etcdserver: add --max-request-bytes flag

embed/config.go

@@ -37,9 +37,10 @@ const (
 	ClusterStateFlagNew      = "new"
 	ClusterStateFlagExisting = "existing"
 
-	DefaultName         = "default"
-	DefaultMaxSnapshots = 5
-	DefaultMaxWALs      = 5
+	DefaultName            = "default"
+	DefaultMaxSnapshots    = 5
+	DefaultMaxWALs         = 5
+	DefaultMaxRequestBytes = 1.5 * 1024 * 1024
 
 	DefaultListenPeerURLs   = "http://localhost:2380"
 	DefaultListenClientURLs = "http://localhost:2379"
@@ -85,6 +86,7 @@ type Config struct {
 	TickMs            uint  `json:"heartbeat-interval"`
 	ElectionMs        uint  `json:"election-timeout"`
 	QuotaBackendBytes int64 `json:"quota-backend-bytes"`
+	MaxRequestBytes   uint  `json:"max-request-bytes"`
 
 	// clustering
 
@@ -172,6 +174,7 @@ func NewConfig() *Config {
 		MaxWalFiles:         DefaultMaxWALs,
 		Name:                DefaultName,
 		SnapCount:           etcdserver.DefaultSnapCount,
+		MaxRequestBytes:     DefaultMaxRequestBytes,
 		TickMs:              100,
 		ElectionMs:          1000,
 		LPUrls:              []url.URL{*lpurl},

embed/etcd.go

@@ -139,6 +139,7 @@ func StartEtcd(inCfg *Config) (e *Etcd, err error) {
 		ElectionTicks:           cfg.ElectionTicks(),
 		AutoCompactionRetention: cfg.AutoCompactionRetention,
 		QuotaBackendBytes:       cfg.QuotaBackendBytes,
+		MaxRequestBytes:         cfg.MaxRequestBytes,
 		StrictReconfigCheck:     cfg.StrictReconfigCheck,
 		ClientCertAuthEnabled:   cfg.ClientTLSInfo.ClientCertAuth,
 		AuthToken:               cfg.AuthToken,

etcdmain/config.go

@@ -138,6 +138,7 @@ func newConfig() *config {
 	fs.UintVar(&cfg.TickMs, "heartbeat-interval", cfg.TickMs, "Time (in milliseconds) of a heartbeat interval.")
 	fs.UintVar(&cfg.ElectionMs, "election-timeout", cfg.ElectionMs, "Time (in milliseconds) for an election to timeout.")
 	fs.Int64Var(&cfg.QuotaBackendBytes, "quota-backend-bytes", cfg.QuotaBackendBytes, "Raise alarms when backend size exceeds the given quota. 0 means use the default quota.")
+	fs.UintVar(&cfg.MaxRequestBytes, "max-request-bytes", cfg.MaxRequestBytes, "Maximum client request size in bytes the server will accept.")
 
 	// clustering
 	fs.Var(flags.NewURLsValue(embed.DefaultInitialAdvertisePeerURLs), "initial-advertise-peer-urls", "List of this member's peer URLs to advertise to the rest of the cluster.")

etcdmain/help.go

@@ -66,6 +66,8 @@ member flags:
 		comma-separated whitelist of origins for CORS (cross-origin resource sharing).
 	--quota-backend-bytes '0'
 		raise alarms when backend size exceeds the given quota (0 defaults to low space quota).
+	--max-request-bytes '1572864'
+		maximum client request size in bytes the server will accept.
 
 clustering flags:
 

etcdserver/config.go

@@ -55,6 +55,9 @@ type ServerConfig struct {
 	AutoCompactionRetention int
 	QuotaBackendBytes       int64
 
+	//MaxRequestBytes is the maximum request size to send over raft.
+	MaxRequestBytes uint
+
 	StrictReconfigCheck bool
 
 	// ClientCertAuthEnabled is true when cert has been signed by the client CA.

etcdserver/server.go

@@ -83,6 +83,8 @@ const (
 
 	// maxPendingRevokes is the maximum number of outstanding expired lease revocations.
 	maxPendingRevokes = 16
+
+	recommendedMaxRequestBytes = 10 * 1024 * 1024
 )
 
 var (
@@ -259,6 +261,10 @@ func NewServer(cfg *ServerConfig) (srv *EtcdServer, err error) {
 		cl *membership.RaftCluster
 	)
 
+	if cfg.MaxRequestBytes > recommendedMaxRequestBytes {
+		plog.Warningf("MaxRequestBytes %v exceeds maximum recommended size %v", cfg.MaxRequestBytes, recommendedMaxRequestBytes)
+	}
+
 	if terr := fileutil.TouchDirAll(cfg.DataDir); terr != nil {
 		return nil, fmt.Errorf("cannot access data directory: %v", terr)
 	}

etcdserver/v3_server.go

@@ -31,12 +31,6 @@ import (
 )
 
 const (
-	// the max request size that raft accepts.
-	// TODO: make this a flag? But we probably do not want to
-	// accept large request which might block raft stream. User
-	// specify a large value might end up with shooting in the foot.
-	maxRequestBytes = 1.5 * 1024 * 1024
-
 	// In the health case, there might be a small gap (10s of entries) between
 	// the applied index and committed index.
 	// However, if the committed entries are very heavy to apply, the gap might grow.
@@ -605,7 +599,7 @@ func (s *EtcdServer) processInternalRaftRequestOnce(ctx context.Context, r pb.In
 		return nil, err
 	}
 
-	if len(data) > maxRequestBytes {
+	if len(data) > int(s.Cfg.MaxRequestBytes) {
 		return nil, ErrRequestTooLarge
 	}