HACK, UNTESTED: suppert external gate providers

Author: thockin

gate_example.go

@@ -0,0 +1,43 @@
+package main
+
+import (
+	"fmt"
+
+	"github.com/spf13/pflag"
+	"k8s.io/utils/feature"
+)
+
+var (
+	libGates = &feature.GateSet{}
+	f1       = libGates.Add(&feature.Gate{
+		Name:    "Feature1",
+		Default: false,
+		Release: feature.Alpha,
+	})
+	f2 = libGates.Add(&feature.Gate{
+		Name:    "Feature2",
+		Default: true,
+		Release: feature.Beta,
+	})
+	f3 = libGates.Add(&feature.Gate{
+		Name:          "Feature3",
+		Default:       true,
+		Release:       feature.GA,
+		LockToDefault: true,
+	})
+	f4 = &feature.Gate{
+		Name:    "Feature4",
+		Default: true,
+		Release: feature.Beta,
+	}
+)
+
+func main() {
+	libGates.EnablePFlagControl("gates", pflag.CommandLine)
+	libGates.EnableEnvControl("GATE_")
+	pflag.Parse()
+	fmt.Println(feature.Enabled(f1))
+	fmt.Println(feature.Enabled(f2))
+	fmt.Println(feature.Enabled(f3))
+	fmt.Println(feature.Enabled(f4))
+}

staging/src/k8s.io/apiserver/pkg/server/options/server_run_options.go

@@ -340,5 +340,6 @@ func (s *ServerRunOptions) AddUniversalFlags(fs *pflag.FlagSet) {
 		"This option, if set, represents the maximum amount of grace period the apiserver will wait "+
 		"for active watch request(s) to drain during the graceful server shutdown window.")
 
-	s.FeatureGates.AddFlags("new-feature-gates", fs)
+	s.FeatureGates.EnableFlagControl("new-feature-gates", fs)
+	s.FeatureGates.EnableEnvControl("KUBE_FEATURE_")
 }