Create cluster-id file on MicroShift startup

pkg/cmd/run.go

@@ -212,6 +212,7 @@ func RunMicroshift(cfg *config.Config) error {
 	util.Must(m.AddService(node.NewKubeletServer(cfg)))
 	util.Must(m.AddService(loadbalancerservice.NewLoadbalancerServiceController(cfg)))
 	util.Must(m.AddService(controllers.NewKubeStorageVersionMigrator(cfg)))
+	util.Must(m.AddService(controllers.NewClusterID(cfg)))
 
 	// Storing and clearing the env, so other components don't send the READY=1 until MicroShift is fully ready
 	notifySocket := os.Getenv("NOTIFY_SOCKET")

pkg/controllers/clusterid.go

@@ -0,0 +1,88 @@
+/*
+Copyright © 2024 MicroShift Contributors
+
+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 controllers
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+
+	"github.com/openshift/microshift/pkg/config"
+
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	coreclientv1 "k8s.io/client-go/kubernetes/typed/core/v1"
+	"k8s.io/client-go/rest"
+	"k8s.io/client-go/tools/clientcmd"
+	"k8s.io/klog/v2"
+)
+
+type ClusterID struct {
+	cfg *config.Config
+}
+
+func NewClusterID(cfg *config.Config) *ClusterID {
+	s := &ClusterID{}
+	s.cfg = cfg
+	return s
+}
+
+func (s *ClusterID) Name() string { return "cluster-id-manager" }
+func (s *ClusterID) Dependencies() []string {
+	return []string{"kube-apiserver"}
+}
+
+func (s *ClusterID) Run(ctx context.Context, ready chan<- struct{}, stopped chan<- struct{}) error {
+	defer close(stopped)
+	defer close(ready)
+
+	// Read the 'kube-system' namespace attributes
+	restConfig, err := clientcmd.BuildConfigFromFlags("", s.cfg.KubeConfigPath(config.KubeAdmin))
+	if err != nil {
+		panic(err)
+	}
+	coreClient := coreclientv1.NewForConfigOrDie(rest.AddUserAgent(restConfig, "core-agent"))
+	namespace, err := coreClient.Namespaces().Get(ctx, "kube-system", metav1.GetOptions{})
+	if err != nil {
+		panic(err)
+	}
+
+	// Use the 'kube-system' namespace metadata UID as the MicroShift Cluster ID
+	clusterID := string(namespace.ObjectMeta.UID)
+	// Write <config.DataDir>/cluster-id file if it does not already exist
+	initClusterIDFile(clusterID)
+	// Log the cluster ID
+	klog.Infof("MicroShift Cluster ID: %v", clusterID)
+
+	return ctx.Err()
+}
+
+func initClusterIDFile(clusterID string) {
+	// The location of the cluster ID file
+	fileName := filepath.Join(config.DataDir, "cluster-id")
+
+	// Do not create the cluster ID file if it already exists
+	_, err := os.Stat(fileName)
+	if !os.IsNotExist(err) {
+		return
+	}
+
+	// Write the cluster ID to a new file
+	klog.Infof("Writing MicroShift Cluster ID '%v' to '%v'", clusterID, fileName)
+	err = os.WriteFile(fileName, []byte(clusterID), 0400)
+	if err != nil {
+		panic(err)
+	}
+}