Use port decided by OS instead of randomly selecting one

api/grpcserver/grpc.go

@@ -19,7 +19,7 @@ type ServiceAPI interface {
 
 // Server is a very basic grpc server.
 type Server struct {
-	Listener string
+	listener string
 	logger   log.Logger
 	// BoundAddress contains the address that the server bound to, useful if
 	// the server uses a dynamic port. It is set during startup and can be
@@ -34,7 +34,7 @@ type Server struct {
 func New(listener string, lg log.Logger, opts ...grpc.ServerOption) *Server {
 	opts = append(opts, ServerOptions...)
 	return &Server{
-		Listener:   listener,
+		listener:   listener,
 		logger:     lg,
 		GrpcServer: grpc.NewServer(opts...),
 	}
@@ -43,15 +43,15 @@ func New(listener string, lg log.Logger, opts ...grpc.ServerOption) *Server {
 // Start starts the server.
 func (s *Server) Start() error {
 	s.logger.With().Info("starting grpc server",
-		log.String("address", s.Listener),
+		log.String("address", s.listener),
 		log.Array("services", log.ArrayMarshalerFunc(func(encoder log.ArrayEncoder) error {
 			for svc := range s.GrpcServer.GetServiceInfo() {
 				encoder.AppendString(svc)
 			}
 			return nil
 		})),
 	)
-	lis, err := net.Listen("tcp", s.Listener)
+	lis, err := net.Listen("tcp", s.listener)
 	if err != nil {
 		s.logger.Error("error listening: %v", err)
 		return err

api/grpcserver/grpcserver_test.go

@@ -10,7 +10,6 @@ import (
 	"log"
 	"math"
 	"math/big"
-	"math/rand"
 	"net"
 	"net/http"
 	"os"
@@ -478,13 +477,8 @@ func launchServer(tb testing.TB, services ...ServiceAPI) (Config, func()) {
 	cfg := DefaultTestConfig()
 
 	// run on a random port
-	port := 1024 + rand.Intn(9997)
-	cfg.PublicListener = fmt.Sprintf("127.0.0.1:%d", port)
-	cfg.PrivateListener = fmt.Sprintf("127.0.0.1:%d", port+1)
-	cfg.JSONListener = fmt.Sprintf("127.0.0.1:%d", port+2)
-
-	grpcService := New(cfg.PublicListener, logtest.New(tb, zapcore.InfoLevel).Named("grpc"))
-	jsonService := NewJSONHTTPServer(cfg.JSONListener, logtest.New(tb).WithName("grpc.JSON"))
+	grpcService := New("127.0.0.1:0", logtest.New(tb, zapcore.InfoLevel).Named("grpc"))
+	jsonService := NewJSONHTTPServer("127.0.0.1:0", logtest.New(tb).WithName("grpc.JSON"))
 
 	// attach services
 	for _, svc := range services {
@@ -499,6 +493,9 @@ func launchServer(tb testing.TB, services ...ServiceAPI) (Config, func()) {
 		require.NoError(tb, err)
 	}
 
+	cfg.PublicListener = grpcService.BoundAddress
+	cfg.JSONListener = jsonService.BoundAddress
+
 	return cfg, func() {
 		require.NoError(tb, jsonService.Shutdown(context.Background()))
 		_ = grpcService.Close()
@@ -539,7 +536,7 @@ func TestNewServersConfig(t *testing.T) {
 	grpcService := New(fmt.Sprintf(":%d", port1), logtest.New(t).Named("grpc"))
 	jsonService := NewJSONHTTPServer(fmt.Sprintf(":%d", port2), logtest.New(t).WithName("grpc.JSON"))
 
-	require.Contains(t, grpcService.Listener, strconv.Itoa(port1), "Expected same port")
+	require.Contains(t, grpcService.listener, strconv.Itoa(port1), "Expected same port")
 	require.Contains(t, jsonService.listener, strconv.Itoa(port2), "Expected same port")
 }
 

api/grpcserver/http_server.go

@@ -17,11 +17,16 @@ import (
 // JSONHTTPServer is a JSON http server providing the Spacemesh API.
 // It is implemented using a grpc-gateway. See https://github.com/grpc-ecosystem/grpc-gateway .
 type JSONHTTPServer struct {
-	logger log.Logger
-
 	listener string
-	server   *http.Server
-	grp      errgroup.Group
+	logger   log.Logger
+
+	// BoundAddress contains the address that the server bound to, useful if
+	// the server uses a dynamic port. It is set during startup and can be
+	// safely accessed after Start has completed (I.E. the returned channel has
+	// been waited on)
+	BoundAddress string
+	server       *http.Server
+	grp          errgroup.Group
 }
 
 // NewJSONHTTPServer creates a new json http server.
@@ -100,6 +105,7 @@ func (s *JSONHTTPServer) StartService(
 		s.logger.Error("error listening: %v", err)
 		return err
 	}
+	s.BoundAddress = lis.Addr().String()
 	s.server = &http.Server{
 		Handler: mux,
 	}