session: add no register API for using TiDB as a library (pingcap#17513)

* domain,session: add NoRegister entry

* session: run fmt

* session: remove old NoRegister API

* config: add no register config

* config: add example to example config file.

* session: remove unused type

* *: rename NoRegister to SkipRegisterToDashboard

Co-authored-by: crazycs <crazycs520@gmail.com>

config/config.go

@@ -138,6 +138,8 @@ type Config struct {
 	Experimental Experimental `toml:"experimental" json:"experimental"`
 	// EnableCollectExecutionInfo enables the TiDB to collect execution info.
 	EnableCollectExecutionInfo bool `toml:"enable-collect-execution-info" json:"enable-collect-execution-info"`
+	// SkipRegisterToDashboard tells TiDB don't register itself to the dashboard.
+	SkipRegisterToDashboard bool `toml:"skip-register-to-dashboard" json:"skip-register-to-dashboard"`
 	// EnableTelemetry enables the usage data report to PingCAP.
 	EnableTelemetry bool `toml:"enable-telemetry" json:"enable-telemetry"`
 }

config/config.toml.example

@@ -106,6 +106,11 @@ max-server-connections = 0
 # Whether new collations are enabled, as indicated by its name, this configuration entry take effect ONLY when a TiDB cluster bootstraps for the first time.
 new_collations_enabled_on_first_bootstrap = false
 
+# Don't register information of this TiDB to etcd, so this instance of TiDB won't appear in the services like dashboard.
+# This option is useful when you want to embed TiDB into your service(i.e. use TiDB as a library).
+# *If you want to start a TiDB service, NEVER enable this.*
+skip-register-to-dashboard = false
+
 # When enabled, usage data (for example, instance versions) will be reported to PingCAP periodically for user experience analytics.
 # If this config is set to `false` on all TiDB servers, telemetry will be always disabled regardless of the value of the global variable `tidb_enable_telemetry`.
 # See PingCAP privacy policy for details: https://pingcap.com/en/privacy-policy/

config/config_test.go

@@ -189,6 +189,7 @@ repair-mode = true
 max-server-connections = 200
 mem-quota-query = 10000
 max-index-length = 3080
+skip-register-to-dashboard = true
 [performance]
 txn-total-size-limit=2000
 [tikv-client]
@@ -247,6 +248,7 @@ engines = ["tiflash"]
 	c.Assert(conf.Experimental.AllowAutoRandom, IsTrue)
 	c.Assert(conf.IsolationRead.Engines, DeepEquals, []string{"tiflash"})
 	c.Assert(conf.MaxIndexLength, Equals, 3080)
+	c.Assert(conf.SkipRegisterToDashboard, Equals, true)
 
 	_, err = f.WriteString(`
 [log.file]

domain/domain.go

@@ -713,11 +713,12 @@ func (do *Domain) Init(ddlLease time.Duration, sysFactory func(*Domain) (pools.R
 		}
 	})
 
+	skipRegisterToDashboard := config.GetGlobalConfig().SkipRegisterToDashboard
 	err = do.ddl.SchemaSyncer().Init(ctx)
 	if err != nil {
 		return err
 	}
-	do.info, err = infosync.GlobalInfoSyncerInit(ctx, do.ddl.GetID(), do.etcdClient)
+	do.info, err = infosync.GlobalInfoSyncerInit(ctx, do.ddl.GetID(), do.etcdClient, skipRegisterToDashboard)
 	if err != nil {
 		return err
 	}
@@ -739,8 +740,10 @@ func (do *Domain) Init(ddlLease time.Duration, sysFactory func(*Domain) (pools.R
 	do.wg.Add(1)
 	go do.infoSyncerKeeper()
 
-	do.wg.Add(1)
-	go do.topologySyncerKeeper()
+	if !skipRegisterToDashboard {
+		do.wg.Add(1)
+		go do.topologySyncerKeeper()
+	}
 
 	return nil
 }

domain/infosync/info.go

@@ -128,14 +128,14 @@ func setGlobalInfoSyncer(is *InfoSyncer) {
 }
 
 // GlobalInfoSyncerInit return a new InfoSyncer. It is exported for testing.
-func GlobalInfoSyncerInit(ctx context.Context, id string, etcdCli *clientv3.Client) (*InfoSyncer, error) {
+func GlobalInfoSyncerInit(ctx context.Context, id string, etcdCli *clientv3.Client, skipRegisterToDashBoard bool) (*InfoSyncer, error) {
 	is := &InfoSyncer{
 		etcdCli:        etcdCli,
 		info:           getServerInfo(id),
 		serverInfoPath: fmt.Sprintf("%s/%s", ServerInformationPath, id),
 		minStartTSPath: fmt.Sprintf("%s/%s", ServerMinStartTSPath, id),
 	}
-	err := is.init(ctx)
+	err := is.init(ctx, skipRegisterToDashBoard)
 	if err != nil {
 		return nil, err
 	}
@@ -144,11 +144,14 @@ func GlobalInfoSyncerInit(ctx context.Context, id string, etcdCli *clientv3.Clie
 }
 
 // Init creates a new etcd session and stores server info to etcd.
-func (is *InfoSyncer) init(ctx context.Context) error {
+func (is *InfoSyncer) init(ctx context.Context, skipRegisterToDashboard bool) error {
 	err := is.newSessionAndStoreServerInfo(ctx, owner.NewSessionDefaultRetryCnt)
 	if err != nil {
 		return err
 	}
+	if skipRegisterToDashboard {
+		return nil
+	}
 	return is.newTopologySessionAndStoreServerInfo(ctx, owner.NewSessionDefaultRetryCnt)
 }
 

domain/infosync/info_test.go

@@ -86,7 +86,7 @@ func TestTopology(t *testing.T) {
 	failpoint.Enable("github.com/pingcap/tidb/domain/infosync/mockServerInfo", "return(true)")
 	defer failpoint.Disable("github.com/pingcap/tidb/domain/infosync/mockServerInfo")
 
-	info, err := GlobalInfoSyncerInit(ctx, currentID, cli)
+	info, err := GlobalInfoSyncerInit(ctx, currentID, cli, false)
 	if err != nil {
 		t.Fatal(err)
 	}