Example subdomain routing in github.com/labstack/echo v1.0

echo_hosts.go

package main

import (
	"net/http"

	"github.com/labstack/echo"
)

type Hosts map[string]http.Handler

// Implement a ServeHTTP method for Hosts type.
func (h Hosts) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// Check for host x in the Hosts map.
	if handler := h[r.Host]; handler != nil {
		handler.ServeHTTP(w, r)
	} else {
		// No handler is registered so redirect.
		// Not sure redirect is appropriate here?
		// This is just for illustration, else branch could just as easily return
		// an error for bad port, notFound for bad subdomain etc.
		http.Redirect(w, r, "http://a.localhost:8080", http.StatusTemporaryRedirect)
	}
}

func main() {

	// Some subdomains
	a := echo.New()
	b := echo.New()

	// Host maps.
	hosts := make(Hosts)
	hosts["a.localhost:8080"] = a
	hosts["b.localhost:8080"] = b

	// Handler for subdomain a.
	a.Get("/", func(c *echo.Context) error {
		c.String(http.StatusOK, "Welcome to host a...")
		return nil
	})

	// Handler for subdomain b.
	b.Get("/", func(c *echo.Context) error {
		c.String(http.StatusOK, "Welcome to host b...")
		return nil
	})

	http.ListenAndServe(":8080", hosts)
}