kubeadm: Upload configuration used at 'kubeadm init' time to ConfigMap for easier upgrades

cmd/kubeadm/app/cmd/init.go

@@ -41,6 +41,7 @@ import (
 	markmasterphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/markmaster"
 	selfhostingphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/selfhosting"
 	tokenphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/token"
+	uploadconfigphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/uploadconfig"
 	"k8s.io/kubernetes/cmd/kubeadm/app/preflight"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
 	configutil "k8s.io/kubernetes/cmd/kubeadm/app/util/config"
@@ -266,6 +267,11 @@ func (i *Init) Run(out io.Writer) error {
 
 	// PHASE 5: Install and deploy all addons, and configure things as necessary
 
+	// Upload currently used configuration to the cluster
+	if err := uploadconfigphase.UploadConfiguration(i.cfg, client); err != nil {
+		return err
+	}
+
 	// Create the necessary ServiceAccounts
 	if err := apiconfigphase.CreateServiceAccounts(client); err != nil {
 		return err

cmd/kubeadm/app/cmd/phases/certs.go

@@ -25,7 +25,6 @@ import (
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmapiext "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
-	"k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/validation"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	certphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/certs"
 	"k8s.io/kubernetes/cmd/kubeadm/app/phases/certs/pkiutil"
@@ -132,24 +131,9 @@ func runCmdFunc(cmdFunc func(cfg *kubeadmapi.MasterConfiguration) error, cfgPath
 	// are shared between sub commands and gets access to current value e.g. flags value.
 
 	return func(cmd *cobra.Command, args []string) {
-		internalcfg := &kubeadmapi.MasterConfiguration{}
 
-		// Takes passed flags into account; the defaulting is executed once again enforcing assignement of
+		// This call returns the ready-to-use configuration based on the configuration file that might or might not exist and the default cfg populated by flags
-		// static default values to cfg only for values not provided with flags
+		internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(*cfgPath, cfg)
-		api.Scheme.Default(cfg)
-		api.Scheme.Convert(cfg, internalcfg, nil)
-
-		// Loads configuration from config file, if provided
-		// Nb. --config overrides command line flags
-		err := configutil.TryLoadMasterConfiguration(*cfgPath, internalcfg)
-		kubeadmutil.CheckErr(err)
-
-		// Applies dynamic defaults to settings not provided with flags
-		err = configutil.SetInitDynamicDefaults(internalcfg)
-		kubeadmutil.CheckErr(err)
-
-		// Validates cfg (flags/configs + defaults + dynamic defaults)
-		err = validation.ValidateMasterConfiguration(internalcfg).ToAggregate()
 		kubeadmutil.CheckErr(err)
 
 		// Execute the cmdFunc

cmd/kubeadm/app/cmd/phases/kubeconfig.go

@@ -24,7 +24,6 @@ import (
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 	kubeadmapiext "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
-	"k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/validation"
 	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
 	kubeconfigphase "k8s.io/kubernetes/cmd/kubeadm/app/phases/kubeconfig"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
@@ -141,24 +140,9 @@ func runCmdFuncKubeConfig(cmdFunc func(outDir string, cfg *kubeadmapi.MasterConf
 	// are shared between sub commands and gets access to current value e.g. flags value.
 
 	return func(cmd *cobra.Command, args []string) {
-		internalcfg := &kubeadmapi.MasterConfiguration{}
 
-		// Takes passed flags into account; the defaulting is executed once again enforcing assignement of
+		// This call returns the ready-to-use configuration based on the configuration file that might or might not exist and the default cfg populated by flags
-		// static default values to cfg only for values not provided with flags
+		internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(*cfgPath, cfg)
-		api.Scheme.Default(cfg)
-		api.Scheme.Convert(cfg, internalcfg, nil)
-
-		// Loads configuration from config file, if provided
-		// Nb. --config overrides command line flags
-		err := configutil.TryLoadMasterConfiguration(*cfgPath, internalcfg)
-		kubeadmutil.CheckErr(err)
-
-		// Applies dynamic defaults to settings not provided with flags
-		err = configutil.SetInitDynamicDefaults(internalcfg)
-		kubeadmutil.CheckErr(err)
-
-		// Validates cfg (flags/configs + defaults + dynamic defaults)
-		err = validation.ValidateMasterConfiguration(internalcfg).ToAggregate()
 		kubeadmutil.CheckErr(err)
 
 		// Execute the cmdFunc

cmd/kubeadm/app/cmd/phases/phase.go

@@ -35,6 +35,7 @@ func NewCmdPhase(out io.Writer) *cobra.Command {
 	cmd.AddCommand(NewCmdPreFlight())
 	cmd.AddCommand(NewCmdSelfhosting())
 	cmd.AddCommand(NewCmdMarkMaster())
+	cmd.AddCommand(NewCmdUploadConfig())
 
 	return cmd
 }

cmd/kubeadm/app/cmd/phases/uploadconfig.go

@@ -0,0 +1,58 @@
+/*
+Copyright 2017 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 phases
+
+import (
+	"fmt"
+
+	"github.com/spf13/cobra"
+
+	kubeadmapiext "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
+	"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"
+	kubeconfigutil "k8s.io/kubernetes/cmd/kubeadm/app/util/kubeconfig"
+)
+
+// NewCmdUploadConfig returns the Cobra command for running the uploadconfig phase
+func NewCmdUploadConfig() *cobra.Command {
+	var cfgPath, kubeConfigFile string
+	cmd := &cobra.Command{
+		Use:     "upload-config",
+		Short:   "Upload the currently used configuration for kubeadm to a ConfigMap in the cluster for future use in reconfiguration and upgrades of the cluster.",
+		Aliases: []string{"uploadconfig"},
+		Run: func(_ *cobra.Command, args []string) {
+			if len(cfgPath) == 0 {
+				kubeadmutil.CheckErr(fmt.Errorf("The --config flag is mandatory"))
+			}
+			client, err := kubeconfigutil.ClientSetFromFile(kubeConfigFile)
+			kubeadmutil.CheckErr(err)
+
+			defaultcfg := &kubeadmapiext.MasterConfiguration{}
+			internalcfg, err := configutil.ConfigFileAndDefaultsToInternalConfig(cfgPath, defaultcfg)
+			kubeadmutil.CheckErr(err)
+
+			err = uploadconfig.UploadConfiguration(internalcfg, client)
+			kubeadmutil.CheckErr(err)
+		},
+	}
+
+	cmd.Flags().StringVar(&kubeConfigFile, "kubeconfig", "/etc/kubernetes/admin.conf", "The KubeConfig file to use for talking to the cluster")
+	cmd.Flags().StringVar(&cfgPath, "config", "", "Path to kubeadm config file (WARNING: Usage of a configuration file is experimental)")
+
+	return cmd
+}

cmd/kubeadm/app/constants/constants.go

@@ -96,6 +96,12 @@ const (
 	// It's copied over to kubeadm until it's merged in core: https://github.com/kubernetes/kubernetes/pull/39112
 	LabelNodeRoleMaster = "node-role.kubernetes.io/master"
 
+	// MasterConfigurationConfigMap specifies in what ConfigMap in the kube-system namespace the `kubeadm init` configuration should be stored
+	MasterConfigurationConfigMap = "kubeadm-config"
+
+	// MasterConfigurationConfigMapKey specifies in what ConfigMap key the master configuration should be stored
+	MasterConfigurationConfigMapKey = "MasterConfiguration"
+
 	// MinExternalEtcdVersion indicates minimum external etcd version which kubeadm supports
 	MinExternalEtcdVersion = "3.0.14"
 

cmd/kubeadm/app/phases/uploadconfig/BUILD

@@ -0,0 +1,38 @@
+package(default_visibility = ["//visibility:public"])
+
+licenses(["notice"])
+
+load(
+    "@io_bazel_rules_go//go:def.bzl",
+    "go_library",
+)
+
+go_library(
+    name = "go_default_library",
+    srcs = ["saveconfig.go"],
+    tags = ["automanaged"],
+    deps = [
+        "//cmd/kubeadm/app/apis/kubeadm:go_default_library",
+        "//cmd/kubeadm/app/apis/kubeadm/v1alpha1:go_default_library",
+        "//cmd/kubeadm/app/constants:go_default_library",
+        "//pkg/api:go_default_library",
+        "//vendor/github.com/ghodss/yaml:go_default_library",
+        "//vendor/k8s.io/api/core/v1:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/api/errors:go_default_library",
+        "//vendor/k8s.io/apimachinery/pkg/apis/meta/v1:go_default_library",
+        "//vendor/k8s.io/client-go/kubernetes:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [":package-srcs"],
+    tags = ["automanaged"],
+)

cmd/kubeadm/app/phases/uploadconfig/uploadconfig.go

@@ -0,0 +1,67 @@
+/*
+Copyright 2017 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 uploadconfig
+
+import (
+	"fmt"
+
+	"github.com/ghodss/yaml"
+
+	"k8s.io/api/core/v1"
+	apierrs "k8s.io/apimachinery/pkg/api/errors"
+	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"
+	kubeadmconstants "k8s.io/kubernetes/cmd/kubeadm/app/constants"
+	"k8s.io/kubernetes/pkg/api"
+)
+
+// UploadConfiguration saves the MasterConfiguration used for later reference (when upgrading for instance)
+func UploadConfiguration(cfg *kubeadmapi.MasterConfiguration, client clientset.Interface) error {
+
+	fmt.Printf("[uploadconfig] Storing the configuration used in ConfigMap %q in the %q Namespace\n", kubeadmconstants.MasterConfigurationConfigMap, metav1.NamespaceSystem)
+
+	// Convert cfg to the external version as that's the only version of the API that can be deserialized later
+	externalcfg := &kubeadmapiext.MasterConfiguration{}
+	api.Scheme.Convert(cfg, externalcfg, nil)
+
+	cfgYaml, err := yaml.Marshal(*externalcfg)
+	if err != nil {
+		return err
+	}
+
+	cm := &v1.ConfigMap{
+		ObjectMeta: metav1.ObjectMeta{
+			Name:      kubeadmconstants.MasterConfigurationConfigMap,
+			Namespace: metav1.NamespaceSystem,
+		},
+		Data: map[string]string{
+			kubeadmconstants.MasterConfigurationConfigMapKey: string(cfgYaml),
+		},
+	}
+
+	if _, err := client.CoreV1().ConfigMaps(cm.ObjectMeta.Namespace).Create(cm); err != nil {
+		if !apierrs.IsAlreadyExists(err) {
+			return err
+		}
+		if _, err := client.CoreV1().ConfigMaps(cm.ObjectMeta.Namespace).Update(cm); err != nil {
+			return err
+		}
+	}
+	return nil
+}

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

@@ -24,6 +24,8 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	netutil "k8s.io/apimachinery/pkg/util/net"
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
+	kubeadmapiext "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm/v1alpha1"
+	"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"
 	tokenutil "k8s.io/kubernetes/cmd/kubeadm/app/util/token"
@@ -72,7 +74,7 @@ func SetInitDynamicDefaults(cfg *kubeadmapi.MasterConfiguration) error {
 }
 
 // TryLoadMasterConfiguration tries to loads a Master configuration from the given file (if defined)
-func TryLoadMasterConfiguration(cfgPath string, cfg *kubeadmapi.MasterConfiguration) error {
+func TryLoadMasterConfiguration(cfgPath string, cfg *kubeadmapiext.MasterConfiguration) error {
 
 	if cfgPath != "" {
 		b, err := ioutil.ReadFile(cfgPath)
@@ -86,3 +88,34 @@ func TryLoadMasterConfiguration(cfgPath string, cfg *kubeadmapi.MasterConfigurat
 
 	return nil
 }
+
+// ConfigFileAndDefaultsToInternalConfig takes a path to a config file and a versioned configuration that can serve as the default config
+// If cfgPath is specified, defaultversionedcfg will always get overridden. Otherwise, the default config (often populated by flags) will be used.
+// Then the external, versioned configuration is defaulted and converted to the internal type.
+// Right thereafter, the configuration is defaulted again with dynamic values (like IP addresses of a machine, etc)
+// Lastly, the internal config is validated and returned.
+func ConfigFileAndDefaultsToInternalConfig(cfgPath string, defaultversionedcfg *kubeadmapiext.MasterConfiguration) (*kubeadmapi.MasterConfiguration, error) {
+	internalcfg := &kubeadmapi.MasterConfiguration{}
+
+	// Loads configuration from config file, if provided
+	// Nb. --config overrides command line flags
+	if err := TryLoadMasterConfiguration(cfgPath, defaultversionedcfg); err != nil {
+		return nil, err
+	}
+
+	// Takes passed flags into account; the defaulting is executed once again enforcing assignement of
+	// static default values to cfg only for values not provided with flags
+	api.Scheme.Default(defaultversionedcfg)
+	api.Scheme.Convert(defaultversionedcfg, internalcfg, nil)
+
+	// Applies dynamic defaults to settings not provided with flags
+	if err := SetInitDynamicDefaults(internalcfg); err != nil {
+		return nil, err
+	}
+
+	// Validates cfg (flags/configs + defaults + dynamic defaults)
+	if err := validation.ValidateMasterConfiguration(internalcfg).ToAggregate(); err != nil {
+		return nil, err
+	}
+	return internalcfg, nil
+}