1// Copyright 2011 Google Inc. All rights reserved.
2// Use of this source code is governed by the Apache 2.0
3// license that can be found in the LICENSE file.
4
5// +build !appengine
6
7package internal
8
9import (
10	"io"
11	"log"
12	"net/http"
13	"net/url"
14	"os"
15	"path/filepath"
16	"runtime"
17)
18
19func Main() {
20	MainPath = filepath.Dir(findMainPath())
21	installHealthChecker(http.DefaultServeMux)
22
23	port := "8080"
24	if s := os.Getenv("PORT"); s != "" {
25		port = s
26	}
27
28	host := ""
29	if IsDevAppServer() {
30		host = "127.0.0.1"
31	}
32	if err := http.ListenAndServe(host+":"+port, http.HandlerFunc(handleHTTP)); err != nil {
33		log.Fatalf("http.ListenAndServe: %v", err)
34	}
35}
36
37// Find the path to package main by looking at the root Caller.
38func findMainPath() string {
39	pc := make([]uintptr, 100)
40	n := runtime.Callers(2, pc)
41	frames := runtime.CallersFrames(pc[:n])
42	for {
43		frame, more := frames.Next()
44		// Tests won't have package main, instead they have testing.tRunner
45		if frame.Function == "main.main" || frame.Function == "testing.tRunner" {
46			return frame.File
47		}
48		if !more {
49			break
50		}
51	}
52	return ""
53}
54
55func installHealthChecker(mux *http.ServeMux) {
56	// If no health check handler has been installed by this point, add a trivial one.
57	const healthPath = "/_ah/health"
58	hreq := &http.Request{
59		Method: "GET",
60		URL: &url.URL{
61			Path: healthPath,
62		},
63	}
64	if _, pat := mux.Handler(hreq); pat != healthPath {
65		mux.HandleFunc(healthPath, func(w http.ResponseWriter, r *http.Request) {
66			io.WriteString(w, "ok")
67		})
68	}
69}
70