Go's "hello world" of web applications.

main.go

package main

import (
	"fmt"
	"log"
	"net/http"

	"github.com/gorilla/mux"
)

// Constant specifying which port the app should listen on.
const PORT = 8080

// Index is an HTTP handler. It's given a ResponseWriter, which is what
// handlers write to in order to respond to the client, and a pointer to
// a Request struct, which contains information about the request.
func Index(w http.ResponseWriter, r *http.Request) {
	w.Write([]byte("hello world"))
}

func main() {
	// Create the router and set up some endpoints.
	router := mux.NewRouter()
	router.HandleFunc("/", Index)

	// Listen for and serve incoming requests. Requests are served in
	// their own goroutine, aka a lightweight thread.
	log.Printf("-- application is listening on port %d --", PORT)
	if err := http.ListenAndServe(fmt.Sprintf(":%d", PORT), router); err != nil {
		log.Fatal(err)
	}
}