feat: add support for feature gates

Signed-off-by: Evan Freed <evan.freed@protonmail.ch>

feature/feature.go

@@ -0,0 +1,40 @@
+/*
+Copyright 2022 The Kubernetes 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 feature implements feature functionality.
+package feature
+
+import (
+	"k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/component-base/featuregate"
+)
+
+const (
+// Every capg-specific feature gate should add method here following this template:
+//
+// // owner: @username
+// // alpha: v1.X
+// MyFeature featuregate.Feature = "MyFeature".
+
+)
+
+func init() {
+	runtime.Must(MutableGates.Add(defaultCAPGFeatureGates))
+}
+
+// defaultCAPGFeatureGates consists of all known capg-specific feature keys.
+// To add a new feature, define a key for it above and add it here.
+var defaultCAPGFeatureGates = map[featuregate.Feature]featuregate.FeatureSpec{
+	// Every feature should be initiated here:
+
+}

feature/gates.go

@@ -0,0 +1,31 @@
+/*
+Copyright 2022 The Kubernetes 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 feature
+
+import (
+	"k8s.io/component-base/featuregate"
+	"sigs.k8s.io/cluster-api/feature"
+)
+
+var (
+	// MutableGates is a mutable version of DefaultFeatureGate.
+	// Only top-level commands/options setup and the k8s.io/component-base/featuregate/testing package should make use of this.
+	// Tests that need to modify featuregate gates for the duration of their test should use:
+	//   defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.<FeatureName>, <value>)()
+	MutableGates featuregate.MutableFeatureGate = feature.MutableGates
+
+	// Gates is a shared global FeatureGate.
+	// Top-level commands/options setup that needs to modify this featuregate gate should use DefaultMutableFeatureGate.
+	Gates featuregate.FeatureGate = MutableGates
+)

go.mod

@@ -15,6 +15,7 @@ require (
 	k8s.io/api v0.24.4
 	k8s.io/apimachinery v0.24.4
 	k8s.io/client-go v0.24.4
+	k8s.io/component-base v0.24.2
 	k8s.io/klog/v2 v2.70.1
 	k8s.io/utils v0.0.0-20220210201930-3a6ce19ff2f9
 	sigs.k8s.io/cluster-api v1.2.1
@@ -121,7 +122,6 @@ require (
 	k8s.io/apiextensions-apiserver v0.24.2 // indirect
 	k8s.io/apiserver v0.24.2 // indirect
 	k8s.io/cluster-bootstrap v0.24.0 // indirect
-	k8s.io/component-base v0.24.2 // indirect
 	k8s.io/kube-openapi v0.0.0-20220328201542-3ee0da9b0b42 // indirect
 	sigs.k8s.io/json v0.0.0-20211208200746-9f7c6b3444d2 // indirect
 	sigs.k8s.io/kind v0.14.0 // indirect

main.go

@@ -36,6 +36,7 @@ import (
 	infrav1alpha4 "sigs.k8s.io/cluster-api-provider-gcp/api/v1alpha4"
 	infrav1beta1 "sigs.k8s.io/cluster-api-provider-gcp/api/v1beta1"
 	"sigs.k8s.io/cluster-api-provider-gcp/controllers"
+	"sigs.k8s.io/cluster-api-provider-gcp/feature"
 	"sigs.k8s.io/cluster-api-provider-gcp/util/reconciler"
 	"sigs.k8s.io/cluster-api-provider-gcp/version"
 	clusterv1 "sigs.k8s.io/cluster-api/api/v1beta1"
@@ -295,4 +296,6 @@ func initFlags(fs *pflag.FlagSet) {
 		reconciler.DefaultLoopTimeout,
 		"The maximum duration a reconcile loop can run (e.g. 90m)",
 	)
+
+	feature.MutableGates.AddFlag(fs)
 }