mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-12-20 20:10:22 +00:00
365 lines
11 KiB
Go
365 lines
11 KiB
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/apimachinery/pkg/util/naming"
|
|
"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"
|
|
|
|
// allBetaGate is a global toggle for beta features. Per-feature key
|
|
// values override the default set by allBetaGate. Examples:
|
|
// AllBeta=false,NewFeature=true will result in NewFeature=true
|
|
// AllBeta=true,NewFeature=false will result in NewFeature=false
|
|
allBetaGate Feature = "AllBeta"
|
|
)
|
|
|
|
var (
|
|
// The generic features.
|
|
defaultFeatures = map[Feature]FeatureSpec{
|
|
allAlphaGate: {Default: false, PreRelease: Alpha},
|
|
allBetaGate: {Default: false, PreRelease: Beta},
|
|
}
|
|
|
|
// Special handling for a few gates.
|
|
specialFeatures = map[Feature]func(known map[Feature]FeatureSpec, enabled map[Feature]bool, val bool){
|
|
allAlphaGate: setUnsetAlphaGates,
|
|
allBetaGate: setUnsetBetaGates,
|
|
}
|
|
)
|
|
|
|
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 {
|
|
featureGateName string
|
|
|
|
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
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
func setUnsetBetaGates(known map[Feature]FeatureSpec, enabled map[Feature]bool, val bool) {
|
|
for k, v := range known {
|
|
if v.PreRelease == Beta {
|
|
if _, found := enabled[k]; !found {
|
|
enabled[k] = val
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Set, String, and Type implement pflag.Value
|
|
var _ pflag.Value = &featureGate{}
|
|
|
|
// internalPackages are packages that ignored when creating a name for featureGates. These packages are in the common
|
|
// call chains, so they'd be unhelpful as names.
|
|
var internalPackages = []string{"k8s.io/component-base/featuregate/feature_gate.go"}
|
|
|
|
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{
|
|
featureGateName: naming.GetNameFromCallsite(internalPackages...),
|
|
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. If the key is not known, this call will panic.
|
|
func (f *featureGate) Enabled(key Feature) bool {
|
|
if v, ok := f.enabled.Load().(map[Feature]bool)[key]; ok {
|
|
return v
|
|
}
|
|
if v, ok := f.known.Load().(map[Feature]FeatureSpec)[key]; ok {
|
|
return v.Default
|
|
}
|
|
|
|
panic(fmt.Errorf("feature %q is not registered in FeatureGate %q", key, f.featureGateName))
|
|
}
|
|
|
|
// 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,
|
|
}
|
|
}
|