Merge remote-tracking branch 'origin/v3' into issue_132

# Conflicts:
#	grpc.go

grpc.go

@@ -120,6 +120,9 @@ func (g *grpcClient) call(ctx context.Context, addr string, req client.Request,
 		grpc.WithDefaultServiceConfig(cfgService),
 	}
 
+	if opts := g.getGrpcDialOptions(g.opts.Context); opts != nil {
+		grpcDialOptions = append(grpcDialOptions, opts...)
+	}
 	if opts := g.getGrpcDialOptions(opts.Context); opts != nil {
 		grpcDialOptions = append(grpcDialOptions, opts...)
 	}
@@ -730,6 +733,10 @@ func (g *grpcClient) publish(ctx context.Context, ps []client.Message, opts ...c
 	if v, ok := os.LookupEnv("MICRO_PROXY"); ok {
 		exchange = v
 	}
+	// get the exchange
+	if len(options.Exchange) > 0 {
+		exchange = options.Exchange
+	}
 
 	msgs := make([]*broker.Message, 0, len(ps))
 
@@ -741,6 +748,16 @@ func (g *grpcClient) publish(ctx context.Context, ps []client.Message, opts ...c
 	for _, p := range ps {
 		md := metadata.Copy(omd)
 		md[metadata.HeaderContentType] = p.ContentType()
+		topic := p.Topic()
+		if len(exchange) > 0 {
+			topic = exchange
+		}
+		md.Set(metadata.HeaderTopic, topic)
+		iter := p.Metadata().Iterator()
+		var k, v string
+		for iter.Next(&k, &v) {
+			md.Set(k, v)
+		}
 
 		// passed in raw data
 		if d, ok := p.Payload().(*codec.Frame); ok {
@@ -758,16 +775,6 @@ func (g *grpcClient) publish(ctx context.Context, ps []client.Message, opts ...c
 			}
 			body = b
 		}
-
-		topic := p.Topic()
-		if len(exchange) > 0 {
-			topic = exchange
-		}
-
-		for k, v := range p.Metadata() {
-			md.Set(k, v)
-		}
-		md.Set(metadata.HeaderTopic, topic)
 		msgs = append(msgs, &broker.Message{Header: md, Body: body})
 	}