cmd/tip/tip.go - tools - Git at Google

 // 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 = 10 * 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("/", httpsOnlyHandler{p})
 	http.HandleFunc("/_ah/health", p.serveHealthCheck)

 	log.Print("Starting up")

 	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
 	}
 	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()
 	// NOTE: Status 502, 503, 504 are the only status codes that signify an unhealthy app.
 	// So long as this handler returns one of those codes, this instance will not be sent any requests.
 	if p.proxy == nil {
 		log.Printf("Health check: not ready")
 		http.Error(w, "Not ready", http.StatusServiceUnavailable)
 		return
 	}

 	if err := p.builder.HealthCheck(p.hostport); err != nil {
 		log.Printf("Health check failed: %v", err)
 		http.Error(w, "Health check failed", http.StatusServiceUnavailable)
 		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 {
 		err = fmt.Errorf("builder.Init: %v", err)
 	} else {
 		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)
 		if err != nil {
 			cmd.Process.Kill()
 			err = fmt.Errorf("waitReady: %v", err)
 		}
 	}

 	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 {
 		err = fmt.Errorf("parsing hostport: %v", err)
 		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 fmt.Errorf("mkdir: %v", err)
 		}
 		if err := runErr(exec.Command("git", "clone", repo, path)); err != nil {
 			return fmt.Errorf("clone: %v", err)
 		}
 	} else if err != nil {
 		return fmt.Errorf("stat .git: %v", err)
 	}

 	// Pull down changes and update to hash.
 	cmd := exec.Command("git", "fetch")
 	cmd.Dir = path
 	if err := runErr(cmd); err != nil {
 		return fmt.Errorf("fetch: %v", err)
 	}
 	cmd = exec.Command("git", "reset", "--hard", hash)
 	cmd.Dir = path
 	if err := runErr(cmd); err != nil {
 		return fmt.Errorf("reset: %v", err)
 	}
 	cmd = exec.Command("git", "clean", "-d", "-f", "-x")
 	cmd.Dir = path
 	if err := runErr(cmd); err != nil {
 		return fmt.Errorf("clean: %v", err)
 	}
 	return nil
 }

 // 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
 }

 // httpsOnlyHandler redirects requests to "http://example.com/foo?bar"
 // to "https://example.com/foo?bar"
 type httpsOnlyHandler struct {
 	h http.Handler
 }

 func (h httpsOnlyHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 	if r.Header.Get("X-Appengine-Https") == "off" {
 		r.URL.Scheme = "https"
 		r.URL.Host = r.Host
 		http.Redirect(w, r, r.URL.String(), http.StatusFound)
 		return
 	}
 	h.h.ServeHTTP(w, r)
 }
	// 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 = 10 * 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("/", httpsOnlyHandler{p})
	http.HandleFunc("/_ah/health", p.serveHealthCheck)

	log.Print("Starting up")

	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
	}
	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()
	// NOTE: Status 502, 503, 504 are the only status codes that signify an unhealthy app.
	// So long as this handler returns one of those codes, this instance will not be sent any requests.
	if p.proxy == nil {
	log.Printf("Health check: not ready")
	http.Error(w, "Not ready", http.StatusServiceUnavailable)
	return
	}

	if err := p.builder.HealthCheck(p.hostport); err != nil {
	log.Printf("Health check failed: %v", err)
	http.Error(w, "Health check failed", http.StatusServiceUnavailable)
	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 {
	err = fmt.Errorf("builder.Init: %v", err)
	} else {
	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)
	if err != nil {
	cmd.Process.Kill()
	err = fmt.Errorf("waitReady: %v", err)
	}
	}

	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 {
	err = fmt.Errorf("parsing hostport: %v", err)
	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 fmt.Errorf("mkdir: %v", err)
	}
	if err := runErr(exec.Command("git", "clone", repo, path)); err != nil {
	return fmt.Errorf("clone: %v", err)
	}
	} else if err != nil {
	return fmt.Errorf("stat .git: %v", err)
	}

	// Pull down changes and update to hash.
	cmd := exec.Command("git", "fetch")
	cmd.Dir = path
	if err := runErr(cmd); err != nil {
	return fmt.Errorf("fetch: %v", err)
	}
	cmd = exec.Command("git", "reset", "--hard", hash)
	cmd.Dir = path
	if err := runErr(cmd); err != nil {
	return fmt.Errorf("reset: %v", err)
	}
	cmd = exec.Command("git", "clean", "-d", "-f", "-x")
	cmd.Dir = path
	if err := runErr(cmd); err != nil {
	return fmt.Errorf("clean: %v", err)
	}
	return nil
	}

	// 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
	}

	// httpsOnlyHandler redirects requests to "http://example.com/foo?bar"
	// to "https://example.com/foo?bar"
	type httpsOnlyHandler struct {
	h http.Handler
	}

	func (h httpsOnlyHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if r.Header.Get("X-Appengine-Https") == "off" {
	r.URL.Scheme = "https"
	r.URL.Host = r.Host
	http.Redirect(w, r, r.URL.String(), http.StatusFound)
	return
	}
	h.h.ServeHTTP(w, r)
	}