OKD-294: Migrate runtime from runc to crun on an upgrade for OKD

pkg/controller/container-runtime-config/container_runtime_config_controller.go

@@ -60,7 +60,9 @@ const (
 	// 5ms, 10ms, 20ms, 40ms, 80ms, 160ms, 320ms, 640ms, 1.3s, 2.6s, 5.1s, 10.2s, 20.4s, 41s, 82s
 	maxRetries = 15
 
-	builtInLabelKey = "machineconfiguration.openshift.io/mco-built-in"
+	builtInLabelKey    = "machineconfiguration.openshift.io/mco-built-in"
+	configMapName      = "crio-default-container-runtime"
+	forceSyncOnUpgrade = "force-sync-on-upgrade"
 )
 
 var (
@@ -79,6 +81,7 @@ type Controller struct {
 	templatesDir string
 
 	client        mcfgclientset.Interface
+	kubeClient    clientset.Interface
 	configClient  configclientset.Interface
 	eventRecorder record.EventRecorder
 
@@ -148,6 +151,7 @@ func New(
 	ctrl := &Controller{
 		templatesDir:  templatesDir,
 		client:        mcfgClient,
+		kubeClient:    kubeClient,
 		configClient:  configClient,
 		eventRecorder: ctrlcommon.NamespacedEventRecorder(eventBroadcaster.NewRecorder(scheme.Scheme, corev1.EventSource{Component: "machineconfigcontroller-containerruntimeconfigcontroller"})),
 		queue: workqueue.NewTypedRateLimitingQueueWithConfig(
@@ -213,6 +217,7 @@ func New(
 
 	ctrl.clusterVersionLister = clusterVersionInformer.Lister()
 	ctrl.clusterVersionListerSynced = clusterVersionInformer.Informer().HasSynced
+	ctrl.queue.Add(forceSyncOnUpgrade)
 
 	ctrl.fgHandler = fgHandler
 
@@ -596,6 +601,60 @@ func (ctrl *Controller) addAnnotation(cfg *mcfgv1.ContainerRuntimeConfig, annota
 	return annotationUpdateErr
 }
 
+// migrateRuncToCrun performs the upgrade migration from runc to crun as the default container runtime.
+// This function checks for the existence of the crio-default-container-runtime ConfigMap. If it exists,
+// it deletes the MachineConfigs for master and worker pools, then deletes the ConfigMap to prevent
+// re-running the migration.
+func (ctrl *Controller) migrateRuncToCrun() error {
+	// Check if the migration ConfigMap exists
+	_, err := ctrl.kubeClient.CoreV1().ConfigMaps(ctrlcommon.MCONamespace).Get(context.TODO(), configMapName, metav1.GetOptions{})
+	if errors.IsNotFound(err) {
+		// ConfigMap doesn't exist, no migration needed
+		return nil
+	}
+	if err != nil {
+		return fmt.Errorf("error checking for crio-default-container-runtime configmap: %w", err)
+	}
+
+	klog.Info("Found crio-default-container-runtime ConfigMap, starting migration from runc to crun")
+
+	// Get all MachineConfigPools
+	pools, err := ctrl.mcpLister.List(labels.Everything())
+	if err != nil {
+		return fmt.Errorf("error listing MachineConfigPools: %w", err)
+	}
+
+	// Only process master and worker pools for the migration
+	for _, pool := range pools {
+		if pool.Name != ctrlcommon.MachineConfigPoolMaster && pool.Name != ctrlcommon.MachineConfigPoolWorker {
+			continue
+		}
+
+		// Get the MachineConfig name for this pool
+		mcName := fmt.Sprintf("00-override-%s-generated-crio-default-container-runtime", pool.Name)
+
+		// Delete the existing MachineConfig
+		err := ctrl.client.MachineconfigurationV1().MachineConfigs().Delete(context.TODO(), mcName, metav1.DeleteOptions{})
+		if errors.IsNotFound(err) {
+			klog.Infof("MachineConfig %s not found, skipping migration for pool %s", mcName, pool.Name)
+			continue
+		}
+		if err != nil {
+			return fmt.Errorf("error deleting MachineConfig %s: %w", mcName, err)
+		}
+
+		klog.Infof("Successfully deleted MachineConfig %s", mcName)
+	}
+
+	// Delete the ConfigMap after successful migration
+	if err := ctrl.kubeClient.CoreV1().ConfigMaps(ctrlcommon.MCONamespace).Delete(context.TODO(), configMapName, metav1.DeleteOptions{}); err != nil && !errors.IsNotFound(err) {
+		return fmt.Errorf("error deleting crio-default-container-runtime configmap: %w", err)
+	}
+
+	klog.Info("Successfully completed migration from runc to crun and deleted migration ConfigMap")
+	return nil
+}
+
 // syncContainerRuntimeConfig will sync the ContainerRuntimeconfig with the given key.
 // This function is not meant to be invoked concurrently with the same key.
 // nolint: gocyclo
@@ -606,6 +665,17 @@ func (ctrl *Controller) syncContainerRuntimeConfig(key string) error {
 		klog.V(4).Infof("Finished syncing ContainerRuntimeconfig %q (%v)", key, time.Since(startTime))
 	}()
 
+	// OKD only: Run the migration function at the start of sync
+	if version.IsSCOS() {
+		if err := ctrl.migrateRuncToCrun(); err != nil {
+			return fmt.Errorf("Error during runc to crun migration: %w", err)
+		}
+	}
+
+	if key == forceSyncOnUpgrade {
+		return nil
+	}
+
 	_, name, err := cache.SplitMetaNamespaceKey(key)
 	if err != nil {
 		return err