Function runProxyServer

examples/server/proxy/main.go:72–110

Proxy Server: Forwards requests to the backend with headers.

(ctx context.Context)

// Proxy Server: Forwards requests to the backend with headers.
func runProxyServer(ctx context.Context) {
	// Connect to the backend server (acting as a client).
	client := mcp.NewClient(&mcp.Implementation{Name: "proxy-client", Version: "1.0.0"}, nil)
	clientSession, err := client.Connect(ctx, &mcp.StreamableClientTransport{
		Endpoint:   "http://localhost:8082/mcp",
		HTTPClient: NewHeaderForwardingClient(),
	}, nil)
	if err != nil {
		log.Fatalf("Failed to connect to backend: %v", err)
	}
	defer clientSession.Close()

	server := mcp.NewServer(&mcp.Implementation{Name: "proxy-server", Version: "1.0.0"}, nil)
	// Add a tool that forwards the call to the backend.
	mcp.AddTool(server, &mcp.Tool{
		Name:        "forward_headers",
		Description: "Calls the backend server, ensuring headers are propagated",
	}, func(ctx context.Context, req *mcp.CallToolRequest, args struct{}) (*mcp.CallToolResult, any, error) {
		incomingHeaders := req.Extra.Header
		log.Printf("Gateway received headers: %v", incomingHeaders)
		propagateCtx := context.WithValue(ctx, headerContextKey, incomingHeaders)
		result, err := clientSession.CallTool(propagateCtx, &mcp.CallToolParams{
			Name: "echo_headers",
		})
		if err != nil {
			return nil, nil, fmt.Errorf("failed to call backend: %w", err)
		}

		return result, nil, nil
	})

	// Start the gateway server on port 8081.
	log.Println("Starting Gateway Server on :8081")
	if err := http.ListenAndServe(":8081", mcp.NewStreamableHTTPHandler(func(r *http.Request) *mcp.Server {
		return server
	}, nil)); err != nil {
		log.Fatal(err)
	}
}

func runClient(ctx context.Context) {
	// Connect to the proxy server (acting as a client).