enable openapiv3 by default

staging/src/k8s.io/kubectl/pkg/cmd/explain/explain.go

@@ -68,10 +68,6 @@ type ExplainOptions struct {
 	Mapper meta.RESTMapper
 	Schema openapi.Resources
 
-	// Toggles whether the OpenAPI v3 template-based renderer should be used to show
-	// output.
-	EnableOpenAPIV3 bool
-
 	// Name of the template to use with the openapiv3 template renderer. If
 	// `EnableOpenAPIV3` is disabled, this does nothing
 	OutputFormat string
@@ -82,10 +78,9 @@ type ExplainOptions struct {
 
 func NewExplainOptions(parent string, streams genericclioptions.IOStreams) *ExplainOptions {
 	return &ExplainOptions{
-		IOStreams:       streams,
+		IOStreams:    streams,
-		CmdParent:       parent,
+		CmdParent:    parent,
-		EnableOpenAPIV3: cmdutil.ExplainOpenapiV3.IsEnabled(),
+		OutputFormat: plaintextTemplateName,
-		OutputFormat:    plaintextTemplateName,
 	}
 }
 
@@ -109,9 +104,7 @@ func NewCmdExplain(parent string, f cmdutil.Factory, streams genericclioptions.I
 	cmd.Flags().StringVar(&o.APIVersion, "api-version", o.APIVersion, "Get different explanations for particular API version (API group/version)")
 
 	// Only enable --output as a valid flag if the feature is enabled
-	if o.EnableOpenAPIV3 {
+	cmd.Flags().StringVar(&o.OutputFormat, "output", plaintextTemplateName, "Format in which to render the schema (plaintext, plaintext-openapiv2)")
-		cmd.Flags().StringVar(&o.OutputFormat, "output", plaintextTemplateName, "Format in which to render the schema (plaintext, plaintext-openapiv2)")
-	}
 
 	return cmd
 }
@@ -128,12 +121,10 @@ func (o *ExplainOptions) Complete(f cmdutil.Factory, cmd *cobra.Command, args []
 		return err
 	}
 
-	// Only openapi v3 needs the openapiv3client
+	// Only openapi v3 needs the discovery client.
-	if o.EnableOpenAPIV3 {
+	o.OpenAPIV3Client, err = f.OpenAPIV3Client()
-		o.OpenAPIV3Client, err = f.OpenAPIV3Client()
+	if err != nil {
-		if err != nil {
+		return err
-			return err
-		}
 	}
 
 	o.args = args
@@ -172,39 +163,36 @@ func (o *ExplainOptions) Run() error {
 	}
 
 	// Fallback to openapiv2 implementation using special template name
-	if o.EnableOpenAPIV3 {
+	switch o.OutputFormat {
-		switch o.OutputFormat {
+	case plaintextOpenAPIV2TemplateName:
-		case plaintextOpenAPIV2TemplateName:
+		return o.renderOpenAPIV2(fullySpecifiedGVR, fieldsPath)
+	case plaintextTemplateName:
+		// Check whether the server reponds to OpenAPIV3.
+		if _, err := o.OpenAPIV3Client.Paths(); err != nil {
+			// Use v2 renderer if server does not support v3
 			return o.renderOpenAPIV2(fullySpecifiedGVR, fieldsPath)
-		case plaintextTemplateName:
-			// Check whether the server reponds to OpenAPIV3.
-			if _, err := o.OpenAPIV3Client.Paths(); err != nil {
-				// Use v2 renderer if server does not support v3
-				return o.renderOpenAPIV2(fullySpecifiedGVR, fieldsPath)
-			}
-
-			fallthrough
-		default:
-			if len(o.APIVersion) > 0 {
-				apiVersion, err := schema.ParseGroupVersion(o.APIVersion)
-				if err != nil {
-					return err
-				}
-				fullySpecifiedGVR.Group = apiVersion.Group
-				fullySpecifiedGVR.Version = apiVersion.Version
-			}
-
-			return openapiv3explain.PrintModelDescription(
-				fieldsPath,
-				o.Out,
-				o.OpenAPIV3Client,
-				fullySpecifiedGVR,
-				o.Recursive,
-				o.OutputFormat,
-			)
 		}
+
+		fallthrough
+	default:
+		if len(o.APIVersion) > 0 {
+			apiVersion, err := schema.ParseGroupVersion(o.APIVersion)
+			if err != nil {
+				return err
+			}
+			fullySpecifiedGVR.Group = apiVersion.Group
+			fullySpecifiedGVR.Version = apiVersion.Version
+		}
+
+		return openapiv3explain.PrintModelDescription(
+			fieldsPath,
+			o.Out,
+			o.OpenAPIV3Client,
+			fullySpecifiedGVR,
+			o.Recursive,
+			o.OutputFormat,
+		)
 	}
-	return o.renderOpenAPIV2(fullySpecifiedGVR, fieldsPath)
 }
 
 func (o *ExplainOptions) renderOpenAPIV2(

staging/src/k8s.io/kubectl/pkg/cmd/explain/explain_test.go

@@ -22,7 +22,6 @@ import (
 	"regexp"
 	"testing"
 
-	"github.com/stretchr/testify/require"
 	"k8s.io/apimachinery/pkg/api/meta"
 	sptest "k8s.io/apimachinery/pkg/util/strategicpatch/testing"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
@@ -278,21 +277,3 @@ func runExplainTestCases(t *testing.T, cases []explainTestCase) {
 		buf.Reset()
 	}
 }
-
-func TestAlphaEnablement(t *testing.T) {
-	alphas := map[cmdutil.FeatureGate]string{
-		cmdutil.ExplainOpenapiV3: "output",
-	}
-	for feature, flag := range alphas {
-		f := cmdtesting.NewTestFactory()
-		defer f.Cleanup()
-
-		cmd := explain.NewCmdExplain("kubectl", f, genericclioptions.NewTestIOStreamsDiscard())
-		require.Nil(t, cmd.Flags().Lookup(flag), "flag %q should not be registered without the %q feature enabled", flag, feature)
-
-		cmdtesting.WithAlphaEnvs([]cmdutil.FeatureGate{feature}, t, func(t *testing.T) {
-			cmd := explain.NewCmdExplain("kubectl", f, genericclioptions.NewTestIOStreamsDiscard())
-			require.NotNil(t, cmd.Flags().Lookup(flag), "flag %q should be registered with the %q feature enabled", flag, feature)
-		})
-	}
-}