HELM-611: add OCI registry client for chart operations (#15925)

* fix(helm): add OCI registry client for chart operations

OCI-based Helm charts were failing to install because the action
configuration lacked a registry client. This change:

- Add GetDefaultOCIRegistry() to create and attach a registry client
  to the Helm action configuration
- Integrate registry client initialization into all Helm handlers:
  install, upgrade, uninstall, rollback, and chart get operations
- Add unit tests for the new registry client function
- Update older tests to use mock registry Client function

Without a registry client, operations on OCI charts (oci://) would fail
with errors about missing registry support.

Fixes: HELM-611

* fix(helm): address review comments for OCI registry client

- Remove getDefaultRegistryClient from helm handler file.
- Rename insecure param to skipTLSVerify for clarity
- Add TLS skip verification and plainHTTP support
- Use mockable newRegistryClient for testability
- Fix variable naming (registryClient)
- Return nil directly instead of err variable

Author: sowmya-sl

pkg/helm/actions/config.go

@@ -50,6 +50,9 @@ func GetActionConfigurations(host, ns, token string, transport *http.RoundTrippe
 	}
 	conf := new(action.Configuration)
 	conf.Init(confFlags, ns, "secrets", klog.Infof)
-
+	err = GetDefaultOCIRegistry(conf)
+	if err != nil {
+		klog.V(4).Infof("Failed to get default OCI registry: %v", err)
+	}
 	return conf
 }

pkg/helm/actions/get_registry.go

@@ -0,0 +1,42 @@
+package actions
+
+import (
+	"crypto/tls"
+	"fmt"
+	"net/http"
+
+	"helm.sh/helm/v3/pkg/action"
+	"helm.sh/helm/v3/pkg/registry"
+)
+
+// newRegistryClient is a package-level variable to allow mocking in tests
+var newRegistryClient = registry.NewClient
+
+func GetDefaultOCIRegistry(conf *action.Configuration) error {
+	return GetOCIRegistry(conf, false, false)
+}
+
+func GetOCIRegistry(conf *action.Configuration, skipTLSVerify bool, plainHTTP bool) error {
+	if conf == nil {
+		return fmt.Errorf("action configuration cannot be nil")
+	}
+	opts := []registry.ClientOption{
+		registry.ClientOptDebug(false),
+	}
+	if plainHTTP {
+		opts = append(opts, registry.ClientOptPlainHTTP())
+	}
+	if skipTLSVerify {
+		transport := http.DefaultTransport.(*http.Transport).Clone()
+		transport.TLSClientConfig = &tls.Config{
+			InsecureSkipVerify: true,
+		}
+		opts = append(opts, registry.ClientOptHTTPClient(&http.Client{Transport: transport}))
+	}
+	registryClient, err := newRegistryClient(opts...)
+	if err != nil {
+		return fmt.Errorf("failed to create registry client: %w", err)
+	}
+	conf.RegistryClient = registryClient
+	return nil
+}

pkg/helm/actions/get_registry_test.go

@@ -0,0 +1,132 @@
+package actions
+
+import (
+	"errors"
+	"io"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+	"helm.sh/helm/v3/pkg/action"
+	"helm.sh/helm/v3/pkg/chartutil"
+	kubefake "helm.sh/helm/v3/pkg/kube/fake"
+	"helm.sh/helm/v3/pkg/registry"
+	"helm.sh/helm/v3/pkg/storage"
+	"helm.sh/helm/v3/pkg/storage/driver"
+)
+
+func TestGetDefaultOCIRegistry_Success(t *testing.T) {
+	store := storage.Init(driver.NewMemory())
+	conf := &action.Configuration{
+		RESTClientGetter: FakeConfig{},
+		Releases:         store,
+		KubeClient:       &kubefake.PrintingKubeClient{Out: io.Discard},
+		Capabilities:     chartutil.DefaultCapabilities,
+	}
+	require.Nil(t, conf.RegistryClient, "Registry Client should be nil")
+
+	// Store original values
+	originalReleases := conf.Releases
+	originalKubeClient := conf.KubeClient
+	originalCapabilities := conf.Capabilities
+
+	err := GetDefaultOCIRegistry(conf)
+	require.NoError(t, err)
+	require.NotNil(t, conf.RegistryClient, "Registry Client should not be nil")
+
+	// Verify other configuration fields are not modified.
+	require.Equal(t, originalReleases, conf.Releases, "Releases should not be modified")
+	require.Equal(t, originalKubeClient, conf.KubeClient, "KubeClient should not be modified")
+	require.Equal(t, originalCapabilities, conf.Capabilities, "Capabilities should not be modified")
+
+}
+
+func TestGetOCIRegistry_NilConfig(t *testing.T) {
+	err := GetOCIRegistry(nil, false, false)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "action configuration cannot be nil")
+}
+
+func TestGetOCIRegistry_Success(t *testing.T) {
+	tests := []struct {
+		name          string
+		skipTLSVerify bool
+		plainHTTP     bool
+	}{
+		{
+			name:          "default options",
+			skipTLSVerify: false,
+			plainHTTP:     false,
+		},
+		{
+			name:          "with skipTLSVerify",
+			skipTLSVerify: true,
+			plainHTTP:     false,
+		},
+		{
+			name:          "with plainHTTP",
+			skipTLSVerify: false,
+			plainHTTP:     true,
+		},
+		{
+			name:          "with both skipTLSVerify and plainHTTP",
+			skipTLSVerify: true,
+			plainHTTP:     true,
+		},
+	}
+	originalNewRegistryClient := newRegistryClient
+	defer func() {
+		newRegistryClient = originalNewRegistryClient
+	}()
+
+	for _, tt := range tests {
+		newRegistryClient = func(options ...registry.ClientOption) (*registry.Client, error) {
+			count := 0
+			if tt.plainHTTP {
+				count += 1
+			}
+			if tt.skipTLSVerify {
+				count += 1
+			}
+			require.Equal(t, count, len(options)-1, "Expected %d options, got %d", count, len(options))
+			return &registry.Client{}, nil
+		}
+		t.Run(tt.name, func(t *testing.T) {
+			store := storage.Init(driver.NewMemory())
+			conf := &action.Configuration{
+				RESTClientGetter: FakeConfig{},
+				Releases:         store,
+				KubeClient:       &kubefake.PrintingKubeClient{Out: io.Discard},
+				Capabilities:     chartutil.DefaultCapabilities,
+			}
+			require.Nil(t, conf.RegistryClient, "Registry Client should be nil initially")
+
+			err := GetOCIRegistry(conf, tt.skipTLSVerify, tt.plainHTTP)
+			require.NoError(t, err)
+			require.NotNil(t, conf.RegistryClient, "Registry Client should not be nil after GetOCIRegistry")
+		})
+	}
+}
+
+func TestGetOCIRegistry_NewClientError(t *testing.T) {
+	// Save original function and restore after test
+	originalNewRegistryClient := newRegistryClient
+	defer func() { newRegistryClient = originalNewRegistryClient }()
+
+	// Mock newRegistryClient to return an error
+	newRegistryClient = func(options ...registry.ClientOption) (*registry.Client, error) {
+		return nil, errors.New("mock registry client error")
+	}
+
+	store := storage.Init(driver.NewMemory())
+	conf := &action.Configuration{
+		RESTClientGetter: FakeConfig{},
+		Releases:         store,
+		KubeClient:       &kubefake.PrintingKubeClient{Out: io.Discard},
+		Capabilities:     chartutil.DefaultCapabilities,
+	}
+
+	err := GetOCIRegistry(conf, false, false)
+	require.Error(t, err)
+	require.Contains(t, err.Error(), "failed to create registry client")
+	require.Contains(t, err.Error(), "mock registry client error")
+}