featuregate: adds EtcdServer.FeatureEnabled interface.

The interface can be used throughout the etcd server binary to check if
the feature is enabled or not.

Note that this commit also copies necessary FeatureGate interface from
k8s component-base.

Signed-off-by: Baek <[email protected]>

go.mod

@@ -1,6 +1,6 @@
 module go.etcd.io/etcd/v3
 
-go 1.22
+go 1.22.0
 
 toolchain go1.22.4
 
@@ -43,6 +43,7 @@ require (
 require (
 	github.com/VividCortex/ewma v1.2.0 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect
+	github.com/blang/semver/v4 v4.0.0 // indirect
 	github.com/cenkalti/backoff/v4 v4.3.0 // indirect
 	github.com/cespare/xxhash/v2 v2.2.0 // indirect
 	github.com/coreos/go-systemd/v22 v22.5.0 // indirect
@@ -94,7 +95,11 @@ require (
 	google.golang.org/genproto/googleapis/api v0.0.0-20240520151616-dc85e6b867a5 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20240520151616-dc85e6b867a5 // indirect
 	gopkg.in/natefinch/lumberjack.v2 v2.2.1 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
+	k8s.io/apimachinery v0.30.1 // indirect
+	k8s.io/component-base v0.30.1 // indirect
+	k8s.io/klog/v2 v2.120.1 // indirect
 	sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd // indirect
 	sigs.k8s.io/yaml v1.4.0 // indirect
 )

go.sum

@@ -6,6 +6,8 @@ github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
 github.com/bgentry/speakeasy v0.1.0 h1:ByYyxL9InA1OWqxJqqp2A5pYHUrCiAL6K3J+LKSsQkY=
 github.com/bgentry/speakeasy v0.1.0/go.mod h1:+zsyZBPWlz7T6j88CTgSN5bM796AkVf0kBD4zp0CCIs=
+github.com/blang/semver/v4 v4.0.0 h1:1PFHFE6yCCTv8C1TeyNNarDzntLi7wMI5i/pzqYIsAM=
+github.com/blang/semver/v4 v4.0.0/go.mod h1:IbckMUScFkM3pff0VJDNKRiT6TG/YpiHIM2yvyW5YoQ=
 github.com/cenkalti/backoff/v4 v4.3.0 h1:MyRJ/UdXutAwSAT+s3wNd7MfTIcy71VQueUuFK343L8=
 github.com/cenkalti/backoff/v4 v4.3.0/go.mod h1:Y3VNntkOUPxTVeUxJ/G5vcM//AlwfmyYozVcomhLiZE=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
@@ -245,11 +247,21 @@ gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c/go.mod h1:JHkPIbrfpd72SG/EV
 gopkg.in/natefinch/lumberjack.v2 v2.2.1 h1:bBRl1b0OH9s/DuPhuXpNl+VtCaJXFZ5/uEFST95x9zc=
 gopkg.in/natefinch/lumberjack.v2 v2.2.1/go.mod h1:YD8tP3GAjkrDg1eZH7EGmyESg/lsYskCTPBJVb9jqSc=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
 gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 honnef.co/go/tools v0.0.0-20190102054323-c2f93a96b099/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
 honnef.co/go/tools v0.0.0-20190523083050-ea95bdfd59fc/go.mod h1:rf3lG4BRIbNafJWhAfAdb/ePZxsR/4RtNHQocxwk9r4=
+k8s.io/apimachinery v0.30.1 h1:ZQStsEfo4n65yAdlGTfP/uSHMQSoYzU/oeEbkmF7P2U=
+k8s.io/apimachinery v0.30.1/go.mod h1:iexa2somDaxdnj7bha06bhb43Zpa6eWH8N8dbqVjTUc=
+k8s.io/component-base v0.30.1 h1:bvAtlPh1UrdaZL20D9+sWxsJljMi0QZ3Lmw+kmZAaxQ=
+k8s.io/component-base v0.30.1/go.mod h1:e/X9kDiOebwlI41AvBHuWdqFriSRrX50CdwA9TFaHLI=
+k8s.io/klog/v2 v2.120.1 h1:QXU6cPEOIslTGvZaXvFWiP9VKyeet3sawzTOvdXb4Vw=
+k8s.io/klog/v2 v2.120.1/go.mod h1:3Jpz1GvMt720eyJH1ckRHK1EDfpxISzJ7I9OYgaDtPE=
+k8s.io/utils v0.0.0-20230726121419-3b25d923346b h1:sgn3ZU783SCgtaSJjpcVVlRqd6GSnlTLKgpAAttJvpI=
+k8s.io/utils v0.0.0-20230726121419-3b25d923346b/go.mod h1:OLgZIPagt7ERELqWJFomSt595RzquPNLL48iOWgYOg0=
 sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd h1:EDPBXCAspyGV4jQlpZSudPeMmr1bNJefnuqLsRAsHZo=
 sigs.k8s.io/json v0.0.0-20221116044647-bc3834ca7abd/go.mod h1:B8JuhiUyNFVKdsE8h686QcCxMaH6HrOAZj4vswFpcB0=
 sigs.k8s.io/yaml v1.4.0 h1:Mk1wCc2gy/F0THH0TAp1QYyJNzRm2KCLy3o5ASXVI5E=

server/config/config.go

@@ -24,6 +24,7 @@ import (
 
 	"go.opentelemetry.io/contrib/instrumentation/google.golang.org/grpc/otelgrpc"
 	"go.uber.org/zap"
+	"k8s.io/component-base/featuregate"
 
 	bolt "go.etcd.io/bbolt"
 	"go.etcd.io/etcd/client/pkg/v3/transport"
@@ -206,7 +207,7 @@ type ServerConfig struct {
 	// V2Deprecation defines a phase of v2store deprecation process.
 	V2Deprecation V2DeprecationEnum `json:"v2-deprecation"`
 
-  // ExperimentalLocalAddress is the local IP address to use when communicating with a peer.
+	// ExperimentalLocalAddress is the local IP address to use when communicating with a peer.
 	ExperimentalLocalAddress string `json:"experimental-local-address"`
 
 	// ServerFeatureGate is a server level feature gate

server/etcdserver/server.go

@@ -32,6 +32,7 @@ import (
 	humanize "github.com/dustin/go-humanize"
 	"github.com/prometheus/client_golang/prometheus"
 	"go.uber.org/zap"
+	"k8s.io/component-base/featuregate"
 
 	pb "go.etcd.io/etcd/api/v3/etcdserverpb"
 	"go.etcd.io/etcd/api/v3/membershippb"