Implement feature gating from flags

This change reads in feature gates from `-feature-gates` and passes them
to the machine controller.

Author: theobarberbany

Diff for: cmd/manager/main.go

@@ -17,20 +17,24 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"strings"
 	"time"
 
 	configv1 "github.com/openshift/api/config/v1"
+	apifeatures "github.com/openshift/api/features"
 	machinev1 "github.com/openshift/api/machine/v1"
 	machinev1beta1 "github.com/openshift/api/machine/v1beta1"
+	"github.com/openshift/library-go/pkg/features"
 	"github.com/openshift/machine-api-operator/pkg/controller/machine"
 	"github.com/openshift/machine-api-operator/pkg/metrics"
 	machineactuator "github.com/openshift/machine-api-provider-aws/pkg/actuators/machine"
 	machinesetcontroller "github.com/openshift/machine-api-provider-aws/pkg/actuators/machineset"
 	awsclient "github.com/openshift/machine-api-provider-aws/pkg/client"
 	"github.com/openshift/machine-api-provider-aws/pkg/version"
 	corev1 "k8s.io/api/core/v1"
+	"k8s.io/apiserver/pkg/util/feature"
 	_ "k8s.io/client-go/plugin/pkg/client/auth/gcp"
-	k8sflag "k8s.io/component-base/cli/flag"
+	"k8s.io/component-base/featuregate"
 	"k8s.io/klog/v2"
 	"k8s.io/klog/v2/klogr"
 	ctrl "sigs.k8s.io/controller-runtime"
@@ -93,8 +97,15 @@ func main() {
 		"The address for health checking.",
 	)
 
-	featureGateArgs := map[string]bool{}
-	flag.Var(k8sflag.NewMapStringBool(&featureGateArgs), "feature-gates", "A set of key=value pairs that describe feature gates for alpha/experimen")
+	// Sets up feature gates
+	defaultMutableGate := feature.DefaultMutableFeatureGate
+	gateOpts, err := features.NewFeatureGateOptions(defaultMutableGate, apifeatures.SelfManaged, apifeatures.FeatureGateMachineAPIMigration)
+	if err != nil {
+		klog.Fatalf("Error setting up feature gates: %v", err)
+	}
+
+	// Add the --feature-gates flag
+	gateOpts.AddFlagsToGoFlagSet(nil)
 
 	klog.InitFlags(nil)
 	flag.Set("logtostderr", "true")
@@ -137,6 +148,18 @@ func main() {
 		klog.Infof("Watching machine-api objects only in namespace %q for reconciliation.", *watchNamespace)
 	}
 
+	// Sets feature gates from flags
+	klog.Infof("Initializing feature gates: %s", strings.Join(defaultMutableGate.KnownFeatures(), ", "))
+	warnings, err := gateOpts.ApplyTo(defaultMutableGate)
+	if err != nil {
+		klog.Fatalf("Error setting feature gates from flags: %v", err)
+	}
+	if len(warnings) > 0 {
+		klog.Infof("Warnings setting feature gates from flags: %v", warnings)
+	}
+
+	klog.Infof("FeatureGateMachineAPIMigration initialised: %t", defaultMutableGate.Enabled(featuregate.Feature(apifeatures.FeatureGateMachineAPIMigration)))
+
 	mgr, err := manager.New(cfg, opts)
 	if err != nil {
 		klog.Fatalf("Error creating manager: %v", err)
@@ -175,7 +198,7 @@ func main() {
 		RegionCache:         describeRegionsCache,
 	})
 
-	if err := machine.AddWithActuator(mgr, machineActuator); err != nil {
+	if err := machine.AddWithActuator(mgr, machineActuator, defaultMutableGate); err != nil {
 		klog.Fatalf("Error adding actuator: %v", err)
 	}
 

Diff for: pkg/actuators/machine/controller_test.go

@@ -12,6 +12,7 @@ import (
 	configv1 "github.com/openshift/api/config/v1"
 	machinev1beta1 "github.com/openshift/api/machine/v1beta1"
 	machinecontroller "github.com/openshift/machine-api-operator/pkg/controller/machine"
+	testutils "github.com/openshift/machine-api-operator/pkg/util/testing"
 	awsclient "github.com/openshift/machine-api-provider-aws/pkg/client"
 	mockaws "github.com/openshift/machine-api-provider-aws/pkg/client/mock"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -91,8 +92,10 @@ func TestMachineControllerWithDelayedExistSuccess(t *testing.T) {
 			AwsClientBuilder: awsClientBuilder,
 		}
 		actuator := NewActuator(params)
+		gate, err := testutils.NewDefaultMutableFeatureGate()
+		g.Expect(err).ToNot(HaveOccurred())
 
-		g.Expect(machinecontroller.AddWithActuator(mgr, actuator)).To(Succeed())
+		g.Expect(machinecontroller.AddWithActuator(mgr, actuator, gate)).To(Succeed())
 	}
 
 	var machine *machinev1beta1.Machine