feat: stall nomos migrate if HNC is enabled (#1454)

This requires for the user to disable HNC before removing Config
Management, so that ACM helps with the uninstallation of HNC before it
is absent from the cluster. This is intended to streamline the
experience of migrating to OSS HNC.

cmd/nomos/migrate/configmanagement.go

@@ -40,6 +40,11 @@ func migrateConfigManagement(ctx context.Context, cc *status.ClusterClient, kube
 		printNotice("The cluster is already running as an OSS installation.")
 		return nil
 	}
+	if isHNCEnabled, err := cc.ConfigManagement.IsHNCEnabled(ctx); err != nil {
+		return err
+	} else if isHNCEnabled {
+		return fmt.Errorf("Hierarchy Controller is enabled on the ConfigManagement object. It must be disabled before migrating.")
+	}
 
 	fmt.Printf("Removing ConfigManagement on cluster %q ...\n", kubeCtx)
 	cmYamlFile, err := saveConfigManagementOperatorYaml(ctx, cc, kubeCtx)

cmd/nomos/util/configmanagement.go

@@ -202,6 +202,15 @@ func (c *ConfigManagementClient) RemoveFinalizers(ctx context.Context) error {
 	return err
 }
 
+// IsHNCEnabled returns if the ConfigManagement object has HNC enabled.
+func (c *ConfigManagementClient) IsHNCEnabled(ctx context.Context) (bool, error) {
+	isHNCEnabled, err := c.NestedBool(ctx, "spec", "hierarchyController", "enabled")
+	if err != nil {
+		return false, err
+	}
+	return isHNCEnabled, nil
+}
+
 // IsOssInstallation will check for the existence of ConfigManagement object, Operator deployment, and RootSync CRD
 // If RootSync CRD exist but ConfigManagement and Operator doesn't, it indicates an OSS installation
 func IsOssInstallation(ctx context.Context, c *ConfigManagementClient, cl client.Client, ck *kubernetes.Clientset) (bool, error) {

e2e/testcases/cli_test.go

@@ -1378,6 +1378,9 @@ func TestNomosMigrate(t *testing.T) {
 			},
 			"spec": map[string]interface{}{
 				"enableMultiRepo": true,
+				"hierarchyController": map[string]interface{}{
+					"enabled": true,
+				},
 			},
 		},
 	}
@@ -1395,6 +1398,33 @@ func TestNomosMigrate(t *testing.T) {
 			),
 		)))
 
+	nt.T.Log("Running nomos migrate should fail when HNC is enabled")
+	out, err := nt.Shell.Command("nomos", "migrate", "--remove-configmanagement").CombinedOutput()
+	if err != nil {
+		nt.T.Fatal(err)
+	}
+	assert.Contains(t, string(out), "Hierarchy Controller is enabled on the ConfigManagement object. It must be disabled before migrating.")
+
+	nt.T.Log("Disabling HNC")
+	cmObj = &unstructured.Unstructured{
+		Object: map[string]interface{}{
+			"apiVersion": "configmanagement.gke.io/v1",
+			"kind":       "ConfigManagement",
+			"metadata": map[string]interface{}{
+				"name": "config-management",
+			},
+			"spec": map[string]interface{}{
+				"enableMultiRepo": true,
+				"hierarchyController": map[string]interface{}{
+					"enabled": false,
+				},
+			},
+		},
+	}
+	nt.Must(nt.KubeClient.Apply(cmObj))
+	nt.Must(nt.Watcher.WatchForNotFound(kinds.Namespace(), "hnc-system", ""))
+	nt.Must(nt.Validate(util.ACMOperatorDeployment, configsync.ControllerNamespace, k8sobjects.DeploymentObject()))
+
 	nt.T.Log("Running nomos migrate to migrate from ConfigManagement to OSS install")
 	nt.Must(nt.Shell.Command("nomos", "migrate", "--remove-configmanagement").CombinedOutput())