Enable --pre-vote=true by default in 3.5.

CHANGELOG-3.5.md

@@ -66,6 +66,7 @@ See [code changes](https://github.com/etcd-io/etcd/compare/v3.4.0...v3.5.0) and
 - ClientV3 supports [grpc resolver API](https://github.com/etcd-io/etcd/blob/master/client/v3/naming/resolver/resolver.go).
   - Endpoints can be managed using [endpoints.Manager](https://github.com/etcd-io/etcd/blob/master/client/v3/naming/endpoints/endpoints.go)
   - Previously supported [GRPCResolver was decomissioned](https://github.com/etcd-io/etcd/pull/12675). Use [resolver](https://github.com/etcd-io/etcd/blob/master/client/v3/naming/resolver/resolver.go) instead.
+- Turned on [--pre-vote by default](https://github.com/etcd-io/etcd/pull/). Should prevent disrupting RAFT leader by an individual member. 
 
 ### `etcdctl`
 

server/embed/config.go

@@ -239,7 +239,6 @@ type Config struct {
 	// If enabled, Raft runs an additional election phase
 	// to check whether it would get enough votes to win
 	// an election, thus minimizing disruptions.
-	// TODO: enable by default in 3.5.
 	PreVote bool `json:"pre-vote"`
 
 	CORS map[string]struct{}
@@ -436,7 +435,7 @@ func NewConfig() *Config {
 		BcryptCost:   uint(bcrypt.DefaultCost),
 		AuthTokenTTL: 300,
 
-		PreVote: false, // TODO: enable by default in v3.5
+		PreVote: true,
 
 		loggerMu:          new(sync.RWMutex),
 		logger:            nil,

server/etcdmain/help.go

@@ -116,7 +116,7 @@ Clustering:
     Suffix to the dns srv name queried when bootstrapping.
   --strict-reconfig-check '` + strconv.FormatBool(embed.DefaultStrictReconfigCheck) + `'
     Reject reconfiguration requests that would cause quorum loss.
-  --pre-vote 'false'
+  --pre-vote 'true'
     Enable to run an additional Raft election phase.
   --auto-compaction-retention '0'
     Auto compaction retention length. 0 means disable auto compaction.