[baseserver] Allow zero port to automatically assign port

Author: easyCZ

components/common-go/baseserver/options.go

@@ -46,8 +46,8 @@ func WithHostname(hostname string) Option {
 
 func WithHTTPPort(port int) Option {
 	return func(cfg *config) error {
-		if port <= 0 {
-			return fmt.Errorf("http port must be greater than 0, got: %d", port)
+		if port < 0 {
+			return fmt.Errorf("http must not be negative, got: %d", port)
 		}
 
 		cfg.httpPort = port
@@ -58,7 +58,7 @@ func WithHTTPPort(port int) Option {
 func WithGRPCPort(port int) Option {
 	return func(cfg *config) error {
 		if port < 0 {
-			return fmt.Errorf("grpc port must be greater than 0, got: %d", port)
+			return fmt.Errorf("grpc port must not be negative, got: %d", port)
 		}
 
 		cfg.grpcPort = port

components/common-go/baseserver/options_test.go

@@ -37,14 +37,28 @@ func TestOptions(t *testing.T) {
 	}, cfg)
 }
 
-func TestWithTTPPort_ErrorsWithNegativePort(t *testing.T) {
-	_, err := evaluateOptions(defaultConfig(), WithHTTPPort(-1))
-	require.Error(t, err)
+func TestWithTTPPort(t *testing.T) {
+	t.Run("negative", func(t *testing.T) {
+		_, err := evaluateOptions(defaultConfig(), WithHTTPPort(-1))
+		require.Error(t, err)
+	})
+
+	t.Run("zero", func(t *testing.T) {
+		_, err := evaluateOptions(defaultConfig(), WithHTTPPort(0))
+		require.Error(t, err)
+	})
 }
 
-func TestWithGRPCPort_ErrorsWithNegativePort(t *testing.T) {
-	_, err := evaluateOptions(defaultConfig(), WithGRPCPort(-1))
-	require.Error(t, err)
+func TestWithGRPCPort(t *testing.T) {
+	t.Run("negative", func(t *testing.T) {
+		_, err := evaluateOptions(defaultConfig(), WithGRPCPort(-1))
+		require.Error(t, err)
+	})
+
+	t.Run("zero", func(t *testing.T) {
+		_, err := evaluateOptions(defaultConfig(), WithGRPCPort(0))
+		require.Error(t, err)
+	})
 }
 
 func TestLogger_ErrorsWithNilLogger(t *testing.T) {

components/common-go/baseserver/server.go

@@ -132,14 +132,23 @@ func (s *Server) Logger() *logrus.Entry {
 	return s.cfg.logger
 }
 
+// HTTPAddress returns address of the HTTP Server
+// HTTPAddress() is only available once the server has been started.
 func (s *Server) HTTPAddress() string {
+	if s.httpListener == nil {
+		return ""
+	}
 	protocol := "http"
-	return fmt.Sprintf("%s://%s:%d", protocol, s.cfg.hostname, s.cfg.httpPort)
+	addr := s.httpListener.Addr().(*net.TCPAddr)
+	return fmt.Sprintf("%s://%s:%d", protocol, addr.IP, addr.Port)
 }
 
+// GRPCAddress returns address of the gRPC Server
+// GRPCAddress() is only available once the server has been started.
 func (s *Server) GRPCAddress() string {
 	protocol := "http"
-	return fmt.Sprintf("%s://%s:%d", protocol, s.cfg.hostname, s.cfg.grpcPort)
+	addr := s.grpcListener.Addr().(*net.TCPAddr)
+	return fmt.Sprintf("%s://%s:%d", protocol, addr.IP, addr.Port)
 }
 
 func (s *Server) HTTPMux() *http.ServeMux {

components/common-go/baseserver/server_test.go

@@ -35,8 +35,8 @@ func TestServer_ServesReady(t *testing.T) {
 
 	baseserver.WaitForServerToBeReachable(t, srv, 3*time.Second)
 
-	readyUR := fmt.Sprintf("%s/ready", srv.HTTPAddress())
-	resp, err := http.Get(readyUR)
+	readyURL := fmt.Sprintf("%s/ready", srv.HTTPAddress())
+	resp, err := http.Get(readyURL)
 	require.NoError(t, err)
 	require.Equal(t, http.StatusOK, resp.StatusCode)
 }

components/common-go/baseserver/testing.go

@@ -18,6 +18,8 @@ func NewForTests(t *testing.T, opts ...Option) *Server {
 	t.Helper()
 
 	defaultTestOpts := []Option{
+		WithGRPCPort(0),
+		WithHTTPPort(0),
 		WithCloseTimeout(1 * time.Second),
 	}
 
@@ -44,13 +46,13 @@ func WaitForServerToBeReachable(t *testing.T, srv *Server, timeout time.Duration
 		Timeout: tick,
 	}
 
-	healthURL := fmt.Sprintf("%s/ready", srv.HTTPAddress())
-
 	for {
 		select {
 		case <-ctx.Done():
 			require.Failf(t, "server did not become reachable in %s", timeout.String())
 		case <-ticker.C:
+			// We retrieve the URL on each tick, because the HTTPAddress is only available once the server is listening.
+			healthURL := fmt.Sprintf("%s/ready", srv.HTTPAddress())
 			_, err := client.Get(healthURL)
 			if err != nil {
 				continue