(constants.YAMLDocumentSeparator)),
+			expectedErr:  true,
+		},
+		{
+			name:         "NoKind",
+			fileContents: files["NoKind"],
+			expectedErr:  true,
+		},
+		{
+			name:         "NoAPIVersion",
+			fileContents: files["NoAPIVersion"],
+			expectedErr:  true,
+		},
+		{
+			name:         "v1alpha1InMultiple",
+			fileContents: bytes.Join([][]byte{files["Master_v1alpha3"], files["Master_v1alpha1"]}, []byte(constants.YAMLDocumentSeparator)),
+			expectedErr:  true,
+		},
+	}
+
+	for _, rt := range tests {
+		t.Run(rt.name, func(t2 *testing.T) {
+
+			err := DetectUnsupportedVersion(rt.fileContents)
+			if (err != nil) != rt.expectedErr {
+				t2.Errorf("expected error: %t, actual: %t", rt.expectedErr, err != nil)
+			}
+		})
+	}
+}
+
+func TestLowercaseSANs(t *testing.T) {
+	tests := []struct {
+		name string
+		in   []string
+		out  []string
+	}{
+		{
+			name: "empty struct",
+		},
+		{
+			name: "already lowercase",
+			in:   []string{"example.k8s.io"},
+			out:  []string{"example.k8s.io"},
+		},
+		{
+			name: "ip addresses and uppercase",
+			in:   []string{"EXAMPLE.k8s.io", "10.100.0.1"},
+			out:  []string{"example.k8s.io", "10.100.0.1"},
+		},
+		{
+			name: "punycode and uppercase",
+			in:   []string{"xn--7gq663byk9a.xn--fiqz9s", "ANOTHEREXAMPLE.k8s.io"},
+			out:  []string{"xn--7gq663byk9a.xn--fiqz9s", "anotherexample.k8s.io"},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			cfg := &kubeadmapiv1alpha3.MasterConfiguration{
+				APIServerCertSANs: test.in,
+			}
+
+			LowercaseSANs(cfg.APIServerCertSANs)
+
+			if len(cfg.APIServerCertSANs) != len(test.out) {
+				t.Fatalf("expected %d elements, got %d", len(test.out), len(cfg.APIServerCertSANs))
+			}
+
+			for i, expected := range test.out {
+				if cfg.APIServerCertSANs[i] != expected {
+					t.Errorf("expected element %d to be %q, got %q", i, expected, cfg.APIServerCertSANs[i])
+				}
+			}
+		})
+	}
+}

cmd/kubeadm/app/util/config/masterconfig.go

@@ -20,7 +20,6 @@ import (
 	"fmt"
 	"io/ioutil"
 	"net"
-	"strings"
 
 	"github.com/golang/glog"
 
@@ -33,9 +32,7 @@ import (
 	kubeadmapiv1alpha3 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha3"
 	"k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/validation"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
-	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
-	"k8s.io/kubernetes/pkg/util/node"
-	"k8s.io/kubernetes/pkg/util/version"
+	nodeutil "k8s.io/kubernetes/pkg/util/node"
 )
 
 // SetInitDynamicDefaults checks and sets configuration values for the MasterConfiguration object
@@ -88,7 +85,7 @@ func SetInitDynamicDefaults(cfg *kubeadmapi.MasterConfiguration) error {
 		cfg.BootstrapTokens[i].Token = token
 	}
 
-	cfg.NodeRegistration.Name = node.GetHostname(cfg.NodeRegistration.Name)
+	cfg.NodeRegistration.Name = nodeutil.GetHostname(cfg.NodeRegistration.Name)
 
 	// Only if the slice is nil, we should append the master taint. This allows the user to specify an empty slice for no default master taint
 	if cfg.NodeRegistration.Taints == nil {
@@ -152,64 +149,3 @@ func defaultAndValidate(cfg *kubeadmapi.MasterConfiguration) (*kubeadmapi.Master
 	}
 	return cfg, nil
 }
-
-// DetectUnsupportedVersion reads YAML bytes, extracts the TypeMeta information and errors out with an user-friendly message if the API spec is too old for this kubeadm version
-func DetectUnsupportedVersion(b []byte) error {
-	apiVersionStr, _, err := kubeadmutil.ExtractAPIVersionAndKindFromYAML(b)
-	if err != nil {
-		return err
-	}
-
-	// TODO: On our way to making the kubeadm API beta and higher, give good user output in case they use an old config file with a new kubeadm version, and
-	// tell them how to upgrade. The support matrix will look something like this now and in the future:
-	// v1.10 and earlier: v1alpha1
-	// v1.11: v1alpha1 read-only, writes only v1alpha2 config
-	// v1.12: v1alpha2 read-only, writes only v1beta1 config. Warns if the user tries to use v1alpha1
-	// v1.13 and v1.14: v1beta1 read-only, writes only v1 config. Warns if the user tries to use v1alpha1 or v1alpha2.
-	// v1.15: v1 is the only supported format.
-	oldKnownAPIVersions := map[string]string{
-		"kubeadm.k8s.io/v1alpha1": "v1.11",
-	}
-	if useKubeadmVersion := oldKnownAPIVersions[apiVersionStr]; len(useKubeadmVersion) != 0 {
-		return fmt.Errorf("your configuration file seem to use an old API spec. Please use kubeadm %s instead and run 'kubeadm config migrate --old-config old.yaml --new-config new.yaml', which will write the new, similar spec using a newer API version.", useKubeadmVersion)
-	}
-	return nil
-}
-
-// NormalizeKubernetesVersion resolves version labels, sets alternative
-// image registry if requested for CI builds, and validates minimal
-// version that kubeadm supports.
-func NormalizeKubernetesVersion(cfg *kubeadmapi.MasterConfiguration) error {
-	// Requested version is automatic CI build, thus use KubernetesCI Image Repository for core images
-	if kubeadmutil.KubernetesIsCIVersion(cfg.KubernetesVersion) {
-		cfg.CIImageRepository = kubeadmconstants.DefaultCIImageRepository
-	}
-
-	// Parse and validate the version argument and resolve possible CI version labels
-	ver, err := kubeadmutil.KubernetesReleaseVersion(cfg.KubernetesVersion)
-	if err != nil {
-		return err
-	}
-	cfg.KubernetesVersion = ver
-
-	// Parse the given kubernetes version and make sure it's higher than the lowest supported
-	k8sVersion, err := version.ParseSemantic(cfg.KubernetesVersion)
-	if err != nil {
-		return fmt.Errorf("couldn't parse kubernetes version %q: %v", cfg.KubernetesVersion, err)
-	}
-	if k8sVersion.LessThan(kubeadmconstants.MinimumControlPlaneVersion) {
-		return fmt.Errorf("this version of kubeadm only supports deploying clusters with the control plane version >= %s. Current version: %s", kubeadmconstants.MinimumControlPlaneVersion.String(), cfg.KubernetesVersion)
-	}
-	return nil
-}
-
-// LowercaseSANs can be used to force all SANs to be lowercase so it passes IsDNS1123Subdomain
-func LowercaseSANs(sans []string) {
-	for i, san := range sans {
-		lowercase := strings.ToLower(san)
-		if lowercase != san {
-			glog.V(1).Infof("lowercasing SAN %q to %q", san, lowercase)
-			sans[i] = lowercase
-		}
-	}
-}

cmd/kubeadm/app/util/config/masterconfig_test.go

@@ -127,50 +127,3 @@ func TestConfigFileAndDefaultsToInternalConfig(t *testing.T) {
 		})
 	}
 }
-
-func TestLowercaseSANs(t *testing.T) {
-	tests := []struct {
-		name string
-		in   []string
-		out  []string
-	}{
-		{
-			name: "empty struct",
-		},
-		{
-			name: "already lowercase",
-			in:   []string{"example.k8s.io"},
-			out:  []string{"example.k8s.io"},
-		},
-		{
-			name: "ip addresses and uppercase",
-			in:   []string{"EXAMPLE.k8s.io", "10.100.0.1"},
-			out:  []string{"example.k8s.io", "10.100.0.1"},
-		},
-		{
-			name: "punycode and uppercase",
-			in:   []string{"xn--7gq663byk9a.xn--fiqz9s", "ANOTHEREXAMPLE.k8s.io"},
-			out:  []string{"xn--7gq663byk9a.xn--fiqz9s", "anotherexample.k8s.io"},
-		},
-	}
-
-	for _, test := range tests {
-		t.Run(test.name, func(t *testing.T) {
-			cfg := &kubeadmapiv1alpha3.MasterConfiguration{
-				APIServerCertSANs: test.in,
-			}
-
-			LowercaseSANs(cfg.APIServerCertSANs)
-
-			if len(cfg.APIServerCertSANs) != len(test.out) {
-				t.Fatalf("expected %d elements, got %d", len(test.out), len(cfg.APIServerCertSANs))
-			}
-
-			for i, expected := range test.out {
-				if cfg.APIServerCertSANs[i] != expected {
-					t.Errorf("expected element %d to be %q, got %q", i, expected, cfg.APIServerCertSANs[i])
-				}
-			}
-		})
-	}
-}

cmd/kubeadm/app/util/marshal.go

@@ -17,15 +17,20 @@ limitations under the License.
 package util
 
 import (
-	"errors"
+	"bufio"
+	"bytes"
 	"fmt"
+	"io"
 
-	yaml "gopkg.in/yaml.v2"
+	"github.com/ghodss/yaml"
 
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
+	"k8s.io/apimachinery/pkg/util/errors"
+	utilyaml "k8s.io/apimachinery/pkg/util/yaml"
 	clientsetscheme "k8s.io/client-go/kubernetes/scheme"
+	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 )
 
 // MarshalToYaml marshals an object into yaml.
@@ -66,67 +71,88 @@ func UnmarshalFromYamlForCodecs(buffer []byte, gv schema.GroupVersion, codecs se
 	return runtime.Decode(decoder, buffer)
 }
 
-// ExtractAPIVersionAndKindFromYAML extracts the APIVersion and Kind fields from YAML bytes
-func ExtractAPIVersionAndKindFromYAML(b []byte) (string, string, error) {
-	decoded, err := LoadYAML(b)
-	if err != nil {
-		return "", "", fmt.Errorf("unable to decode config from bytes: %v", err)
-	}
+// SplitYAMLDocuments reads the YAML bytes per-document, unmarshals the TypeMeta information from each document
+// and returns a map between the GroupVersionKind of the document and the document bytes
+func SplitYAMLDocuments(yamlBytes []byte) (map[schema.GroupVersionKind][]byte, error) {
+	gvkmap := map[schema.GroupVersionKind][]byte{}
+	knownKinds := map[string]bool{}
+	errs := []error{}
+	buf := bytes.NewBuffer(yamlBytes)
+	reader := utilyaml.NewYAMLReader(bufio.NewReader(buf))
+	for {
+		typeMetaInfo := runtime.TypeMeta{}
+		// Read one YAML document at a time, until io.EOF is returned
+		b, err := reader.Read()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return nil, err
+		}
+		if len(b) == 0 {
+			break
+		}
+		// Deserialize the TypeMeta information of this byte slice
+		if err := yaml.Unmarshal(b, &typeMetaInfo); err != nil {
+			return nil, err
+		}
+		// Require TypeMeta information to be present
+		if len(typeMetaInfo.APIVersion) == 0 || len(typeMetaInfo.Kind) == 0 {
+			errs = append(errs, fmt.Errorf("invalid configuration: kind and apiVersion is mandatory information that needs to be specified in all YAML documents"))
+			continue
+		}
+		// Check whether the kind has been registered before. If it has, throw an error
+		if known := knownKinds[typeMetaInfo.Kind]; known {
+			errs = append(errs, fmt.Errorf("invalid configuration: kind %q is specified twice in YAML file", typeMetaInfo.Kind))
+			continue
+		}
+		knownKinds[typeMetaInfo.Kind] = true
 
-	kindStr, ok := decoded["kind"].(string)
-	if !ok || len(kindStr) == 0 {
-		return "", "", fmt.Errorf("any config file must have the kind field set")
+		// Build a GroupVersionKind object from the deserialized TypeMeta object
+		gv, err := schema.ParseGroupVersion(typeMetaInfo.APIVersion)
+		if err != nil {
+			errs = append(errs, fmt.Errorf("unable to parse apiVersion: %v", err))
+			continue
+		}
+		gvk := gv.WithKind(typeMetaInfo.Kind)
+
+		// Save the mapping between the gvk and the bytes that object consists of
+		gvkmap[gvk] = b
 	}
-	apiVersionStr, ok := decoded["apiVersion"].(string)
-	if !ok || len(apiVersionStr) == 0 {
-		return "", "", fmt.Errorf("any config file must have the apiVersion field set")
+	if err := errors.NewAggregate(errs); err != nil {
+		return nil, err
 	}
-	return apiVersionStr, kindStr, nil
+	return gvkmap, nil
 }
 
-// GroupVersionKindFromBytes parses the bytes and returns the gvk
-// TODO: Find a better way to do this, invoking the API machinery directly without first loading the yaml manually
-func GroupVersionKindFromBytes(b []byte, codecs serializer.CodecFactory) (schema.GroupVersionKind, error) {
-	apiVersionStr, kindStr, err := ExtractAPIVersionAndKindFromYAML(b)
+// GroupVersionKindsFromBytes parses the bytes and returns a gvk slice
+func GroupVersionKindsFromBytes(b []byte) ([]schema.GroupVersionKind, error) {
+	gvkmap, err := SplitYAMLDocuments(b)
 	if err != nil {
-		return schema.EmptyObjectKind.GroupVersionKind(), err
+		return nil, err
 	}
-
-	gv, err := schema.ParseGroupVersion(apiVersionStr)
-	if err != nil {
-		return schema.EmptyObjectKind.GroupVersionKind(), fmt.Errorf("unable to parse apiVersion: %v", err)
+	gvks := []schema.GroupVersionKind{}
+	for gvk := range gvkmap {
+		gvks = append(gvks, gvk)
 	}
-	return gv.WithKind(kindStr), nil
+	return gvks, nil
 }
 
-// LoadYAML is a small wrapper around go-yaml that ensures all nested structs are map[string]interface{} instead of map[interface{}]interface{}.
-func LoadYAML(bytes []byte) (map[string]interface{}, error) {
-	var decoded map[interface{}]interface{}
-	if err := yaml.Unmarshal(bytes, &decoded); err != nil {
-		return map[string]interface{}{}, fmt.Errorf("couldn't unmarshal YAML: %v", err)
-	}
-
-	converted, ok := convert(decoded).(map[string]interface{})
-	if !ok {
-		return map[string]interface{}{}, errors.New("yaml is not a map")
+// GroupVersionKindsHasKind returns whether the following gvk slice contains the kind given as a parameter
+func GroupVersionKindsHasKind(gvks []schema.GroupVersionKind, kind string) bool {
+	for _, gvk := range gvks {
+		if gvk.Kind == kind {
+			return true
+		}
 	}
+	return false
+}
 
-	return converted, nil
+// GroupVersionKindsHasMasterConfiguration returns whether the following gvk slice contains a MasterConfiguration object
+func GroupVersionKindsHasMasterConfiguration(gvks []schema.GroupVersionKind) bool {
+	return GroupVersionKindsHasKind(gvks, constants.MasterConfigurationKind)
 }
 
-// https://stackoverflow.com/questions/40737122/convert-yaml-to-json-without-struct-golang
-func convert(i interface{}) interface{} {
-	switch x := i.(type) {
-	case map[interface{}]interface{}:
-		m2 := map[string]interface{}{}
-		for k, v := range x {
-			m2[k.(string)] = convert(v)
-		}
-		return m2
-	case []interface{}:
-		for i, v := range x {
-			x[i] = convert(v)
-		}
-	}
-	return i
+// GroupVersionKindsHasNodeConfiguration returns whether the following gvk slice contains a NodeConfiguration object
+func GroupVersionKindsHasNodeConfiguration(gvks []schema.GroupVersionKind) bool {
+	return GroupVersionKindsHasKind(gvks, constants.NodeConfigurationKind)
 }

cmd/kubeadm/app/util/marshal_test.go

@@ -17,15 +17,48 @@ limitations under the License.
 package util
 
 import (
+	"bytes"
 	"reflect"
+	"sort"
 	"testing"
 
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/scheme"
 	kubeadmapiv1alpha3 "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha3"
+	"k8s.io/kubernetes/cmd/kubeadm/app/constants"
 )
 
+var files = map[string][]byte{
+	"foo": []byte(`
+kind: Foo
+apiVersion: foo.k8s.io/v1
+fooField: foo
+`),
+	"bar": []byte(`
+apiVersion: bar.k8s.io/v2
+barField: bar
+kind: Bar
+`),
+	"baz": []byte(`
+apiVersion: baz.k8s.io/v1
+kind: Baz
+baz:
+	foo: bar
+`),
+	"nokind": []byte(`
+apiVersion: baz.k8s.io/v1
+foo: foo
+bar: bar
+`),
+	"noapiversion": []byte(`
+kind: Bar
+foo: foo
+bar: bar
+`),
+}
+
 func TestMarshalUnmarshalYaml(t *testing.T) {
 	pod := &corev1.Pod{
 		ObjectMeta: metav1.ObjectMeta{
@@ -114,3 +147,248 @@ func TestMarshalUnmarshalToYamlForCodecs(t *testing.T) {
 		t.Errorf("expected %v, got %v", *cfg, *cfg2)
 	}
 }
+
+func TestSplitYAMLDocuments(t *testing.T) {
+	var tests = []struct {
+		name         string
+		fileContents []byte
+		gvkmap       map[schema.GroupVersionKind][]byte
+		expectedErr  bool
+	}{
+		{
+			name:         "FooOnly",
+			fileContents: files["foo"],
+			gvkmap: map[schema.GroupVersionKind][]byte{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"}: files["foo"],
+			},
+		},
+		{
+			name:         "FooBar",
+			fileContents: bytes.Join([][]byte{files["foo"], files["bar"]}, []byte(constants.YAMLDocumentSeparator)),
+			gvkmap: map[schema.GroupVersionKind][]byte{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"}: files["foo"],
+				{Group: "bar.k8s.io", Version: "v2", Kind: "Bar"}: files["bar"],
+			},
+		},
+		{
+			name:         "FooTwiceInvalid",
+			fileContents: bytes.Join([][]byte{files["foo"], files["bar"], files["foo"]}, []byte(constants.YAMLDocumentSeparator)),
+			expectedErr:  true,
+		},
+		{
+			name:         "InvalidBaz",
+			fileContents: bytes.Join([][]byte{files["foo"], files["baz"]}, []byte(constants.YAMLDocumentSeparator)),
+			expectedErr:  true,
+		},
+		{
+			name:         "InvalidNoKind",
+			fileContents: files["nokind"],
+			expectedErr:  true,
+		},
+		{
+			name:         "InvalidNoAPIVersion",
+			fileContents: files["noapiversion"],
+			expectedErr:  true,
+		},
+	}
+
+	for _, rt := range tests {
+		t.Run(rt.name, func(t2 *testing.T) {
+
+			gvkmap, err := SplitYAMLDocuments(rt.fileContents)
+			if (err != nil) != rt.expectedErr {
+				t2.Errorf("expected error: %t, actual: %t", rt.expectedErr, err != nil)
+			}
+
+			if !reflect.DeepEqual(gvkmap, rt.gvkmap) {
+				t2.Errorf("expected gvkmap: %s\n\tactual: %s\n", rt.gvkmap, gvkmap)
+			}
+		})
+	}
+}
+
+func TestGroupVersionKindsFromBytes(t *testing.T) {
+	var tests = []struct {
+		name         string
+		fileContents []byte
+		gvks         []string
+		expectedErr  bool
+	}{
+		{
+			name:         "FooOnly",
+			fileContents: files["foo"],
+			gvks: []string{
+				"foo.k8s.io/v1, Kind=Foo",
+			},
+		},
+		{
+			name:         "FooBar",
+			fileContents: bytes.Join([][]byte{files["foo"], files["bar"]}, []byte(constants.YAMLDocumentSeparator)),
+			gvks: []string{
+				"foo.k8s.io/v1, Kind=Foo",
+				"bar.k8s.io/v2, Kind=Bar",
+			},
+		},
+		{
+			name:         "FooTwiceInvalid",
+			fileContents: bytes.Join([][]byte{files["foo"], files["bar"], files["foo"]}, []byte(constants.YAMLDocumentSeparator)),
+			gvks:         []string{},
+			expectedErr:  true,
+		},
+		{
+			name:         "InvalidBaz",
+			fileContents: bytes.Join([][]byte{files["foo"], files["baz"]}, []byte(constants.YAMLDocumentSeparator)),
+			gvks:         []string{},
+			expectedErr:  true,
+		},
+		{
+			name:         "InvalidNoKind",
+			fileContents: files["nokind"],
+			gvks:         []string{},
+			expectedErr:  true,
+		},
+		{
+			name:         "InvalidNoAPIVersion",
+			fileContents: files["noapiversion"],
+			gvks:         []string{},
+			expectedErr:  true,
+		},
+	}
+
+	for _, rt := range tests {
+		t.Run(rt.name, func(t2 *testing.T) {
+
+			gvks, err := GroupVersionKindsFromBytes(rt.fileContents)
+			if (err != nil) != rt.expectedErr {
+				t2.Errorf("expected error: %t, actual: %t", rt.expectedErr, err != nil)
+			}
+
+			strgvks := []string{}
+			for _, gvk := range gvks {
+				strgvks = append(strgvks, gvk.String())
+			}
+			sort.Strings(strgvks)
+			sort.Strings(rt.gvks)
+
+			if !reflect.DeepEqual(strgvks, rt.gvks) {
+				t2.Errorf("expected gvks: %s\n\tactual: %s\n", rt.gvks, strgvks)
+			}
+		})
+	}
+}
+
+func TestGroupVersionKindsHasKind(t *testing.T) {
+	var tests = []struct {
+		name     string
+		gvks     []schema.GroupVersionKind
+		kind     string
+		expected bool
+	}{
+		{
+			name: "FooOnly",
+			gvks: []schema.GroupVersionKind{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"},
+			},
+			kind:     "Foo",
+			expected: true,
+		},
+		{
+			name: "FooBar",
+			gvks: []schema.GroupVersionKind{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"},
+				{Group: "bar.k8s.io", Version: "v2", Kind: "Bar"},
+			},
+			kind:     "Bar",
+			expected: true,
+		},
+		{
+			name: "FooBazNoBaz",
+			gvks: []schema.GroupVersionKind{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"},
+				{Group: "bar.k8s.io", Version: "v2", Kind: "Bar"},
+			},
+			kind:     "Baz",
+			expected: false,
+		},
+	}
+
+	for _, rt := range tests {
+		t.Run(rt.name, func(t2 *testing.T) {
+
+			actual := GroupVersionKindsHasKind(rt.gvks, rt.kind)
+			if rt.expected != actual {
+				t2.Errorf("expected gvks has kind: %t\n\tactual: %t\n", rt.expected, actual)
+			}
+		})
+	}
+}
+
+func TestGroupVersionKindsHasMasterConfiguration(t *testing.T) {
+	var tests = []struct {
+		name     string
+		gvks     []schema.GroupVersionKind
+		kind     string
+		expected bool
+	}{
+		{
+			name: "NoMasterConfiguration",
+			gvks: []schema.GroupVersionKind{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"},
+			},
+			expected: false,
+		},
+		{
+			name: "MasterConfigurationFound",
+			gvks: []schema.GroupVersionKind{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"},
+				{Group: "bar.k8s.io", Version: "v2", Kind: "MasterConfiguration"},
+			},
+			expected: true,
+		},
+	}
+
+	for _, rt := range tests {
+		t.Run(rt.name, func(t2 *testing.T) {
+
+			actual := GroupVersionKindsHasMasterConfiguration(rt.gvks)
+			if rt.expected != actual {
+				t2.Errorf("expected gvks has MasterConfiguration: %t\n\tactual: %t\n", rt.expected, actual)
+			}
+		})
+	}
+}
+
+func TestGroupVersionKindsHasNodeConfiguration(t *testing.T) {
+	var tests = []struct {
+		name     string
+		gvks     []schema.GroupVersionKind
+		kind     string
+		expected bool
+	}{
+		{
+			name: "NoNodeConfiguration",
+			gvks: []schema.GroupVersionKind{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"},
+			},
+			expected: false,
+		},
+		{
+			name: "NodeConfigurationFound",
+			gvks: []schema.GroupVersionKind{
+				{Group: "foo.k8s.io", Version: "v1", Kind: "Foo"},
+				{Group: "bar.k8s.io", Version: "v2", Kind: "NodeConfiguration"},
+			},
+			expected: true,
+		},
+	}
+
+	for _, rt := range tests {
+		t.Run(rt.name, func(t2 *testing.T) {
+
+			actual := GroupVersionKindsHasNodeConfiguration(rt.gvks)
+			if rt.expected != actual {
+				t2.Errorf("expected gvks has NodeConfiguration: %t\n\tactual: %t\n", rt.expected, actual)
+			}
+		})
+	}
+}