Emit log when emulator successfully starts

[bartolomej]

Issue To Be Solved

Currently, the flow emulator emits logs only when it transitions to "starting" state or to "error" state.

Transition to "starting" state:

> flow emulator
INFO[0000] ⚙️   Using service account 0xf8d6e0586b0a20c7  serviceAddress=f8d6e0586b0a20c7 serviceHashAlgo=SHA3_256 servicePrivKey=17db68f620ff786e3e5a8b87ba577093caece160f7ac57f5c619d86b973b7628 servicePubKey=a8d2074251eb721254004d758cf71d0bf8300651d25d6ef1991c41448ae02b8a61d232cb53a9d0f0b7adefec25fd267ed7bc09dd1490cb201f38b3b5ba783991 serviceSigAlgo=ECDSA_P256
INFO[0000] 📜  Flow contract                              FlowServiceAccount=0xf8d6e0586b0a20c7
INFO[0000] 📜  Flow contract                              FlowToken=0x0ae53cb6e3f42a79
INFO[0000] 📜  Flow contract                              FungibleToken=0xee82856bf20e2aa6
INFO[0000] 📜  Flow contract                              FlowFees=0xe5a8b7f23e8b548f
INFO[0000] 📜  Flow contract                              FlowStorageFees=0xf8d6e0586b0a20c7
INFO[0000] 🌱  Starting gRPC server on port 3569          port=3569
INFO[0000] 🌱  Starting REST API on port 8888             port=8888
INFO[0000] 🌱  Starting admin server on port 8080         port=8080

Transition to "error" state:

> flow emulator
INFO[0000] ⚙️   Using service account 0xf8d6e0586b0a20c7  serviceAddress=f8d6e0586b0a20c7 serviceHashAlgo=SHA3_256 servicePrivKey=17db68f620ff786e3e5a8b87ba577093caece160f7ac57f5c619d86b973b7628 servicePubKey=a8d2074251eb721254004d758cf71d0bf8300651d25d6ef1991c41448ae02b8a61d232cb53a9d0f0b7adefec25fd267ed7bc09dd1490cb201f38b3b5ba783991 serviceSigAlgo=ECDSA_P256
INFO[0000] 📜  Flow contract                              FlowFees=0xe5a8b7f23e8b548f
INFO[0000] 📜  Flow contract                              FlowStorageFees=0xf8d6e0586b0a20c7
INFO[0000] 📜  Flow contract                              FlowServiceAccount=0xf8d6e0586b0a20c7
INFO[0000] 📜  Flow contract                              FlowToken=0x0ae53cb6e3f42a79
INFO[0000] 📜  Flow contract                              FungibleToken=0xee82856bf20e2aa6
ERRO[0000] ❗  Failed to startup REST API                 error="listen tcp :8888: bind: address already in use"

I think it would be good to also emit a log when the emulator started successfully - when it transitions from "starting" to "started" state. This is because currently there is no indication if the emulator indeed started without errors.

Suggest A Solution

Emit "started" info log after all the flow-emulator components were started successfully. This will indicate that no startup errors can occur from now on.

Example output:

INFO[0000] 🌱  Starting gRPC server on port 3569          port=3569
INFO[0000] 🌱  Starting REST API on port 8888             port=8888
INFO[0000] 🌱  Starting admin server on port 8080         port=8080

INFO[0000] ✅  Started gRPC server on port 3569          port=3569
INFO[0000] ✅  Started REST API on port 8888             port=8888
INFO[0000] ✅  Started admin server on port 8080         port=8080

Related code that would need to be modified:

flow-emulator/server/server.go

Lines 189 to 229 in fd49363

	// Start starts the Flow Emulator server.
	func (s *EmulatorServer) Start() {
	s.Stop()
	s.group = graceland.NewGroup()
	// only start blocks ticker if it exists
	if s.blocks != nil {
	s.group.Add(s.blocks)
	}
	s.group.Add(s.liveness)
	s.logger.
	WithField("port", s.config.GRPCPort).
	Infof("🌱 Starting gRPC server on port %d", s.config.GRPCPort)
	s.group.Add(s.grpc)
	s.logger.
	WithField("port", s.config.RESTPort).
	Infof("🌱 Starting REST API on port %d", s.config.RESTPort)
	s.group.Add(s.rest)
	s.logger.
	WithField("port", s.config.AdminPort).
	Infof("🌱 Starting admin server on port %d", s.config.AdminPort)
	s.group.Add(s.admin)
	// only start blocks ticker if it exists
	if s.blocks != nil {
	s.group.Add(s.blocks)
	}
	// routines are shut down in insertion order, so database is added last
	s.group.Add(s.storage)
	err := s.group.Start()
	if err != nil {
	s.logger.WithError(err).Error("❗ Server error")
	}
	s.Stop()
	}

Context

The lack of this log, also makes it harder to detect successful startups programmatically. For example, at Flowser, we currently assume that if no error logs are emitted 1s after "started" logs were seen, the emulator started successfully - which is not ideal.

See our issue: onflowser/flowser#33

[bluesign]

This needs to be logged at Start of each Server.

@sideninja

• Do we keep starting logs or just log started ?
• We can move also port listening to start probably. ( if we will keep starting message )

[sideninja]

@bluesign I believe if we just say starting up (as in general starting up) and then add server started at the end of all services is fine. I believe that would need to change the library we use for that, or we could like you said just announce when each server is started.

[bluesign]

Yeah I think without changing the library would be the easiest, services already have logger for error messages.