feat: more meaningful error messages, close body on httpc requests (#2238)

* feat: more meaningful error messages, close body on httpc requests

* fix: test failure

gateway/server.go

@@ -59,6 +59,10 @@ func (s *Server) Stop() {
 }
 
 func (s *Server) build() error {
+	if err := s.ensureUpstreamNames(); err != nil {
+		return err
+	}
+
 	return mr.MapReduceVoid(func(source chan<- interface{}) {
 		for _, up := range s.upstreams {
 			source <- up
@@ -68,13 +72,13 @@ func (s *Server) build() error {
 		cli := zrpc.MustNewClient(up.Grpc)
 		source, err := s.createDescriptorSource(cli, up)
 		if err != nil {
-			cancel(err)
+			cancel(fmt.Errorf("%s: %w", up.Name, err))
 			return
 		}
 
 		methods, err := internal.GetMethods(source)
 		if err != nil {
-			cancel(err)
+			cancel(fmt.Errorf("%s: %w", up.Name, err))
 			return
 		}
 
@@ -95,7 +99,7 @@ func (s *Server) build() error {
 		}
 		for _, m := range up.Mappings {
 			if _, ok := methodSet[m.RpcPath]; !ok {
-				cancel(fmt.Errorf("rpc method %s not found", m.RpcPath))
+				cancel(fmt.Errorf("%s: rpc method %s not found", up.Name, m.RpcPath))
 				return
 			}
 
@@ -162,6 +166,19 @@ func (s *Server) createDescriptorSource(cli zrpc.Client, up Upstream) (grpcurl.D
 	return source, nil
 }
 
+func (s *Server) ensureUpstreamNames() error {
+	for _, up := range s.upstreams {
+		target, err := up.Grpc.BuildTarget()
+		if err != nil {
+			return err
+		}
+
+		up.Name = target
+	}
+
+	return nil
+}
+
 func (s *Server) prepareMetadata(header http.Header) []string {
 	vals := internal.ProcessHeaders(header)
 	if s.processHeader != nil {