Add flag --unsupported-addon-features to operator binary

* enable istio-csr controller only when the feature gate is enabled

Signed-off-by: Swarup Ghosh <[email protected]>

Author: swghosh

api/operator/v1alpha1/features.go

@@ -0,0 +1,22 @@
+package v1alpha1
+
+import (
+	"k8s.io/component-base/featuregate"
+)
+
+var (
+	// TechPreview: v1.15
+	//
+	// IstioCSR enables the controller for istiocsr.operator.openshift.io resource,
+	// which extends cert-manager-operator to deploy and manage the istio-csr agent.
+	// OpenShift Service Mesh facilitates the integration and istio-csr is an agent that
+	// allows Istio workload and control plane components to be secured using cert-manager.
+	//
+	// For more details,
+	// https://github.com/openshift/enhancements/blob/master/enhancements/cert-manager/istio-csr-controller.md
+	FeatureIstioCSR featuregate.Feature = "IstioCSR"
+)
+
+var OperatorFeatureGates = map[featuregate.Feature]featuregate.FeatureSpec{
+	FeatureIstioCSR: {Default: false, PreRelease: "TechPreview"},
+}

pkg/cmd/operator/cmd.go

@@ -20,5 +20,16 @@ func NewOperator() *cobra.Command {
 	cmd.Short = "Start the cert-manager Operator"
 	cmd.Flags().StringVar(&operator.TrustedCAConfigMapName, "trusted-ca-configmap", "", "The name of the config map containing TLS CA(s) which should be trusted by the controller's containers. PEM encoded file under \"ca-bundle.crt\" key is expected.")
 	cmd.Flags().StringVar(&operator.CloudCredentialSecret, "cloud-credentials-secret", "", "The name of the secret containing cloud credentials for authenticating using cert-manager ambient credentials mode.")
+
+	cmd.Flags().StringVar(&operator.UnsupportedAddonFeatures, "unsupported-addon-features", "",
+		`List of unsupported addon features that the operator optionally enables.
+		
+eg. --unsupported-addon-features="IstioCSR=true"
+		
+Note: Technology Preview features are not supported with Red Hat production service level agreements (SLAs)
+and might not be functionally complete. Red Hat does not recommend using them in production.
+
+These features provide early access to upcoming product features,
+enabling customers to test functionality and provide feedback during the development process.`)
 	return cmd
 }

pkg/features/features.go

@@ -0,0 +1,24 @@
+package features
+
+import (
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/component-base/featuregate"
+
+	"github.com/openshift/cert-manager-operator/api/operator/v1alpha1"
+)
+
+var (
+	// mutableFeatureGate is the top-level FeatureGate with mutability (read/write).
+	mutableFeatureGate featuregate.MutableFeatureGate = featuregate.NewFeatureGate()
+
+	// DefaultFeatureGate is the top-level shared global FeatureGate (read-only).
+	DefaultFeatureGate featuregate.FeatureGate = mutableFeatureGate
+)
+
+func init() {
+	utilruntime.Must(mutableFeatureGate.Add(v1alpha1.OperatorFeatureGates))
+}
+
+func SetupWithFlagValue(flagValue string) error {
+	return mutableFeatureGate.Set(flagValue)
+}

pkg/features/features_test.go

@@ -0,0 +1,93 @@
+package features
+
+import (
+	"fmt"
+	"strings"
+	"testing"
+
+	"k8s.io/component-base/featuregate"
+
+	"github.com/stretchr/testify/assert"
+)
+
+// expectedDefaultFeatureState is a map of features with known states
+//
+// Always update this test map when adding a new FeatureName to the api,
+// a test is added below to enforce this.
+var expectedDefaultFeatureState = map[bool][]featuregate.Feature{
+	// features ENABLED by default,
+	// list of features which are expected to be enabled at runtime.
+	true: {},
+
+	// features DISABLED by default,
+	// list of features which are expected to be disabled at runtime.
+	false: {
+		featuregate.Feature("IstioCSR"),
+	},
+}
+
+func TestFeatureGates(t *testing.T) {
+	t.Run("runtime features to test should be identical with operator features", func(t *testing.T) {
+		testFeatureNames := make([]featuregate.Feature, 0)
+		for _, featureNames := range expectedDefaultFeatureState {
+			testFeatureNames = append(testFeatureNames, featureNames...)
+		}
+
+		knownOperatorFeatures := make([]featuregate.Feature, 0)
+		feats := mutableFeatureGate.GetAll()
+		for feat := range feats {
+			// skip "AllBeta", "AllAlpha": our operator does not use those
+			if feat == "AllBeta" || feat == "AllAlpha" {
+				continue
+			}
+			knownOperatorFeatures = append(knownOperatorFeatures, feat)
+		}
+
+		assert.Equal(t, knownOperatorFeatures, testFeatureNames,
+			`the list of features known to the operator differ from what is being tested here,
+			it could be that there was a new Feature added to the api which wasn't added to the tests.
+			Please verify "api/operator/v1alpha1" and "pkg/operator/features" have identical features.`)
+	})
+
+	t.Run("all runtime features should honor expected default feature state", func(t *testing.T) {
+		for expectedDefaultState, features := range expectedDefaultFeatureState {
+			for _, featureName := range features {
+				assert.Equal(t, expectedDefaultState, DefaultFeatureGate.Enabled(featureName),
+					"violated by feature=%s", featureName)
+			}
+		}
+	})
+
+	t.Run("all TechPreview features should be disabled by default", func(t *testing.T) {
+		feats := mutableFeatureGate.GetAll()
+		for feat, spec := range feats {
+			// skip "AllBeta", "AllAlpha": our operator does not use those
+			if feat == "AllBeta" || feat == "AllAlpha" {
+				continue
+			}
+
+			assert.Equal(t, spec.PreRelease == "TechPreview", !spec.Default,
+				"prerelease TechPreview %q feature should default to disabled",
+				feat)
+		}
+	})
+
+	t.Run("runtime features should allow enabling all feature gates that are disabled by default", func(t *testing.T) {
+		// enable all disabled features
+		defaultDisabledFeatures := expectedDefaultFeatureState[false]
+
+		featVals := make([]string, len(defaultDisabledFeatures))
+		for i := range featVals {
+			featVals[i] = fmt.Sprintf("%s=true", defaultDisabledFeatures[i])
+		}
+
+		err := mutableFeatureGate.Set(strings.Join(featVals, ","))
+		assert.NoError(t, err)
+
+		// check if all those features were enabled successfully
+		for _, featureName := range defaultDisabledFeatures {
+			assert.Equal(t, true, DefaultFeatureGate.Enabled(featureName),
+				"violated by feature=%s", featureName)
+		}
+	})
+}

pkg/operator/starter.go

@@ -17,7 +17,9 @@ import (
 	"github.com/openshift/library-go/pkg/operator/status"
 	"github.com/openshift/library-go/pkg/operator/v1helpers"
 
+	"github.com/openshift/cert-manager-operator/api/operator/v1alpha1"
 	"github.com/openshift/cert-manager-operator/pkg/controller/deployment"
+	"github.com/openshift/cert-manager-operator/pkg/features"
 	certmanoperatorclient "github.com/openshift/cert-manager-operator/pkg/operator/clientset/versioned"
 	certmanoperatorinformers "github.com/openshift/cert-manager-operator/pkg/operator/informers/externalversions"
 	"github.com/openshift/cert-manager-operator/pkg/operator/operatorclient"
@@ -35,6 +37,10 @@ var TrustedCAConfigMapName string
 // used in ambient credentials mode, and is provided as a runtime arg
 var CloudCredentialSecret string
 
+// UnsupportedAddonFeatures is the user-specific list of unsupported addon features
+// that the operator optionally enables, and is provided as a runtime arg.
+var UnsupportedAddonFeatures string
+
 func RunOperator(ctx context.Context, cc *controllercmd.ControllerContext) error {
 	kubeClient, err := kubernetes.NewForConfig(cc.ProtoKubeConfig)
 	if err != nil {
@@ -112,12 +118,21 @@ func RunOperator(ctx context.Context, cc *controllercmd.ControllerContext) error
 		go controller.Run(ctx, 1)
 	}
 
-	manager, err := NewControllerManager()
+	err = features.SetupWithFlagValue(UnsupportedAddonFeatures)
 	if err != nil {
-		return fmt.Errorf("failed to create controller manager: %w", err)
+		return fmt.Errorf("failed to parse addon features: %w", err)
 	}
-	if err := manager.Start(ctrl.SetupSignalHandler()); err != nil {
-		return fmt.Errorf("failed to start istiocsr controller: %w", err)
+
+	// enable controller-runtime and istio-csr controller
+	// only when "IstioCSR" feature is turned on from --addon-features
+	if features.DefaultFeatureGate.Enabled(v1alpha1.FeatureIstioCSR) {
+		manager, err := NewControllerManager()
+		if err != nil {
+			return fmt.Errorf("failed to create controller manager: %w", err)
+		}
+		if err := manager.Start(ctrl.SetupSignalHandler()); err != nil {
+			return fmt.Errorf("failed to start istiocsr controller: %w", err)
+		}
 	}
 
 	<-ctx.Done()