move generic feature gate code from k8s.io/apiserver to k8s.io/component-base

hack/.golint_failures

@@ -500,7 +500,6 @@ staging/src/k8s.io/apiserver/pkg/storage/storagebackend
 staging/src/k8s.io/apiserver/pkg/storage/testing
 staging/src/k8s.io/apiserver/pkg/storage/tests
 staging/src/k8s.io/apiserver/pkg/storage/value
-staging/src/k8s.io/apiserver/pkg/util/feature
 staging/src/k8s.io/apiserver/pkg/util/proxy
 staging/src/k8s.io/apiserver/pkg/util/webhook
 staging/src/k8s.io/apiserver/pkg/util/wsstream
@@ -574,6 +573,7 @@ staging/src/k8s.io/code-generator/cmd/go-to-protobuf/protobuf
 staging/src/k8s.io/code-generator/cmd/lister-gen/generators
 staging/src/k8s.io/component-base/cli/flag
 staging/src/k8s.io/component-base/config/v1alpha1
+staging/src/k8s.io/component-base/featuregate
 staging/src/k8s.io/cri-api/pkg/apis/testing
 staging/src/k8s.io/kube-aggregator/pkg/apis/apiregistration/v1
 staging/src/k8s.io/kube-aggregator/pkg/apis/apiregistration/v1beta1

staging/src/k8s.io/apiserver/pkg/util/feature/BUILD

 package(default_visibility = ["//visibility:public"])
 
-load(
-    "@io_bazel_rules_go//go:def.bzl",
-    "go_library",
-    "go_test",
-)
-
-go_test(
-    name = "go_default_test",
-    srcs = ["feature_gate_test.go"],
-    embed = [":go_default_library"],
-    deps = [
-        "//vendor/github.com/spf13/pflag:go_default_library",
-        "//vendor/github.com/stretchr/testify/assert:go_default_library",
-    ],
-)
+load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
     srcs = ["feature_gate.go"],
     importmap = "k8s.io/kubernetes/vendor/k8s.io/apiserver/pkg/util/feature",
     importpath = "k8s.io/apiserver/pkg/util/feature",
-    deps = [
-        "//vendor/github.com/spf13/pflag:go_default_library",
-        "//vendor/k8s.io/klog:go_default_library",
-    ],
+    deps = ["//staging/src/k8s.io/component-base/featuregate:go_default_library"],
 )
 
 filegroup(
@@ -36,9 +19,6 @@ filegroup(
 
 filegroup(
     name = "all-srcs",
-    srcs = [
-        ":package-srcs",
-        "//staging/src/k8s.io/apiserver/pkg/util/feature/testing:all-srcs",
-    ],
+    srcs = [":package-srcs"],
     tags = ["automanaged"],
 )

staging/src/k8s.io/component-base/featuregate/BUILD

+load("@io_bazel_rules_go//go:def.bzl", "go_library", "go_test")
+
+go_library(
+    name = "go_default_library",
+    srcs = ["feature_gate.go"],
+    importmap = "k8s.io/kubernetes/vendor/k8s.io/component-base/featuregate",
+    importpath = "k8s.io/component-base/featuregate",
+    visibility = ["//visibility:public"],
+    deps = [
+        "//vendor/github.com/spf13/pflag:go_default_library",
+        "//vendor/k8s.io/klog:go_default_library",
+    ],
+)
+
+go_test(
+    name = "go_default_test",
+    srcs = ["feature_gate_test.go"],
+    embed = [":go_default_library"],
+    deps = [
+        "//vendor/github.com/spf13/pflag:go_default_library",
+        "//vendor/github.com/stretchr/testify/assert:go_default_library",
+    ],
+)
+
+filegroup(
+    name = "package-srcs",
+    srcs = glob(["**"]),
+    tags = ["automanaged"],
+    visibility = ["//visibility:private"],
+)
+
+filegroup(
+    name = "all-srcs",
+    srcs = [
+        ":package-srcs",
+        "//staging/src/k8s.io/component-base/featuregate/testing:all-srcs",
+    ],
+    tags = ["automanaged"],
+    visibility = ["//visibility:public"],
+)

staging/src/k8s.io/component-base/featuregate/feature_gate.go

+/*
+Copyright 2016 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 featuregate
+
+import (
+	"fmt"
+	"sort"
+	"strconv"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"github.com/spf13/pflag"
+	"k8s.io/klog"
+)
+
+type Feature string
+
+const (
+	flagName = "feature-gates"
+
+	// allAlphaGate is a global toggle for alpha features. Per-feature key
+	// values override the default set by allAlphaGate. Examples:
+	//   AllAlpha=false,NewFeature=true  will result in newFeature=true
+	//   AllAlpha=true,NewFeature=false  will result in newFeature=false
+	allAlphaGate Feature = "AllAlpha"
+)
+
+var (
+	// The generic features.
+	defaultFeatures = map[Feature]FeatureSpec{
+		allAlphaGate: {Default: false, PreRelease: Alpha},
+	}
+
+	// Special handling for a few gates.
+	specialFeatures = map[Feature]func(known map[Feature]FeatureSpec, enabled map[Feature]bool, val bool){
+		allAlphaGate: setUnsetAlphaGates,
+	}
+)
+
+type FeatureSpec struct {
+	// Default is the default enablement state for the feature
+	Default bool
+	// LockToDefault indicates that the feature is locked to its default and cannot be changed
+	LockToDefault bool
+	// PreRelease indicates the maturity level of the feature
+	PreRelease prerelease
+}
+
+type prerelease string
+
+const (
+	// Values for PreRelease.
+	Alpha = prerelease("ALPHA")
+	Beta  = prerelease("BETA")
+	GA    = prerelease("")
+
+	// Deprecated
+	Deprecated = prerelease("DEPRECATED")
+)
+
+// FeatureGate indicates whether a given feature is enabled or not
+type FeatureGate interface {
+	// Enabled returns true if the key is enabled.
+	Enabled(key Feature) bool
+	// KnownFeatures returns a slice of strings describing the FeatureGate's known features.
+	KnownFeatures() []string
+	// DeepCopy returns a deep copy of the FeatureGate object, such that gates can be
+	// set on the copy without mutating the original. This is useful for validating
+	// config against potential feature gate changes before committing those changes.
+	DeepCopy() MutableFeatureGate
+}
+
+// MutableFeatureGate parses and stores flag gates for known features from
+// a string like feature1=true,feature2=false,...
+type MutableFeatureGate interface {
+	FeatureGate
+
+	// AddFlag adds a flag for setting global feature gates to the specified FlagSet.
+	AddFlag(fs *pflag.FlagSet)
+	// Set parses and stores flag gates for known features
+	// from a string like feature1=true,feature2=false,...
+	Set(value string) error
+	// SetFromMap stores flag gates for known features from a map[string]bool or returns an error
+	SetFromMap(m map[string]bool) error
+	// Add adds features to the featureGate.
+	Add(features map[Feature]FeatureSpec) error
+}
+
+// featureGate implements FeatureGate as well as pflag.Value for flag parsing.
+type featureGate struct {
+	special map[Feature]func(map[Feature]FeatureSpec, map[Feature]bool, bool)
+
+	// lock guards writes to known, enabled, and reads/writes of closed
+	lock sync.Mutex
+	// known holds a map[Feature]FeatureSpec
+	known *atomic.Value
+	// enabled holds a map[Feature]bool
+	enabled *atomic.Value
+	// closed is set to true when AddFlag is called, and prevents subsequent calls to Add
+	closed bool
+}
+
+func setUnsetAlphaGates(known map[Feature]FeatureSpec, enabled map[Feature]bool, val bool) {
+	for k, v := range known {
+		if v.PreRelease == Alpha {
+			if _, found := enabled[k]; !found {
+				enabled[k] = val
+			}
+		}
+	}
+}
+
+// Set, String, and Type implement pflag.Value
+var _ pflag.Value = &featureGate{}
+
+func NewFeatureGate() *featureGate {
+	known := map[Feature]FeatureSpec{}
+	for k, v := range defaultFeatures {
+		known[k] = v
+	}
+
+	knownValue := &atomic.Value{}
+	knownValue.Store(known)
+
+	enabled := map[Feature]bool{}
+	enabledValue := &atomic.Value{}
+	enabledValue.Store(enabled)
+
+	f := &featureGate{
+		known:   knownValue,
+		special: specialFeatures,
+		enabled: enabledValue,
+	}
+	return f
+}
+
+// Set parses a string of the form "key1=value1,key2=value2,..." into a
+// map[string]bool of known keys or returns an error.
+func (f *featureGate) Set(value string) error {
+	m := make(map[string]bool)
+	for _, s := range strings.Split(value, ",") {
+		if len(s) == 0 {
+			continue
+		}
+		arr := strings.SplitN(s, "=", 2)
+		k := strings.TrimSpace(arr[0])
+		if len(arr) != 2 {
+			return fmt.Errorf("missing bool value for %s", k)
+		}
+		v := strings.TrimSpace(arr[1])
+		boolValue, err := strconv.ParseBool(v)
+		if err != nil {
+			return fmt.Errorf("invalid value of %s=%s, err: %v", k, v, err)
+		}
+		m[k] = boolValue
+	}
+	return f.SetFromMap(m)
+}
+
+// SetFromMap stores flag gates for known features from a map[string]bool or returns an error
+func (f *featureGate) SetFromMap(m map[string]bool) error {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	// Copy existing state
+	known := map[Feature]FeatureSpec{}
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		known[k] = v
+	}
+	enabled := map[Feature]bool{}
+	for k, v := range f.enabled.Load().(map[Feature]bool) {
+		enabled[k] = v
+	}
+
+	for k, v := range m {
+		k := Feature(k)
+		featureSpec, ok := known[k]
+		if !ok {
+			return fmt.Errorf("unrecognized feature gate: %s", k)
+		}
+		if featureSpec.LockToDefault && featureSpec.Default != v {
+			return fmt.Errorf("cannot set feature gate %v to %v, feature is locked to %v", k, v, featureSpec.Default)
+		}
+		enabled[k] = v
+		// Handle "special" features like "all alpha gates"
+		if fn, found := f.special[k]; found {
+			fn(known, enabled, v)
+		}
+
+		if featureSpec.PreRelease == Deprecated {
+			klog.Warningf("Setting deprecated feature gate %s=%t. It will be removed in a future release.", k, v)
+		} else if featureSpec.PreRelease == GA {
+			klog.Warningf("Setting GA feature gate %s=%t. It will be removed in a future release.", k, v)
+		}
+	}
+
+	// Persist changes
+	f.known.Store(known)
+	f.enabled.Store(enabled)
+
+	klog.V(1).Infof("feature gates: %v", f.enabled)
+	return nil
+}
+
+// String returns a string containing all enabled feature gates, formatted as "key1=value1,key2=value2,...".
+func (f *featureGate) String() string {
+	pairs := []string{}
+	for k, v := range f.enabled.Load().(map[Feature]bool) {
+		pairs = append(pairs, fmt.Sprintf("%s=%t", k, v))
+	}
+	sort.Strings(pairs)
+	return strings.Join(pairs, ",")
+}
+
+func (f *featureGate) Type() string {
+	return "mapStringBool"
+}
+
+// Add adds features to the featureGate.
+func (f *featureGate) Add(features map[Feature]FeatureSpec) error {
+	f.lock.Lock()
+	defer f.lock.Unlock()
+
+	if f.closed {
+		return fmt.Errorf("cannot add a feature gate after adding it to the flag set")
+	}
+
+	// Copy existing state
+	known := map[Feature]FeatureSpec{}
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		known[k] = v
+	}
+
+	for name, spec := range features {
+		if existingSpec, found := known[name]; found {
+			if existingSpec == spec {
+				continue
+			}
+			return fmt.Errorf("feature gate %q with different spec already exists: %v", name, existingSpec)
+		}
+
+		known[name] = spec
+	}
+
+	// Persist updated state
+	f.known.Store(known)
+
+	return nil
+}
+
+// Enabled returns true if the key is enabled.
+func (f *featureGate) Enabled(key Feature) bool {
+	if v, ok := f.enabled.Load().(map[Feature]bool)[key]; ok {
+		return v
+	}
+	return f.known.Load().(map[Feature]FeatureSpec)[key].Default
+}
+
+// AddFlag adds a flag for setting global feature gates to the specified FlagSet.
+func (f *featureGate) AddFlag(fs *pflag.FlagSet) {
+	f.lock.Lock()
+	// TODO(mtaufen): Shouldn't we just close it on the first Set/SetFromMap instead?
+	// Not all components expose a feature gates flag using this AddFlag method, and
+	// in the future, all components will completely stop exposing a feature gates flag,
+	// in favor of componentconfig.
+	f.closed = true
+	f.lock.Unlock()
+
+	known := f.KnownFeatures()
+	fs.Var(f, flagName, ""+
+		"A set of key=value pairs that describe feature gates for alpha/experimental features. "+
+		"Options are:\n"+strings.Join(known, "\n"))
+}
+
+// KnownFeatures returns a slice of strings describing the FeatureGate's known features.
+// Deprecated and GA features are hidden from the list.
+func (f *featureGate) KnownFeatures() []string {
+	var known []string
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		if v.PreRelease == GA || v.PreRelease == Deprecated {
+			continue
+		}
+		known = append(known, fmt.Sprintf("%s=true|false (%s - default=%t)", k, v.PreRelease, v.Default))
+	}
+	sort.Strings(known)
+	return known
+}
+
+// DeepCopy returns a deep copy of the FeatureGate object, such that gates can be
+// set on the copy without mutating the original. This is useful for validating
+// config against potential feature gate changes before committing those changes.
+func (f *featureGate) DeepCopy() MutableFeatureGate {
+	// Copy existing state.
+	known := map[Feature]FeatureSpec{}
+	for k, v := range f.known.Load().(map[Feature]FeatureSpec) {
+		known[k] = v
+	}
+	enabled := map[Feature]bool{}
+	for k, v := range f.enabled.Load().(map[Feature]bool) {
+		enabled[k] = v
+	}
+
+	// Store copied state in new atomics.
+	knownValue := &atomic.Value{}
+	knownValue.Store(known)
+	enabledValue := &atomic.Value{}
+	enabledValue.Store(enabled)
+
+	// Construct a new featureGate around the copied state.
+	// Note that specialFeatures is treated as immutable by convention,
+	// and we maintain the value of f.closed across the copy.
+	return &featureGate{
+		special: specialFeatures,
+		known:   knownValue,
+		enabled: enabledValue,
+		closed:  f.closed,
+	}
+}

staging/src/k8s.io/apiserver/pkg/util/feature/feature_gate_test.go → staging/src/k8s.io/component-base/featuregate/feature_gate_test.go

@@ -14,7 +14,7 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 
-package feature
+package featuregate
 
 import (
 	"fmt"

staging/src/k8s.io/apiserver/pkg/util/feature/testing/BUILD → staging/src/k8s.io/component-base/featuregate/testing/BUILD

@@ -2,11 +2,11 @@ load("@io_bazel_rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "go_default_library",
-    srcs = ["feature_gate_testing.go"],
-    importmap = "k8s.io/kubernetes/vendor/k8s.io/apiserver/pkg/util/feature/testing",
-    importpath = "k8s.io/apiserver/pkg/util/feature/testing",
+    srcs = ["feature_gate.go"],
+    importmap = "k8s.io/kubernetes/vendor/k8s.io/component-base/featuregate/testing",
+    importpath = "k8s.io/component-base/featuregate/testing",
     visibility = ["//visibility:public"],
-    deps = ["//staging/src/k8s.io/apiserver/pkg/util/feature:go_default_library"],
+    deps = ["//staging/src/k8s.io/component-base/featuregate:go_default_library"],
 )
 
 filegroup(

staging/src/k8s.io/apiserver/pkg/util/feature/testing/feature_gate_testing.go → staging/src/k8s.io/component-base/featuregate/testing/feature_gate.go

@@ -20,7 +20,7 @@ import (
 	"fmt"
 	"testing"
 
-	"k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/component-base/featuregate"
 )
 
 // SetFeatureGateDuringTest sets the specified gate to the specified value, and returns a function that restores the original value.
@@ -28,16 +28,16 @@ import (
 //
 // Example use:
 //
-// defer utilfeaturetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.<FeatureName>, true)()
-func SetFeatureGateDuringTest(tb testing.TB, gate feature.FeatureGate, f feature.Feature, value bool) func() {
+// defer featuregatetesting.SetFeatureGateDuringTest(t, utilfeature.DefaultFeatureGate, features.<FeatureName>, true)()
+func SetFeatureGateDuringTest(tb testing.TB, gate featuregate.FeatureGate, f featuregate.Feature, value bool) func() {
 	originalValue := gate.Enabled(f)
 
-	if err := gate.(feature.MutableFeatureGate).Set(fmt.Sprintf("%s=%v", f, value)); err != nil {
+	if err := gate.(featuregate.MutableFeatureGate).Set(fmt.Sprintf("%s=%v", f, value)); err != nil {
 		tb.Errorf("error setting %s=%v: %v", f, value, err)
 	}
 
 	return func() {
-		if err := gate.(feature.MutableFeatureGate).Set(fmt.Sprintf("%s=%v", f, originalValue)); err != nil {
+		if err := gate.(featuregate.MutableFeatureGate).Set(fmt.Sprintf("%s=%v", f, originalValue)); err != nil {
 			tb.Errorf("error restoring %s=%v: %v", f, originalValue, err)
 		}
 	}