Add support for deploying OCI helm charts in OLM v1

* added support for deploying OCI helm charts which sits behind
the HelmChartSupport feature gate
* extend the Cache Store() method to allow storing of Helm charts
* inspect chart archive contents
* added MediaType to the LayerData struct

Signed-off-by: Edmund Ochieng <ochienged@gmail.com>

Author: OchiengEd

internal/operator-controller/applier/helm.go

@@ -26,9 +26,11 @@ import (
 
 	ocv1 "github.com/operator-framework/operator-controller/api/v1"
 	"github.com/operator-framework/operator-controller/internal/operator-controller/authorization"
+	"github.com/operator-framework/operator-controller/internal/operator-controller/features"
 	"github.com/operator-framework/operator-controller/internal/operator-controller/rukpak/bundle/source"
 	"github.com/operator-framework/operator-controller/internal/operator-controller/rukpak/preflights/crdupgradesafety"
 	"github.com/operator-framework/operator-controller/internal/operator-controller/rukpak/util"
+	imageutil "github.com/operator-framework/operator-controller/internal/shared/util/image"
 )
 
 const (
@@ -209,6 +211,17 @@ func (h *Helm) buildHelmChart(bundleFS fs.FS, ext *ocv1.ClusterExtension) (*char
 	if err != nil {
 		return nil, err
 	}
+	if features.OperatorControllerFeatureGate.Enabled(features.HelmChartSupport) {
+		meta := new(chart.Metadata)
+		if ok, _ := imageutil.IsBundleSourceChart(bundleFS, meta); ok {
+			return imageutil.LoadChartFSWithOptions(
+				bundleFS,
+				fmt.Sprintf("%s-%s.tgz", meta.Name, meta.Version),
+				imageutil.WithInstallNamespace(ext.Spec.Namespace),
+			)
+		}
+	}
+
 	return h.BundleToHelmChartConverter.ToHelmChart(source.FromFS(bundleFS), ext.Spec.Namespace, watchNamespace)
 }
 

internal/operator-controller/features/features.go

@@ -16,6 +16,7 @@ const (
 	SyntheticPermissions              featuregate.Feature = "SyntheticPermissions"
 	WebhookProviderCertManager        featuregate.Feature = "WebhookProviderCertManager"
 	WebhookProviderOpenshiftServiceCA featuregate.Feature = "WebhookProviderOpenshiftServiceCA"
+	HelmChartSupport                  featuregate.Feature = "HelmChartSupport"
 )
 
 var operatorControllerFeatureGates = map[featuregate.Feature]featuregate.FeatureSpec{
@@ -63,6 +64,14 @@ var operatorControllerFeatureGates = map[featuregate.Feature]featuregate.Feature
 		PreRelease:    featuregate.Alpha,
 		LockToDefault: false,
 	},
+
+	// HelmChartSupport enables support for installing,
+	// updating and uninstalling Helm Charts via Cluster Extensions.
+	HelmChartSupport: {
+		Default:       false,
+		PreRelease:    featuregate.Alpha,
+		LockToDefault: false,
+	},
 }
 
 var OperatorControllerFeatureGate featuregate.MutableFeatureGate = featuregate.NewFeatureGate()

internal/shared/util/image/cache.go

@@ -16,16 +16,19 @@ import (
 	"github.com/containers/image/v5/docker/reference"
 	"github.com/opencontainers/go-digest"
 	ocispecv1 "github.com/opencontainers/image-spec/specs-go/v1"
+	"helm.sh/helm/v3/pkg/chart"
+	"helm.sh/helm/v3/pkg/registry"
 	"sigs.k8s.io/controller-runtime/pkg/log"
 
 	errorutil "github.com/operator-framework/operator-controller/internal/shared/util/error"
 	fsutil "github.com/operator-framework/operator-controller/internal/shared/util/fs"
 )
 
 type LayerData struct {
-	Reader io.Reader
-	Index  int
-	Err    error
+	MediaType string
+	Reader    io.Reader
+	Index     int
+	Err       error
 }
 
 type Cache interface {
@@ -128,8 +131,15 @@ func (a *diskCache) Store(ctx context.Context, ownerID string, srcRef reference.
 			if layer.Err != nil {
 				return fmt.Errorf("error reading layer[%d]: %w", layer.Index, layer.Err)
 			}
-			if _, err := archive.Apply(ctx, dest, layer.Reader, applyOpts...); err != nil {
-				return fmt.Errorf("error applying layer[%d]: %w", layer.Index, err)
+			switch layer.MediaType {
+			case registry.ChartLayerMediaType:
+				if err := storeChartLayer(dest, layer); err != nil {
+					return err
+				}
+			default:
+				if _, err := archive.Apply(ctx, dest, layer.Reader, applyOpts...); err != nil {
+					return fmt.Errorf("error applying layer[%d]: %w", layer.Index, err)
+				}
 			}
 			l.Info("applied layer", "layer", layer.Index)
 		}
@@ -147,6 +157,31 @@ func (a *diskCache) Store(ctx context.Context, ownerID string, srcRef reference.
 	return os.DirFS(dest), modTime, nil
 }
 
+func storeChartLayer(path string, layer LayerData) error {
+	data, err := io.ReadAll(layer.Reader)
+	if err != nil {
+		return fmt.Errorf("error reading layer[%d]: %w", layer.Index, layer.Err)
+	}
+	meta := new(chart.Metadata)
+	_, err = inspectChart(data, meta)
+	if err != nil {
+		return fmt.Errorf("inspecting chart layer: %w", err)
+	}
+	filename := filepath.Join(path,
+		fmt.Sprintf("%s-%s.tgz", meta.Name, meta.Version),
+	)
+	chart, err := os.Create(filename)
+	if err != nil {
+		return fmt.Errorf("inspecting chart layer: %w", err)
+	}
+	defer chart.Close()
+
+	if _, err := chart.Write(data); err != nil {
+		return fmt.Errorf("copying chart to the destination %s; %w", path, err)
+	}
+	return nil
+}
+
 func (a *diskCache) Delete(_ context.Context, ownerID string) error {
 	return fsutil.DeleteReadOnlyRecursive(a.ownerIDPath(ownerID))
 }

internal/shared/util/image/cache_test.go

@@ -2,6 +2,7 @@ package image
 
 import (
 	"archive/tar"
+	"bytes"
 	"context"
 	"errors"
 	"io"
@@ -20,6 +21,7 @@ import (
 	ocispecv1 "github.com/opencontainers/image-spec/specs-go/v1"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
+	"helm.sh/helm/v3/pkg/registry"
 
 	fsutil "github.com/operator-framework/operator-controller/internal/shared/util/fs"
 )
@@ -585,6 +587,53 @@ func TestDiskCacheGarbageCollection(t *testing.T) {
 	}
 }
 
+func Test_storeChartLayer(t *testing.T) {
+	tmpDir := t.TempDir()
+	testdataCharts := filepath.Join("../../../../", "testdata", "charts")
+	type args struct {
+		path  string
+		layer LayerData
+	}
+	type want struct {
+		err      error
+		filename string
+	}
+	tests := []struct {
+		name string
+		args args
+		want want
+	}{
+		{
+			name: "store helm chart layer to the filesystem",
+			args: args{
+				path: tmpDir,
+				layer: func() LayerData {
+					chart, _ := os.ReadFile(filepath.Join(testdataCharts, "sample-chart-0.1.0.tgz"))
+					return LayerData{
+						Index:     0,
+						MediaType: registry.ChartLayerMediaType,
+						Reader:    bytes.NewBuffer(chart),
+						Err:       nil,
+					}
+				}(),
+			},
+			want: want{
+				err:      nil,
+				filename: filepath.Join(tmpDir, "sample-chart-0.1.0.tgz"),
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			err := storeChartLayer(tc.args.path, tc.args.layer)
+			require.NoError(t, err, "write chart layer to the filesystem")
+			_, err = os.Stat(tc.want.filename)
+			require.NoError(t, err, "chart should exist in the filesystem")
+		})
+	}
+}
+
 func mustParseCanonical(t *testing.T, s string) reference.Canonical {
 	n, err := reference.ParseNamed(s)
 	require.NoError(t, err)