Go stdlib http server with api and embedded SPA (e.g. React)

main.go

package main

import (
	"embed"
	"encoding/json"
	"fmt"
	"io"
	"io/fs"
	"log"
	"net/http"
)

//go:embed static
var staticFiles embed.FS

type CreateRequest struct {
	Name string `json:"name"`
}

type APIResponse struct {
	Message string `json:"message"`
}

type CreateResponse struct {
	Created string `json:"created"`
}

func main() {
	mux := http.NewServeMux()

	// Serve static files from embedded FS at root
	// Since we embedded "static", we need to serve from the "static" subdirectory
	staticFS, err := http.FS(staticFiles).Open("static")
	if err != nil {
		log.Fatal("Failed to open static directory:", err)
	}
	staticFS.Close()

	// Create a sub filesystem that serves from the static directory
	subFS, err := fs.Sub(staticFiles, "static")
	if err != nil {
		log.Fatal("Failed to create sub filesystem:", err)
	}

	staticHandler := http.FileServer(http.FS(subFS))
	mux.Handle("/", staticHandler)

	// API endpoint that returns JSON
	mux.HandleFunc("GET /api", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		response := APIResponse{Message: "hello from api"}
		json.NewEncoder(w).Encode(response)
	})

	// POST endpoint for creating
	mux.HandleFunc("POST /api/create", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")

		body, err := io.ReadAll(r.Body)
		if err != nil {
			http.Error(w, "Failed to read request body", http.StatusBadRequest)
			return
		}
		defer r.Body.Close()

		var req CreateRequest
		if err := json.Unmarshal(body, &req); err != nil {
			http.Error(w, "Invalid JSON", http.StatusBadRequest)
			return
		}

		// Log the received name for debugging
		log.Printf("Received create request for: %s", req.Name)

		response := CreateResponse{Created: "ok"}
		json.NewEncoder(w).Encode(response)
	})

	fmt.Println("Server starting on port 16000...")
	fmt.Println("Static files served from: /")
	fmt.Println("API endpoint: GET /api")
	fmt.Println("Create endpoint: POST /api/create")

	log.Fatal(http.ListenAndServe(":16000", mux))
}