fix: start GRPCWebServer in goroutine (cosmos#9704)

so it don't block other code from executing.

Closes cosmos#9703

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## Description

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---

### Author Checklist

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please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

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your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

CHANGELOG.md

@@ -81,6 +81,7 @@ Ref: https://keepachangelog.com/en/1.0.0/
 * (x/genutil) [\#9574](https://github.com/cosmos/cosmos-sdk/pull/9575) Actually use the `gentx` client tx flags (like `--keyring-dir`)
 * (x/distribution) [\#9599](https://github.com/cosmos/cosmos-sdk/pull/9599) Withdraw rewards event now includes a value attribute even if there are 0 rewards (due to situations like 100% commission).
 * (x/genutil) [\#9638](https://github.com/cosmos/cosmos-sdk/pull/9638) Added missing validator key save when recovering from mnemonic
+* (server) [#9704](https://github.com/cosmos/cosmos-sdk/pull/9704) Start GRPCWebServer in goroutine, avoid blocking other services from starting.
 
 ## [v0.43.0-rc0](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.43.0-rc0) - 2021-06-25
 

server/grpc/grpc_web.go

@@ -1,12 +1,15 @@
 package grpc
 
 import (
+	"fmt"
 	"net/http"
+	"time"
 
 	"github.com/improbable-eng/grpc-web/go/grpcweb"
 	"google.golang.org/grpc"
 
 	"github.com/cosmos/cosmos-sdk/server/config"
+	"github.com/cosmos/cosmos-sdk/server/types"
 )
 
 // StartGRPCWeb starts a gRPC-Web server on the given address.
@@ -28,8 +31,18 @@ func StartGRPCWeb(grpcSrv *grpc.Server, config config.Config) (*http.Server, err
 		Addr:    config.GRPCWeb.Address,
 		Handler: http.HandlerFunc(handler),
 	}
-	if err := grpcWebSrv.ListenAndServe(); err != nil {
+
+	errCh := make(chan error)
+	go func() {
+		if err := grpcWebSrv.ListenAndServe(); err != nil {
+			errCh <- fmt.Errorf("[grpc] failed to serve: %w", err)
+		}
+	}()
+
+	select {
+	case err := <-errCh:
 		return nil, err
+	case <-time.After(types.ServerStartTime): // assume server started successfully
+		return grpcWebSrv, nil
 	}
-	return grpcWebSrv, nil
 }

server/grpc/server.go

@@ -54,7 +54,7 @@ func StartGRPCServer(clientCtx client.Context, app types.Application, address st
 	select {
 	case err := <-errCh:
 		return nil, err
-	case <-time.After(5 * time.Second): // assume server started successfully
+	case <-time.After(types.ServerStartTime): // assume server started successfully
 		return grpcSrv, nil
 	}
 }

server/start.go

@@ -312,7 +312,7 @@ func startInProcess(ctx *Context, clientCtx client.Context, appCreator types.App
 		select {
 		case err := <-errCh:
 			return err
-		case <-time.After(5 * time.Second): // assume server started successfully
+		case <-time.After(types.ServerStartTime): // assume server started successfully
 		}
 	}
 
@@ -366,7 +366,7 @@ func startInProcess(ctx *Context, clientCtx client.Context, appCreator types.App
 		select {
 		case err := <-errCh:
 			return err
-		case <-time.After(5 * time.Second): // assume server started successfully
+		case <-time.After(types.ServerStartTime): // assume server started successfully
 		}
 	}
 

server/types/app.go

@@ -3,6 +3,7 @@ package types
 import (
 	"encoding/json"
 	"io"
+	"time"
 
 	"github.com/gogo/protobuf/grpc"
 	"github.com/spf13/cobra"
@@ -16,6 +17,10 @@ import (
 	"github.com/cosmos/cosmos-sdk/server/config"
 )
 
+// ServerStartTime defines the time duration that the server need to stay running after startup
+// for the startup be considered successful
+const ServerStartTime = 5 * time.Second
+
 type (
 	// AppOptions defines an interface that is passed into an application
 	// constructor, typically used to set BaseApp options that are either supplied

testutil/network/util.go

@@ -16,6 +16,7 @@ import (
 
 	"github.com/cosmos/cosmos-sdk/server/api"
 	servergrpc "github.com/cosmos/cosmos-sdk/server/grpc"
+	srvtypes "github.com/cosmos/cosmos-sdk/server/types"
 	authtypes "github.com/cosmos/cosmos-sdk/x/auth/types"
 	banktypes "github.com/cosmos/cosmos-sdk/x/bank/types"
 	"github.com/cosmos/cosmos-sdk/x/genutil"
@@ -90,7 +91,7 @@ func startInProcess(cfg Config, val *Validator) error {
 		select {
 		case err := <-errCh:
 			return err
-		case <-time.After(5 * time.Second): // assume server started successfully
+		case <-time.After(srvtypes.ServerStartTime): // assume server started successfully
 		}
 
 		val.api = apiSrv
@@ -105,21 +106,10 @@ func startInProcess(cfg Config, val *Validator) error {
 		val.grpc = grpcSrv
 
 		if val.AppConfig.GRPCWeb.Enable {
-			errCh1 := make(chan error)
-			go func() {
-				grpcWeb, err := servergrpc.StartGRPCWeb(grpcSrv, *val.AppConfig)
-				if err != nil {
-					errCh1 <- err
-				}
-
-				val.grpcWeb = grpcWeb
-			}()
-			select {
-			case err := <-errCh1:
+			val.grpcWeb, err = servergrpc.StartGRPCWeb(grpcSrv, *val.AppConfig)
+			if err != nil {
 				return err
-			case <-time.After(5 * time.Second): // assume server started successfully
 			}
-
 		}
 	}