fix(telemetry): start telemetry independently from the API server

CHANGELOG.md

@@ -89,6 +89,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (testutil/sims) [#12374](https://github.com/cosmos/cosmos-sdk/pull/12374) fix the non-determinstic behavior in simulations caused by `GenSignedMockTx` and check 
 empty coins slice before it is used to create `banktype.MsgSend`.
 * (x/auth/tx) [#12474](https://github.com/cosmos/cosmos-sdk/pull/12474) Remove condition in GetTxsEvent that disallowed multiple equal signs, which would break event queries with base64 strings (i.e. query by signature).
+* [#12448](https://github.com/cosmos/cosmos-sdk/pull/12448) Start telemetry independently from the API server.
 
 ## [v0.46.0-rc1](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.46.0-rc1) - 2022-05-23
 

server/api/server.go

@@ -90,16 +90,6 @@ func New(clientCtx client.Context, logger log.Logger) *Server {
 // non-blocking, so an external signal handler must be used.
 func (s *Server) Start(cfg config.Config) error {
 	s.mtx.Lock()
-	if cfg.Telemetry.Enabled {
-		m, err := telemetry.New(cfg.Telemetry)
-		if err != nil {
-			s.mtx.Unlock()
-			return err
-		}
-
-		s.metrics = m
-		s.registerMetrics()
-	}
 
 	tmCfg := tmrpcserver.DefaultConfig()
 	tmCfg.MaxOpenConnections = int(cfg.API.MaxOpenConnections)
@@ -114,18 +104,17 @@ func (s *Server) Start(cfg config.Config) error {
 	}
 
 	s.registerGRPCGatewayRoutes()
-
 	s.listener = listener
 	var h http.Handler = s.Router
 
+	s.mtx.Unlock()
+
 	if cfg.API.EnableUnsafeCORS {
 		allowAllCORS := handlers.CORS(handlers.AllowedHeaders([]string{"Content-Type"}))
-		s.mtx.Unlock()
 		return tmrpcserver.Serve(s.listener, allowAllCORS(h), s.logger, tmCfg)
 	}
 
 	s.logger.Info("starting API server...")
-	s.mtx.Unlock()
 	return tmrpcserver.Serve(s.listener, s.Router, s.logger, tmCfg)
 }
 
@@ -140,6 +129,13 @@ func (s *Server) registerGRPCGatewayRoutes() {
 	s.Router.PathPrefix("/").Handler(s.GRPCGatewayRouter)
 }
 
+func (s *Server) SetTelemetry(m *telemetry.Metrics) {
+	s.mtx.Lock()
+	s.metrics = m
+	s.registerMetrics()
+	s.mtx.Unlock()
+}
+
 func (s *Server) registerMetrics() {
 	metricsHandler := func(w http.ResponseWriter, r *http.Request) {
 		format := strings.TrimSpace(r.FormValue("format"))

server/start.go

@@ -27,11 +27,13 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 	pruningtypes "github.com/cosmos/cosmos-sdk/pruning/types"
 	"github.com/cosmos/cosmos-sdk/server/api"
+	"github.com/cosmos/cosmos-sdk/server/config"
 	serverconfig "github.com/cosmos/cosmos-sdk/server/config"
 	servergrpc "github.com/cosmos/cosmos-sdk/server/grpc"
 	"github.com/cosmos/cosmos-sdk/server/rosetta"
 	crgserver "github.com/cosmos/cosmos-sdk/server/rosetta/lib/server"
 	"github.com/cosmos/cosmos-sdk/server/types"
+	"github.com/cosmos/cosmos-sdk/telemetry"
 	sdktypes "github.com/cosmos/cosmos-sdk/types"
 )
 
@@ -207,6 +209,10 @@ func startStandAlone(ctx *Context, appCreator types.AppCreator) error {
 	}
 
 	app := appCreator(ctx.Logger, db, traceWriter, ctx.Viper)
+	_, err = startTelemetry(serverconfig.GetConfig(ctx.Viper))
+	if err != nil {
+		return err
+	}
 
 	svr, err := server.NewServer(addr, transport, app)
 	if err != nil {
@@ -318,6 +324,11 @@ func startInProcess(ctx *Context, clientCtx client.Context, appCreator types.App
 		app.RegisterTendermintService(clientCtx)
 	}
 
+	metrics, err := startTelemetry(config)
+	if err != nil {
+		return err
+	}
+
 	var apiSrv *api.Server
 	if config.API.Enable {
 		genDoc, err := tmtypes.GenesisDocFromFile(cfg.GenesisFile())
@@ -365,6 +376,9 @@ func startInProcess(ctx *Context, clientCtx client.Context, appCreator types.App
 
 		apiSrv = api.New(clientCtx, ctx.Logger.With("module", "api-server"))
 		app.RegisterAPIRoutes(apiSrv, config.API)
+		if config.Telemetry.Enabled {
+			apiSrv.SetTelemetry(metrics)
+		}
 		errCh := make(chan error)
 
 		go func() {
@@ -487,3 +501,10 @@ func startInProcess(ctx *Context, clientCtx client.Context, appCreator types.App
 	// wait for signal capture and gracefully return
 	return WaitForQuitSignals()
 }
+
+func startTelemetry(cfg config.Config) (*telemetry.Metrics, error) {
+	if !cfg.Telemetry.Enabled {
+		return nil, nil
+	}
+	return telemetry.New(cfg.Telemetry)
+}