Merge pull request #13188 from srikiz/fix-kops-get-clusters-json-output

[Issue-12293] Fix json output to keep it consistent for single or multiple objects

cmd/kops/create_cluster.go

@@ -720,7 +720,7 @@ func RunCreateCluster(ctx context.Context, f *util.Factory, out io.Writer, c *Cr
 			}
 			return nil
 		case OutputJSON:
-			if err := fullOutputJSON(out, obj...); err != nil {
+			if err := fullOutputJSON(out, true, obj...); err != nil {
 				return fmt.Errorf("error writing cluster json to stdout: %v", err)
 			}
 			return nil

cmd/kops/create_instancegroup.go

@@ -221,7 +221,7 @@ func RunCreateInstanceGroup(ctx context.Context, f *util.Factory, out io.Writer,
 			}
 			return nil
 		case OutputJSON:
-			if err := fullOutputJSON(out, ig); err != nil {
+			if err := fullOutputJSON(out, true, ig); err != nil {
 				return fmt.Errorf("error writing cluster json to stdout: %v", err)
 			}
 			return nil

cmd/kops/get.go

@@ -158,7 +158,7 @@ func RunGet(ctx context.Context, f commandutils.Factory, out io.Writer, options
 		return nil
 
 	case OutputJSON:
-		if err := fullOutputJSON(out, allObjects...); err != nil {
+		if err := fullOutputJSON(out, false, allObjects...); err != nil {
 			return fmt.Errorf("error writing json to stdout: %v", err)
 		}
 		return nil

cmd/kops/get_cluster.go

@@ -123,17 +123,11 @@ func RunGetClusters(ctx context.Context, f commandutils.Factory, out io.Writer,
 		return err
 	}
 
+	singleClusterSelected := false
 	var clusterList []*kopsapi.Cluster
-	if len(options.ClusterNames) != 1 {
-		list, err := client.ListClusters(ctx, metav1.ListOptions{})
-		if err != nil {
-			return err
-		}
-		for i := range list.Items {
-			clusterList = append(clusterList, &list.Items[i])
-		}
-	} else {
+	if len(options.ClusterNames) == 1 {
 		// Optimization - avoid fetching all clusters if we're only querying one
+		singleClusterSelected = true
 		cluster, err := client.GetCluster(ctx, options.ClusterNames[0])
 		if err != nil {
 			if !apierrors.IsNotFound(err) {
@@ -142,6 +136,14 @@ func RunGetClusters(ctx context.Context, f commandutils.Factory, out io.Writer,
 		} else {
 			clusterList = append(clusterList, cluster)
 		}
+	} else {
+		list, err := client.ListClusters(ctx, metav1.ListOptions{})
+		if err != nil {
+			return err
+		}
+		for i := range list.Items {
+			clusterList = append(clusterList, &list.Items[i])
+		}
 	}
 
 	clusters, err := filterClustersByName(options.ClusterNames, clusterList)
@@ -176,7 +178,11 @@ func RunGetClusters(ctx context.Context, f commandutils.Factory, out io.Writer,
 	case OutputYaml:
 		return fullOutputYAML(out, obj...)
 	case OutputJSON:
-		return fullOutputJSON(out, obj...)
+		// if singleClusterSelected is true, only a single object is returned
+		// otherwise to keep it consistent, always returns an array.
+		// Ex: kops get clusters -ojson should will always return an array (even if 1 cluster is available)
+		// kops get cluster test.example.com -o json will return a single object (since a specific cluster is selected)
+		return fullOutputJSON(out, singleClusterSelected, obj...)
 	default:
 		return fmt.Errorf("Unknown output format: %q", options.Output)
 	}
@@ -227,12 +233,10 @@ func clusterOutputTable(clusters []*kopsapi.Cluster, out io.Writer) error {
 	return t.Render(clusters, out, "NAME", "CLOUD", "ZONES")
 }
 
-// fullOutputJson outputs the marshalled JSON of a list of clusters and instance groups.  It will handle
+// fullOutputJSON outputs the marshalled JSON of a list of clusters and instance groups.  It will handle
 // nils for clusters and instanceGroups slices.
-func fullOutputJSON(out io.Writer, args ...runtime.Object) error {
-	argsLen := len(args)
-
-	if argsLen > 1 {
+func fullOutputJSON(out io.Writer, singleObject bool, args ...runtime.Object) error {
+	if !singleObject {
 		if _, err := fmt.Fprint(out, "["); err != nil {
 			return err
 		}
@@ -249,7 +253,7 @@ func fullOutputJSON(out io.Writer, args ...runtime.Object) error {
 		}
 	}
 
-	if argsLen > 1 {
+	if !singleObject {
 		if _, err := fmt.Fprint(out, "]"); err != nil {
 			return err
 		}
@@ -258,7 +262,7 @@ func fullOutputJSON(out io.Writer, args ...runtime.Object) error {
 	return nil
 }
 
-// fullOutputJson outputs the marshalled JSON of a list of clusters and instance groups.  It will handle
+// fullOutputYAML outputs the marshalled JSON of a list of clusters and instance groups.  It will handle
 // nils for clusters and instanceGroups slices.
 func fullOutputYAML(out io.Writer, args ...runtime.Object) error {
 	for i, obj := range args {

cmd/kops/get_instancegroups.go

@@ -113,8 +113,12 @@ func RunGetInstanceGroups(ctx context.Context, f commandutils.Factory, out io.Wr
 		return err
 	}
 
+	singleObject := false
+
 	if len(instancegroups) == 0 {
 		return fmt.Errorf("no InstanceGroup objects found")
+	} else if len(instancegroups) == 1 {
+		singleObject = true
 	}
 
 	var obj []runtime.Object
@@ -130,7 +134,7 @@ func RunGetInstanceGroups(ctx context.Context, f commandutils.Factory, out io.Wr
 	case OutputYaml:
 		return fullOutputYAML(out, obj...)
 	case OutputJSON:
-		return fullOutputJSON(out, obj...)
+		return fullOutputJSON(out, singleObject, obj...)
 	default:
 		return fmt.Errorf("unknown output format: %q", options.Output)
 	}

cmd/kops/toolbox_instance-selector.go

@@ -332,7 +332,7 @@ func RunToolboxInstanceSelector(ctx context.Context, f *util.Factory, out io.Wri
 					return fmt.Errorf("error writing cluster yaml to stdout: %v", err)
 				}
 			case OutputJSON:
-				if err := fullOutputJSON(out, ig); err != nil {
+				if err := fullOutputJSON(out, true, ig); err != nil {
 					return fmt.Errorf("error writing cluster json to stdout: %v", err)
 				}
 			default:

docs/releases/1.23-NOTES.md

@@ -64,6 +64,8 @@ It is recommended to keep using the `v1alpha2` API version.
 
 * The `kops rolling-update cluster` command has a new `--drain-timeout` flag for specifying the maximum amount of time to wait when attempting to drain a node. Previously, rolling-updates would attempt to drain a node for an indefinite amount of time. If `--drain-timeout` is not specified, a default of 15 minutes is applied.
 
+* Fix inconsistent output of `kops get clusters -ojson`. This will now always return a list (irrespective of a single or multiple clusters) to keep the format consistent. However, note that `kops get cluster dev.example.com -ojson` will continue to work as previously, and will return a single object.
+
 # Full change list since 1.22.0 release