http-go-status/main.go

package main

import (
	"fmt"
	"log"
	"net/http"
	"os"
	"strconv"
	"strings"

	"github.com/julienschmidt/httprouter"
)

func Status(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
	header := w.Header()
	header.Set("Access-Control-Allow-Origin", "*")

	status := ps.ByName("status")
	fmt.Printf("Got %s status\n", status)
	if status == "" {
		status = "200"
	}

	ret, err := strconv.Atoi(status)

	if err != nil || ret < 100 || ret > 599 {
		if err != nil {
			fmt.Printf("Got an error: %s\n", err.Error())
		} else {
			fmt.Printf("Requested status %d\n", ret)
		}
		ret = 200
	}
	fmt.Printf("Returning %d\n", ret)

	w.WriteHeader(ret)
}

func GetRouter() *httprouter.Router {
	router := httprouter.New()

	// We don't handle OPTIONS, so that we can support CORS
	methods := [8]string{
		http.MethodGet,
		http.MethodHead,
		http.MethodPost,
		http.MethodPut,
		http.MethodPatch,
		http.MethodDelete,
		http.MethodConnect,
		http.MethodTrace}
	for _, method := range methods {
		router.Handle(method, "/:status", Status)
	}

	// Handle CORS preflight requests
	router.GlobalOPTIONS = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if r.Header.Get("Access-Control-Request-Method") != "" {
			// Set CORS headers
			header := w.Header()
			header.Set("Access-Control-Allow-Methods", header.Get("Allow"))
			header.Set("Access-Control-Allow-Origin", "*")
		}

		// Adjust status code to 204
		w.WriteHeader(http.StatusNoContent)
	})

	return router
}

func GetPort() string {
	port := os.Getenv("PORT")
	if port == "" {
		port = ":8080"
	}
	if !strings.HasPrefix(port, ":") {
		port = ":" + port
	}

	return port
}

func main() {
	port := GetPort()
	fmt.Printf("Listening on %s\n", port)
	log.Fatal(http.ListenAndServe(port, GetRouter()))
}