/
tip.go
312 lines (284 loc) · 6.53 KB
/
tip.go
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// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by the Apache 2.0
// license that can be found in the LICENSE file.
// Command tipgodoc is the beginning of the new tip.golang.org server,
// serving the latest HEAD straight from the Git oven.
package main
import (
"bufio"
"encoding/json"
"errors"
"fmt"
"io"
"io/ioutil"
"log"
"net/http"
"net/http/httputil"
"net/url"
"os"
"os/exec"
"path/filepath"
"sync"
"time"
)
const (
repoURL = "https://go.googlesource.com/"
metaURL = "https://go.googlesource.com/?b=master&format=JSON"
startTimeout = 5 * time.Minute
)
func main() {
const k = "TIP_BUILDER"
var b Builder
switch os.Getenv(k) {
case "godoc":
b = godocBuilder{}
case "talks":
b = talksBuilder{}
default:
log.Fatalf("Unknown %v value: %q", k, os.Getenv(k))
}
p := &Proxy{builder: b}
go p.run()
http.Handle("/", p)
http.HandleFunc("/_ah/health", p.serveHealthCheck)
if err := http.ListenAndServe(":8080", nil); err != nil {
p.stop()
log.Fatal(err)
}
}
// Proxy implements the tip.golang.org server: a reverse-proxy
// that builds and runs godoc instances showing the latest docs.
type Proxy struct {
builder Builder
mu sync.Mutex // protects the followin'
proxy http.Handler
cur string // signature of gorepo+toolsrepo
cmd *exec.Cmd // live godoc instance, or nil for none
side string
hostport string // host and port of the live instance
err error
}
type Builder interface {
Signature(heads map[string]string) string
Init(dir, hostport string, heads map[string]string) (*exec.Cmd, error)
HealthCheck(hostport string) error
}
func (p *Proxy) ServeHTTP(w http.ResponseWriter, r *http.Request) {
if r.URL.Path == "/_tipstatus" {
p.serveStatus(w, r)
return
}
p.mu.Lock()
proxy := p.proxy
err := p.err
p.mu.Unlock()
if proxy == nil {
s := "starting up"
if err != nil {
s = err.Error()
}
http.Error(w, s, http.StatusInternalServerError)
return
}
if r.URL.Path == "/_ah/health" {
if err := p.builder.HealthCheck(p.hostport); err != nil {
http.Error(w, "Health check failde: "+err.Error(), http.StatusInternalServerError)
return
}
fmt.Fprintln(w, "OK")
return
}
proxy.ServeHTTP(w, r)
}
func (p *Proxy) serveStatus(w http.ResponseWriter, r *http.Request) {
p.mu.Lock()
defer p.mu.Unlock()
fmt.Fprintf(w, "side=%v\ncurrent=%v\nerror=%v\n", p.side, p.cur, p.err)
}
func (p *Proxy) serveHealthCheck(w http.ResponseWriter, r *http.Request) {
p.mu.Lock()
defer p.mu.Unlock()
if p.proxy == nil {
http.Error(w, "not ready", 500)
return
}
io.WriteString(w, "ok")
}
// run runs in its own goroutine.
func (p *Proxy) run() {
p.side = "a"
for {
p.poll()
time.Sleep(30 * time.Second)
}
}
func (p *Proxy) stop() {
p.mu.Lock()
defer p.mu.Unlock()
if p.cmd != nil {
p.cmd.Process.Kill()
}
}
// poll runs from the run loop goroutine.
func (p *Proxy) poll() {
heads := gerritMetaMap()
if heads == nil {
return
}
sig := p.builder.Signature(heads)
p.mu.Lock()
changes := sig != p.cur
curSide := p.side
p.cur = sig
p.mu.Unlock()
if !changes {
return
}
newSide := "b"
if curSide == "b" {
newSide = "a"
}
dir := filepath.Join(os.TempDir(), "tip", newSide)
if err := os.MkdirAll(dir, 0755); err != nil {
p.err = err
return
}
hostport := "localhost:8081"
if newSide == "b" {
hostport = "localhost:8082"
}
cmd, err := p.builder.Init(dir, hostport, heads)
if err == nil {
go func() {
// TODO(adg,bradfitz): be smarter about dead processes
if err := cmd.Wait(); err != nil {
log.Printf("process in %v exited: %v", dir, err)
}
}()
err = waitReady(p.builder, hostport)
}
p.mu.Lock()
defer p.mu.Unlock()
if err != nil {
log.Println(err)
p.err = err
return
}
u, err := url.Parse(fmt.Sprintf("http://%v/", hostport))
if err != nil {
log.Println(err)
p.err = err
return
}
p.proxy = httputil.NewSingleHostReverseProxy(u)
p.side = newSide
p.hostport = hostport
if p.cmd != nil {
p.cmd.Process.Kill()
}
p.cmd = cmd
}
func waitReady(b Builder, hostport string) error {
var err error
deadline := time.Now().Add(startTimeout)
for time.Now().Before(deadline) {
if err = b.HealthCheck(hostport); err == nil {
return nil
}
time.Sleep(time.Second)
}
return fmt.Errorf("timed out waiting for process at %v: %v", hostport, err)
}
func runErr(cmd *exec.Cmd) error {
out, err := cmd.CombinedOutput()
if err != nil {
if len(out) == 0 {
return err
}
return fmt.Errorf("%s\n%v", out, err)
}
return nil
}
func checkout(repo, hash, path string) error {
// Clone git repo if it doesn't exist.
if _, err := os.Stat(filepath.Join(path, ".git")); os.IsNotExist(err) {
if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
return err
}
if err := runErr(exec.Command("git", "clone", repo, path)); err != nil {
return err
}
} else if err != nil {
return err
}
// Pull down changes and update to hash.
cmd := exec.Command("git", "fetch")
cmd.Dir = path
if err := runErr(cmd); err != nil {
return err
}
cmd = exec.Command("git", "reset", "--hard", hash)
cmd.Dir = path
if err := runErr(cmd); err != nil {
return err
}
cmd = exec.Command("git", "clean", "-d", "-f", "-x")
cmd.Dir = path
return runErr(cmd)
}
// gerritMetaMap returns the map from repo name (e.g. "go") to its
// latest master hash.
// The returned map is nil on any transient error.
func gerritMetaMap() map[string]string {
res, err := http.Get(metaURL)
if err != nil {
return nil
}
defer res.Body.Close()
defer io.Copy(ioutil.Discard, res.Body) // ensure EOF for keep-alive
if res.StatusCode != 200 {
return nil
}
var meta map[string]struct {
Branches map[string]string
}
br := bufio.NewReader(res.Body)
// For security reasons or something, this URL starts with ")]}'\n" before
// the JSON object. So ignore that.
// Shawn Pearce says it's guaranteed to always be just one line, ending in '\n'.
for {
b, err := br.ReadByte()
if err != nil {
return nil
}
if b == '\n' {
break
}
}
if err := json.NewDecoder(br).Decode(&meta); err != nil {
log.Printf("JSON decoding error from %v: %s", metaURL, err)
return nil
}
m := map[string]string{}
for repo, v := range meta {
if master, ok := v.Branches["master"]; ok {
m[repo] = master
}
}
return m
}
func getOK(url string) (body []byte, err error) {
res, err := http.Get(url)
if err != nil {
return nil, err
}
body, err = ioutil.ReadAll(res.Body)
res.Body.Close()
if err != nil {
return nil, err
}
if res.StatusCode != http.StatusOK {
return nil, errors.New(res.Status)
}
return body, nil
}