Create command for rotating cluster CA

cmd/kops/root.go

@@ -149,6 +149,7 @@ func NewCmdRoot(f *util.Factory, out io.Writer) *cobra.Command {
 	cmd.AddCommand(NewCmdReplace(f, out))
 	cmd.AddCommand(NewCmdRollingUpdate(f, out))
 	cmd.AddCommand(NewCmdSet(f, out))
+	cmd.AddCommand(NewCmdRotate(f, out))
 	cmd.AddCommand(NewCmdToolbox(f, out))
 	cmd.AddCommand(NewCmdValidate(f, out))
 	cmd.AddCommand(NewCmdVersion(f, out))

cmd/kops/rotate.go

@@ -0,0 +1,51 @@
+/*
+Copyright 2021 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 main
+
+import (
+	"io"
+
+	"github.com/spf13/cobra"
+	"k8s.io/kops/cmd/kops/util"
+	"k8s.io/kubectl/pkg/util/i18n"
+	"k8s.io/kubectl/pkg/util/templates"
+)
+
+var (
+	rotateLong = templates.LongDesc(i18n.T(`
+	rotates secrets.`))
+
+	rotateExample = templates.Examples(i18n.T(`
+	# Rotate the cluster CA
+	kops rotate ca --name k8s-cluster.example.com
+	`))
+
+	rotateShort = i18n.T(`Rotates secrets.`)
+)
+
+func NewCmdRotate(f *util.Factory, out io.Writer) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:     "rotate",
+		Short:   rotateShort,
+		Long:    rotateLong,
+		Example: rotateExample,
+	}
+
+	cmd.AddCommand(NewCmdRotateCA(f, out))
+
+	return cmd
+}

cmd/kops/rotate_ca.go

@@ -0,0 +1,310 @@
+/*
+Copyright 2021 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 main
+
+import (
+	"bufio"
+	"context"
+	"crypto/x509/pkix"
+	"encoding/base64"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/spf13/cobra"
+	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/klog/v2"
+	"k8s.io/kops/cmd/kops/util"
+	"k8s.io/kops/pkg/apis/kops"
+	"k8s.io/kops/pkg/apis/kops/model"
+	"k8s.io/kops/pkg/pki"
+	"k8s.io/kops/upup/pkg/fi"
+	"k8s.io/kubectl/pkg/util/i18n"
+	"k8s.io/kubectl/pkg/util/templates"
+)
+
+var (
+	rotateCALong = templates.LongDesc(i18n.T(`
+	rotates the cluster CA.`))
+
+	rotateCAExample = templates.Examples(i18n.T(`
+	# Rotate the cluster CA
+	kops rotate ca --name k8s-cluster.example.com
+	`))
+
+	rotateCAShort = i18n.T(`Rotates the cluster CA.`)
+)
+
+func NewCmdRotateCA(f *util.Factory, out io.Writer) *cobra.Command {
+
+	cmd := &cobra.Command{
+		Use:     "ca",
+		Long:    rotateCALong,
+		Short:   rotateCAShort,
+		Example: rotateCAExample,
+		Run: func(cmd *cobra.Command, args []string) {
+			ctx := context.Background()
+
+			err := rootCommand.ProcessArgs(args)
+			if err != nil {
+				exitWithError(err)
+			}
+
+			clusterName := rootCommand.ClusterName()
+
+			if err := RunRotateCA(ctx, f, clusterName, out); err != nil {
+				exitWithError(err)
+			}
+		},
+	}
+
+	return cmd
+}
+
+func RunRotateCA(ctx context.Context, f *util.Factory, clusterName string, out io.Writer) error {
+
+	cluster, err := rootCommand.Cluster(ctx)
+	if err != nil {
+		return err
+	}
+
+	scanner := bufio.NewScanner(os.Stdin)
+
+	contextName := cluster.ObjectMeta.Name
+	clientConfig, err := clientcmd.NewDefaultClientConfigLoadingRules().Load()
+
+	if err != nil {
+		return fmt.Errorf("failed to delete secondary key: %w", err)
+	}
+
+	if !model.UseKopsControllerForNodeBootstrap(cluster) {
+		return fmt.Errorf("only clusters using kops-controller for boostrapping nodes are supported")
+	}
+
+	exportAdmin := clientConfig.Contexts[contextName].AuthInfo == contextName
+
+	fmt.Println("This comamnd will rotate the cluster CA. It is largely safe, but be aware of the following:")
+	fmt.Println(" * exporting the admin TLS credentials before this command has succeeded will break")
+	fmt.Println("   your client credentials and the only way to recover is to `kops rolling update --cloudonly --yes --force`")
+	fmt.Println(" * This command will rotate all nodes multiple times. This will take a while.")
+	fmt.Println(" * It is safe to restart this command provided you did not export credentials manually")
+	fmt.Println("")
+	fmt.Println("Your cluster should be fully updated and rotated before starting this procedure.")
+	fmt.Println("")
+	if exportAdmin {
+		fmt.Println("The admin TLS credentials was detected. We will export the admin credentials after rotating the CA")
+	} else {
+		fmt.Println("Could not detect any admin credentials. Assuming admin credentials are not in use.")
+	}
+
+	fmt.Println("If you understand the above, type 'yes'. Anything else will abort.")
+	scanner.Scan()
+	err = scanner.Err()
+	if err != nil {
+		exitWithError(fmt.Errorf("unable to interpret input: %w", err))
+	}
+	val := scanner.Text()
+	val = strings.TrimSpace(val)
+	val = strings.ToLower(val)
+	if val != "yes" {
+		exitWithError(fmt.Errorf("Aborting"))
+	}
+
+	clientset, err := f.Clientset()
+	if err != nil {
+		return err
+	}
+
+	keyStore, err := clientset.KeyStore(cluster)
+	if err != nil {
+		return err
+	}
+
+	pool, err := keyStore.FindCertificatePool(fi.CertificateIDCA)
+	if err != nil {
+		return fmt.Errorf("could not fetch the CA pool: %w", err)
+	}
+
+	if len(pool.Secondary) > 0 {
+		klog.Info("Secondary CA cert already in the pool. Not issuing a new CA")
+	} else {
+		err := rotateCAIssueCert(keyStore)
+		if err != nil {
+			return fmt.Errorf("could not issue new CA: %w", err)
+		}
+
+		//Update the pool
+		pool, err = keyStore.FindCertificatePool(fi.CertificateIDCA)
+		if err != nil {
+			return fmt.Errorf("could not fetch the CA pool: %w", err)
+		}
+	}
+
+	// Update the cluster to trust both CAs
+	err = rotateCAUpdateCluster(ctx, cluster, pool, f, out, false)
+	if err != nil {
+		return fmt.Errorf("failed to update the cluster: %w", err)
+	}
+
+	//Delete the old key
+	klog.Info("deleting the old CA")
+
+	keyId := pool.Secondary[0].Certificate.SerialNumber.String()
+	keyset, err := keyStore.FindCertificateKeyset(fi.CertificateIDCA)
+	if err != nil {
+		return fmt.Errorf("failed to load keyset: %w", err)
+	}
+
+	err = keyStore.DeleteKeysetItem(keyset, keyId)
+	if err != nil {
+		return fmt.Errorf("failed to delete secondary key: %w", err)
+	}
+
+	if exportAdmin {
+		klog.Info("Detected the admin TLS user. Will also export a new admin certificate")
+	} else {
+		klog.Info("Could not detect the admin TLS user. Assuming existing credentials will continue to work")
+	}
+
+	// Update the cluster one last time to trust only the new CA
+	err = rotateCAUpdateCluster(ctx, cluster, pool, f, out, exportAdmin)
+	if err != nil {
+		return fmt.Errorf("failed to update the cluster: %w", err)
+	}
+
+	return nil
+}
+
+func rotateCAIssueCert(keyStore fi.CAStore) error {
+
+	klog.Infof("Issuing new certificate")
+
+	serial := pki.BuildPKISerial(time.Now().UnixNano())
+
+	subjectPkix := &pkix.Name{
+		CommonName: "kubernetes",
+	}
+
+	req := pki.IssueCertRequest{
+		Signer:         fi.CertificateIDCA,
+		Type:           "ca",
+		Subject:        *subjectPkix,
+		AlternateNames: []string{},
+		Serial:         serial,
+	}
+	cert, privateKey, _, err := pki.IssueCert(&req, keyStore)
+	if err != nil {
+		return err
+	}
+	err = keyStore.StoreKeypair(fi.CertificateIDCA, cert, privateKey)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func rotateCAUpdateServiceAccounts(ctx context.Context, cluster *kops.Cluster, caBundle []byte) error {
+	klog.Info("updating ServiceAccounts with a new CA bundle")
+
+	caBundle64 := base64.StdEncoding.EncodeToString(caBundle)
+	caBundle64Bytes := []byte(caBundle64)
+
+	contextName := cluster.ObjectMeta.Name
+	configLoadingRules := clientcmd.NewDefaultClientConfigLoadingRules()
+	config, err := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(
+		configLoadingRules,
+		&clientcmd.ConfigOverrides{CurrentContext: contextName}).ClientConfig()
+	if err != nil {
+		return fmt.Errorf("cannot load kubecfg settings for %q: %v", contextName, err)
+	}
+
+	k8sClient, err := kubernetes.NewForConfig(config)
+
+	if err != nil {
+		return fmt.Errorf("cannot build kubernetes api client for %q: %v", contextName, err)
+	}
+
+	secretClient := k8sClient.CoreV1().Secrets("")
+
+	secrets, err := secretClient.List(ctx, v1.ListOptions{
+		FieldSelector: "type=kubernetes.io/service-account-token",
+	})
+	if err != nil {
+		return err
+	}
+
+	for _, secret := range secrets.Items {
+		secret.Data["ca.crt"] = caBundle64Bytes
+		secretClient.Update(ctx, &secret, v1.UpdateOptions{})
+	}
+
+	return nil
+}
+
+func rotateCAUpdateCluster(ctx context.Context, cluster *kops.Cluster, pool *fi.CertificatePool, f *util.Factory, out io.Writer, exportAdmin bool) error {
+	caBundle, err := pool.AsBytes()
+	if err != nil {
+		return fmt.Errorf("failed to encode ca bundle: %w", err)
+	}
+
+	//Update service accounts to trust old and new CA
+	err = rotateCAUpdateServiceAccounts(ctx, cluster, caBundle)
+	if err != nil {
+		return fmt.Errorf("error updating ServiceAccounts: %v", err)
+	}
+
+	adminTTL, _ := time.ParseDuration("0")
+	if exportAdmin {
+		adminTTL, _ = time.ParseDuration("18h")
+	}
+
+	//New kubeconfig with bundled CA so we trust both new and old api servers
+	RunExportKubecfg(ctx, f, out, &ExportKubecfgOptions{admin: adminTTL}, []string{})
+
+	klog.Info("rotating all nodes")
+
+	//Update nodes first. This will make kubelet trust new and old CA.
+	ruo := &RollingUpdateOptions{}
+	ruo.InitDefaults()
+	ruo.Yes = true
+	ruo.ClusterName = cluster.ObjectMeta.Name
+	ruo.Force = true
+	ruo.InstanceGroupRoles = []string{"node"}
+
+	err = RunRollingUpdateCluster(ctx, f, out, ruo)
+	if err != nil {
+		return fmt.Errorf("failed to rotate cluster: %v", err)
+	}
+
+	klog.Info("rotating the control plane")
+
+	//Update masters. This will issue new certs for k8s using the new CA.
+	//New nodes, service accounts etc will use new CA
+	ruo.InstanceGroupRoles = []string{"master", "apiserver"}
+
+	err = RunRollingUpdateCluster(ctx, f, out, ruo)
+	if err != nil {
+		return fmt.Errorf("failed to rotate cluster: %v", err)
+	}
+	return nil
+
+}