Add feature gating system (#911)

Co-authored-by: Ken Sipe <kensipe@gmail.com>

go.mod

@@ -32,7 +32,7 @@ require (
 	github.com/mitchellh/copystructure v1.0.0 // indirect
 	github.com/morikuni/aec v1.0.0 // indirect
 	github.com/onsi/ginkgo v1.10.1 // indirect
-	github.com/onsi/gomega v1.7.1
+	github.com/onsi/gomega v1.7.1 // indirect
 	github.com/opencontainers/image-spec v1.0.1 // indirect
 	github.com/pmezard/go-difflib v1.0.0
 	github.com/prometheus/client_golang v1.0.0 // indirect
@@ -56,6 +56,7 @@ require (
 	k8s.io/apimachinery v0.0.0-20191028221656-72ed19daf4bb
 	k8s.io/client-go v11.0.0+incompatible
 	k8s.io/code-generator v0.18.0-alpha.1.0.20191220033320-6b257a9d6f46
+	k8s.io/component-base v0.0.0-20191016111319-039242c015a9
 	k8s.io/kubectl v0.0.0-20191016120415-2ed914427d51
 	sigs.k8s.io/controller-runtime v0.4.0
 	sigs.k8s.io/controller-tools v0.2.4

pkg/feature/doc.go

@@ -0,0 +1,7 @@
+package feature
+
+/*
+
+Package feature implements feature gating for KUDO based on the Kubernetes feature gating packages.
+
+*/

pkg/feature/feature.go

@@ -0,0 +1,18 @@
+package feature
+
+import (
+	"k8s.io/apimachinery/pkg/util/runtime"
+	"k8s.io/component-base/featuregate"
+)
+
+var (
+	DefaultMutableFeatureGate featuregate.MutableFeatureGate = featuregate.NewFeatureGate()
+
+	DefaultFeatureGate featuregate.FeatureGate = DefaultMutableFeatureGate
+)
+
+func init() {
+	runtime.Must(DefaultMutableFeatureGate.Add(defaultKUDOFeatureGates))
+}
+
+var defaultKUDOFeatureGates = map[featuregate.Feature]featuregate.FeatureSpec{}