feat: support serverless in rest (#5001)

Signed-off-by: kevin <wanjunfeng@gmail.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

rest/server.go

@@ -119,6 +119,16 @@ func (s *Server) Use(middleware Middleware) {
 	s.ngin.use(middleware)
 }
 
+// build builds the Server and binds the routes to the router.
+func (s *Server) build() error {
+	return s.ngin.bindRoutes(s.router)
+}
+
+// serve serves the HTTP requests using the Server's router.
+func (s *Server) serve(w http.ResponseWriter, r *http.Request) {
+	s.router.ServeHTTP(w, r)
+}
+
 // ToMiddleware converts the given handler to a Middleware.
 func ToMiddleware(handler func(next http.Handler) http.Handler) Middleware {
 	return func(handle http.HandlerFunc) http.HandlerFunc {

rest/server_test.go

@@ -819,6 +819,6 @@ func TestServerEmbedFileSystem(t *testing.T) {
 //	serve(server, w, r)
 //	// verify the response
 func serve(s *Server, w http.ResponseWriter, r *http.Request) {
-	s.ngin.bindRoutes(s.router)
-	s.router.ServeHTTP(w, r)
+	_ = s.build()
+	s.serve(w, r)
 }

rest/serverless.go

@@ -0,0 +1,27 @@
+package rest
+
+import "net/http"
+
+// Serverless is a wrapper around Server that allows it to be used in serverless environments.
+type Serverless struct {
+	server *Server
+}
+
+// NewServerless creates a new Serverless instance from the provided Server.
+func NewServerless(server *Server) (*Serverless, error) {
+	// Ensure the server is built before using it in a serverless context.
+	// Why not call server.build() when serving requests,
+	// is because we need to ensure fail fast behavior.
+	if err := server.build(); err != nil {
+		return nil, err
+	}
+
+	return &Serverless{
+		server: server,
+	}, nil
+}
+
+// Serve handles HTTP requests by delegating them to the underlying Server instance.
+func (s *Serverless) Serve(w http.ResponseWriter, r *http.Request) {
+	s.server.serve(w, r)
+}

rest/serverless_test.go

@@ -0,0 +1,67 @@
+package rest
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/zeromicro/go-zero/core/conf"
+	"github.com/zeromicro/go-zero/core/logx/logtest"
+)
+
+func TestNewServerless(t *testing.T) {
+	logtest.Discard(t)
+
+	const configYaml = `
+Name: foo
+Host: localhost
+Port: 0
+`
+	var cnf RestConf
+	assert.Nil(t, conf.LoadFromYamlBytes([]byte(configYaml), &cnf))
+
+	svr, err := NewServer(cnf)
+	assert.NoError(t, err)
+
+	svr.AddRoute(Route{
+		Method: http.MethodGet,
+		Path:   "/",
+		Handler: func(w http.ResponseWriter, r *http.Request) {
+			w.Write([]byte("Hello World"))
+		},
+	})
+
+	serverless, err := NewServerless(svr)
+	assert.NoError(t, err)
+
+	w := httptest.NewRecorder()
+	r := httptest.NewRequest(http.MethodGet, "/", nil)
+	serverless.Serve(w, r)
+	assert.Equal(t, http.StatusOK, w.Code)
+	assert.Equal(t, "Hello World", w.Body.String())
+}
+
+func TestNewServerlessWithError(t *testing.T) {
+	logtest.Discard(t)
+
+	const configYaml = `
+Name: foo
+Host: localhost
+Port: 0
+`
+	var cnf RestConf
+	assert.Nil(t, conf.LoadFromYamlBytes([]byte(configYaml), &cnf))
+
+	svr, err := NewServer(cnf)
+	assert.NoError(t, err)
+
+	svr.AddRoute(Route{
+		Method:  http.MethodGet,
+		Path:    "notstartwith/",
+		Handler: nil,
+	})
+
+	_, err = NewServerless(svr)
+	assert.Error(t, err)
+}