feat(cmd): put OCI commands behind a feature gate

This adds a new `gates` package used for interacting with feature gates. It also marks the OCI registry work as experimental, signalling to users that it is not a stable feature of Helm.

Signed-off-by: Matthew Fisher <matt.fisher@microsoft.com>

cmd/helm/chart.go

@@ -33,9 +33,11 @@ Example usage:
 
 func newChartCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	cmd := &cobra.Command{
-		Use:   "chart",
+		Use:               "chart",
-		Short: "push, pull, tag, or remove Helm charts",
+		Short:             "push, pull, tag, or remove Helm charts",
-		Long:  chartHelp,
+		Long:              chartHelp,
+		Hidden:            !FeatureGateOCI.IsEnabled(),
+		PersistentPreRunE: checkOCIFeatureGate(),
 	}
 	cmd.AddCommand(
 		newChartListCmd(cfg, out),

cmd/helm/chart_export.go

@@ -35,10 +35,11 @@ and check into source control if desired.
 
 func newChartExportCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	return &cobra.Command{
-		Use:   "export [ref]",
+		Use:    "export [ref]",
-		Short: "export a chart to directory",
+		Short:  "export a chart to directory",
-		Long:  chartExportDesc,
+		Long:   chartExportDesc,
-		Args:  require.MinimumNArgs(1),
+		Args:   require.MinimumNArgs(1),
+		Hidden: !FeatureGateOCI.IsEnabled(),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			ref := args[0]
 			return action.NewChartExport(cfg).Run(out, ref)

cmd/helm/chart_list.go

@@ -36,6 +36,7 @@ func newChartListCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 		Aliases: []string{"ls"},
 		Short:   "list all saved charts",
 		Long:    chartListDesc,
+		Hidden:  !FeatureGateOCI.IsEnabled(),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			return action.NewChartList(cfg).Run(out)
 		},

cmd/helm/chart_pull.go

@@ -33,10 +33,11 @@ This will store the chart in the local registry cache to be used later.
 
 func newChartPullCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	return &cobra.Command{
-		Use:   "pull [ref]",
+		Use:    "pull [ref]",
-		Short: "pull a chart from remote",
+		Short:  "pull a chart from remote",
-		Long:  chartPullDesc,
+		Long:   chartPullDesc,
-		Args:  require.MinimumNArgs(1),
+		Args:   require.MinimumNArgs(1),
+		Hidden: !FeatureGateOCI.IsEnabled(),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			ref := args[0]
 			return action.NewChartPull(cfg).Run(out, ref)

cmd/helm/chart_push.go

@@ -35,10 +35,11 @@ Must first run "helm chart save" or "helm chart pull".
 
 func newChartPushCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	return &cobra.Command{
-		Use:   "push [ref]",
+		Use:    "push [ref]",
-		Short: "push a chart to remote",
+		Short:  "push a chart to remote",
-		Long:  chartPushDesc,
+		Long:   chartPushDesc,
-		Args:  require.MinimumNArgs(1),
+		Args:   require.MinimumNArgs(1),
+		Hidden: !FeatureGateOCI.IsEnabled(),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			ref := args[0]
 			return action.NewChartPush(cfg).Run(out, ref)

cmd/helm/chart_remove.go

@@ -41,6 +41,7 @@ func newChartRemoveCmd(cfg *action.Configuration, out io.Writer) *cobra.Command
 		Short:   "remove a chart",
 		Long:    chartRemoveDesc,
 		Args:    require.MinimumNArgs(1),
+		Hidden:  !FeatureGateOCI.IsEnabled(),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			ref := args[0]
 			return action.NewChartRemove(cfg).Run(out, ref)

cmd/helm/chart_save.go

@@ -36,10 +36,11 @@ not change the item as it exists in the cache.
 
 func newChartSaveCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	return &cobra.Command{
-		Use:   "save [path] [ref]",
+		Use:    "save [path] [ref]",
-		Short: "save a chart directory",
+		Short:  "save a chart directory",
-		Long:  chartSaveDesc,
+		Long:   chartSaveDesc,
-		Args:  require.MinimumNArgs(2),
+		Args:   require.MinimumNArgs(2),
+		Hidden: !FeatureGateOCI.IsEnabled(),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			path := args[0]
 			ref := args[1]

cmd/helm/helm.go

@@ -24,6 +24,7 @@ import (
 	"strings"
 	"sync"
 
+	"github.com/spf13/cobra"
 	"github.com/spf13/pflag"
 	"k8s.io/cli-runtime/pkg/genericclioptions"
 	"k8s.io/klog"
@@ -33,11 +34,15 @@ import (
 
 	"helm.sh/helm/pkg/action"
 	"helm.sh/helm/pkg/cli"
+	"helm.sh/helm/pkg/gates"
 	"helm.sh/helm/pkg/kube"
 	"helm.sh/helm/pkg/storage"
 	"helm.sh/helm/pkg/storage/driver"
 )
 
+// FeatureGateOCI is the feature gate for checking if `helm chart` and `helm registry` commands should work
+const FeatureGateOCI = gates.Gate("HELM_EXPERIMENTAL_OCI")
+
 var (
 	settings   cli.EnvSettings
 	config     genericclioptions.RESTClientGetter
@@ -134,3 +139,12 @@ func getNamespace() string {
 func wordSepNormalizeFunc(f *pflag.FlagSet, name string) pflag.NormalizedName {
 	return pflag.NormalizedName(strings.ReplaceAll(name, "_", "-"))
 }
+
+func checkOCIFeatureGate() func(_ *cobra.Command, _ []string) error {
+	return func(_ *cobra.Command, _ []string) error {
+		if !FeatureGateOCI.IsEnabled() {
+			return FeatureGateOCI.Error()
+		}
+		return nil
+	}
+}

cmd/helm/registry.go

@@ -33,9 +33,11 @@ Example usage:
 
 func newRegistryCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	cmd := &cobra.Command{
-		Use:   "registry",
+		Use:               "registry",
-		Short: "login to or logout from a registry",
+		Short:             "login to or logout from a registry",
-		Long:  registryHelp,
+		Long:              registryHelp,
+		Hidden:            !FeatureGateOCI.IsEnabled(),
+		PersistentPreRunE: checkOCIFeatureGate(),
 	}
 	cmd.AddCommand(
 		newRegistryLoginCmd(cfg, out),

cmd/helm/registry_login.go

@@ -41,10 +41,11 @@ func newRegistryLoginCmd(cfg *action.Configuration, out io.Writer) *cobra.Comman
 	var passwordFromStdinOpt bool
 
 	cmd := &cobra.Command{
-		Use:   "login [host]",
+		Use:    "login [host]",
-		Short: "login to a registry",
+		Short:  "login to a registry",
-		Long:  registryLoginDesc,
+		Long:   registryLoginDesc,
-		Args:  require.MinimumNArgs(1),
+		Args:   require.MinimumNArgs(1),
+		Hidden: !FeatureGateOCI.IsEnabled(),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			hostname := args[0]
 

cmd/helm/registry_logout.go

@@ -31,10 +31,11 @@ Remove credentials stored for a remote registry.
 
 func newRegistryLogoutCmd(cfg *action.Configuration, out io.Writer) *cobra.Command {
 	return &cobra.Command{
-		Use:   "logout [host]",
+		Use:    "logout [host]",
-		Short: "logout from a registry",
+		Short:  "logout from a registry",
-		Long:  registryLogoutDesc,
+		Long:   registryLogoutDesc,
-		Args:  require.MinimumNArgs(1),
+		Args:   require.MinimumNArgs(1),
+		Hidden: !FeatureGateOCI.IsEnabled(),
 		RunE: func(cmd *cobra.Command, args []string) error {
 			hostname := args[0]
 			return action.NewRegistryLogout(cfg).Run(out, hostname)

cmd/helm/root.go

@@ -25,9 +25,9 @@ import (
 	"github.com/spf13/cobra"
 
 	"helm.sh/helm/cmd/helm/require"
+	"helm.sh/helm/internal/experimental/registry"
 	"helm.sh/helm/pkg/action"
 	"helm.sh/helm/pkg/helmpath"
-	"helm.sh/helm/pkg/registry"
 )
 
 const (

internal/experimental/registry/authorizer.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package registry // import "helm.sh/helm/pkg/registry"
+package registry // import "helm.sh/helm/internal/experimental/registry"
 
 import (
 	"github.com/deislabs/oras/pkg/auth"

internal/experimental/registry/cache.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package registry // import "helm.sh/helm/pkg/registry"
+package registry // import "helm.sh/helm/internal/experimental/registry"
 
 import (
 	"bytes"

internal/experimental/registry/client.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package registry // import "helm.sh/helm/pkg/registry"
+package registry // import "helm.sh/helm/internal/experimental/registry"
 
 import (
 	"context"

internal/experimental/registry/constants.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package registry // import "helm.sh/helm/pkg/registry"
+package registry // import "helm.sh/helm/internal/experimental/registry"
 
 const (
 	// HelmChartConfigMediaType is the reserved media type for the Helm chart manifest config

internal/experimental/registry/reference.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package registry // import "helm.sh/helm/pkg/registry"
+package registry // import "helm.sh/helm/internal/experimental/registry"
 
 import (
 	"errors"

internal/experimental/registry/resolver.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package registry // import "helm.sh/helm/pkg/registry"
+package registry // import "helm.sh/helm/internal/experimental/registry"
 
 import (
 	"github.com/containerd/containerd/remotes"

pkg/action/action.go

@@ -30,10 +30,10 @@ import (
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 
+	"helm.sh/helm/internal/experimental/registry"
 	"helm.sh/helm/pkg/chartutil"
 	"helm.sh/helm/pkg/hooks"
 	"helm.sh/helm/pkg/kube"
-	"helm.sh/helm/pkg/registry"
 	"helm.sh/helm/pkg/release"
 	"helm.sh/helm/pkg/storage"
 )

pkg/action/action_test.go

@@ -25,10 +25,10 @@ import (
 	dockerauth "github.com/deislabs/oras/pkg/auth/docker"
 	fakeclientset "k8s.io/client-go/kubernetes/fake"
 
+	"helm.sh/helm/internal/experimental/registry"
 	"helm.sh/helm/pkg/chart"
 	"helm.sh/helm/pkg/chartutil"
 	kubefake "helm.sh/helm/pkg/kube/fake"
-	"helm.sh/helm/pkg/registry"
 	"helm.sh/helm/pkg/release"
 	"helm.sh/helm/pkg/storage"
 	"helm.sh/helm/pkg/storage/driver"

pkg/action/chart_export.go

@@ -20,8 +20,8 @@ import (
 	"fmt"
 	"io"
 
+	"helm.sh/helm/internal/experimental/registry"
 	"helm.sh/helm/pkg/chartutil"
-	"helm.sh/helm/pkg/registry"
 )
 
 // ChartExport performs a chart export operation.

pkg/action/chart_pull.go

@@ -19,7 +19,7 @@ package action
 import (
 	"io"
 
-	"helm.sh/helm/pkg/registry"
+	"helm.sh/helm/internal/experimental/registry"
 )
 
 // ChartPull performs a chart pull operation.

pkg/action/chart_push.go

@@ -19,7 +19,7 @@ package action
 import (
 	"io"
 
-	"helm.sh/helm/pkg/registry"
+	"helm.sh/helm/internal/experimental/registry"
 )
 
 // ChartPush performs a chart push operation.

pkg/action/chart_remove.go

@@ -19,7 +19,7 @@ package action
 import (
 	"io"
 
-	"helm.sh/helm/pkg/registry"
+	"helm.sh/helm/internal/experimental/registry"
 )
 
 // ChartRemove performs a chart remove operation.

pkg/action/chart_save.go

@@ -19,8 +19,8 @@ package action
 import (
 	"io"
 
+	"helm.sh/helm/internal/experimental/registry"
 	"helm.sh/helm/pkg/chart"
-	"helm.sh/helm/pkg/registry"
 )
 
 // ChartSave performs a chart save operation.

pkg/action/chart_save_test.go

@@ -20,7 +20,7 @@ import (
 	"io/ioutil"
 	"testing"
 
-	"helm.sh/helm/pkg/registry"
+	"helm.sh/helm/internal/experimental/registry"
 )
 
 func chartSaveAction(t *testing.T) *ChartSave {

pkg/gates/doc.go

@@ -0,0 +1,20 @@
+/*
+Copyright The Helm Authors.
+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 gates provides a general tool for working with experimental feature gates.
+
+This provides convenience methods where the user can determine if certain experimental features are enabled.
+*/
+package gates

pkg/gates/gates.go

@@ -0,0 +1,38 @@
+/*
+Copyright The Helm Authors.
+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 gates
+
+import (
+	"fmt"
+	"os"
+)
+
+// Gate is the name of the feature gate.
+type Gate string
+
+// String returns the string representation of this feature gate.
+func (g Gate) String() string {
+	return string(g)
+}
+
+// IsEnabled determines whether a certain feature gate is enabled.
+func (g Gate) IsEnabled() bool {
+	return os.Getenv(string(g)) != ""
+}
+
+func (g Gate) Error() error {
+	return fmt.Errorf("this feature has been marked as experimental and is not enabled by default. Please set $%s in your environment to use this feature", g.String())
+}

pkg/gates/gates_test.go

@@ -0,0 +1,47 @@
+/*
+Copyright The Helm Authors.
+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 gates
+
+import (
+	"os"
+	"testing"
+)
+
+const name string = "HELM_EXPERIMENTAL_FEATURE"
+
+func TestIsEnabled(t *testing.T) {
+	os.Unsetenv(name)
+	g := Gate(name)
+
+	if g.IsEnabled() {
+		t.Errorf("feature gate shows as available, but the environment variable $%s was not set", name)
+	}
+
+	os.Setenv(name, "1")
+
+	if !g.IsEnabled() {
+		t.Errorf("feature gate shows as disabled, but the environment variable $%s was set", name)
+	}
+}
+
+func TestError(t *testing.T) {
+	os.Unsetenv(name)
+	g := Gate(name)
+
+	if g.Error().Error() != "this feature has been marked as experimental and is not enabled by default. Please set $HELM_EXPERIMENTAL_FEATURE in your environment to use this feature" {
+		t.Errorf("incorrect error message. Received %s", g.Error().Error())
+	}
+}