Gin Golang handle multi sub-domain

gin-multi-subdomain.go

package main

import (
	"net/http"
	"strings"

	"github.com/gin-gonic/gin"
)

// Create a subdomainHandler type that implements http.Handler interface
type subdomainHandler struct {
	routers map[string]*gin.Engine // a map of routers for each subdomain
}

// Implement the ServeHTTP method for subdomainHandler
func (s *subdomainHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// Get the subdomain from the Host header
	host := r.Host
	subdomain := strings.Split(host, ".")[0]
	// Check if there is a router for the subdomain
	if router, ok := s.routers[subdomain]; ok {
		// Use the router to handle the request
		router.ServeHTTP(w, r)
	} else {
		// No router found, return an error
		http.Error(w, "Not found", 404)
	}
}

// Create a newSubdomainHandler function that returns a new subdomainHandler with the given routers
func newSubdomainHandler(routers map[string]*gin.Engine) *subdomainHandler {
	return &subdomainHandler{routers: routers}
}

// In the main function, create different routers for each subdomain and pass them to the newSubdomainHandler function
func main() {
	// Create a router for the api domain
	api := gin.Default()
	api.GET("/", func(c *gin.Context) {
		c.String(200, "Welcome to the API")
	})

	// Create a router for the admin subdomain
	app := gin.Default()
	app.GET("/", func(c *gin.Context) {
		c.String(200, "Welcome to the app")
	})

	// Create a map of routers for each subdomain
	routers := map[string]*gin.Engine{
		"api": api,
		"app": app,
	}

	handler := newSubdomainHandler(routers)
	http.ListenAndServe(":8080", handler)
}