Adds harness from 'revel/revel' and updates imports

harness/harness.go

@@ -0,0 +1,240 @@
+// The Harness for a Revel program.
+//
+// It has a couple responsibilities:
+// 1. Parse the user program, generating a main.go file that registers
+//    controller classes and starts the user's server.
+// 2. Build and run the user program.  Show compile errors.
+// 3. Monitor the user source and re-build / restart the program when necessary.
+//
+// Source files are generated in the app/tmp directory.
+
+package harness
+
+import (
+	"crypto/tls"
+	"fmt"
+	"github.com/revel/revel"
+	"go/build"
+	"io"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"net/url"
+	"os"
+	"os/signal"
+	"path"
+	"path/filepath"
+	"strings"
+	"sync/atomic"
+)
+
+var (
+	watcher    *revel.Watcher
+	doNotWatch = []string{"tmp", "views", "routes"}
+
+	lastRequestHadError int32
+)
+
+// Harness reverse proxies requests to the application server.
+// It builds / runs / rebuilds / restarts the server when code is changed.
+type Harness struct {
+	app        *App
+	serverHost string
+	port       int
+	proxy      *httputil.ReverseProxy
+}
+
+func renderError(w http.ResponseWriter, r *http.Request, err error) {
+	req, resp := revel.NewRequest(r), revel.NewResponse(w)
+	c := revel.NewController(req, resp)
+	c.RenderError(err).Apply(req, resp)
+}
+
+// ServeHTTP handles all requests.
+// It checks for changes to app, rebuilds if necessary, and forwards the request.
+func (hp *Harness) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	// Don't rebuild the app for favicon requests.
+	if lastRequestHadError > 0 && r.URL.Path == "/favicon.ico" {
+		return
+	}
+
+	// Flush any change events and rebuild app if necessary.
+	// Render an error page if the rebuild / restart failed.
+	err := watcher.Notify()
+	if err != nil {
+		atomic.CompareAndSwapInt32(&lastRequestHadError, 0, 1)
+		renderError(w, r, err)
+		return
+	}
+	atomic.CompareAndSwapInt32(&lastRequestHadError, 1, 0)
+
+	// Reverse proxy the request.
+	// (Need special code for websockets, courtesy of bradfitz)
+	if strings.EqualFold(r.Header.Get("Upgrade"), "websocket") {
+		proxyWebsocket(w, r, hp.serverHost)
+	} else {
+		hp.proxy.ServeHTTP(w, r)
+	}
+}
+
+// Return a reverse proxy that forwards requests to the given port.
+func NewHarness() *Harness {
+	// Get a template loader to render errors.
+	// Prefer the app's views/errors directory, and fall back to the stock error pages.
+	revel.MainTemplateLoader = revel.NewTemplateLoader(
+		[]string{path.Join(revel.RevelPath, "templates")})
+	revel.MainTemplateLoader.Refresh()
+
+	addr := revel.HttpAddr
+	port := revel.Config.IntDefault("harness.port", 0)
+	scheme := "http"
+	if revel.HttpSsl {
+		scheme = "https"
+	}
+
+	// If the server is running on the wildcard address, use "localhost"
+	if addr == "" {
+		addr = "localhost"
+	}
+
+	if port == 0 {
+		port = getFreePort()
+	}
+
+	serverUrl, _ := url.ParseRequestURI(fmt.Sprintf(scheme+"://%s:%d", addr, port))
+
+	harness := &Harness{
+		port:       port,
+		serverHost: serverUrl.String()[len(scheme+"://"):],
+		proxy:      httputil.NewSingleHostReverseProxy(serverUrl),
+	}
+
+	if revel.HttpSsl {
+		harness.proxy.Transport = &http.Transport{
+			TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
+		}
+	}
+	return harness
+}
+
+// Rebuild the Revel application and run it on the given port.
+func (h *Harness) Refresh() (err *revel.Error) {
+	if h.app != nil {
+		h.app.Kill()
+	}
+
+	revel.TRACE.Println("Rebuild")
+	h.app, err = Build()
+	if err != nil {
+		return
+	}
+
+	h.app.Port = h.port
+	if err2 := h.app.Cmd().Start(); err2 != nil {
+		return &revel.Error{
+			Title:       "App failed to start up",
+			Description: err2.Error(),
+		}
+	}
+
+	return
+}
+
+func (h *Harness) WatchDir(info os.FileInfo) bool {
+	return !revel.ContainsString(doNotWatch, info.Name())
+}
+
+func (h *Harness) WatchFile(filename string) bool {
+	return strings.HasSuffix(filename, ".go")
+}
+
+// Run the harness, which listens for requests and proxies them to the app
+// server, which it runs and rebuilds as necessary.
+func (h *Harness) Run() {
+	var paths []string
+	if revel.Config.BoolDefault("watch.gopath", false) {
+		gopaths := filepath.SplitList(build.Default.GOPATH)
+		paths = append(paths, gopaths...)
+	}
+	paths = append(paths, revel.CodePaths...)
+	watcher = revel.NewWatcher()
+	watcher.Listen(h, paths...)
+
+	go func() {
+		addr := fmt.Sprintf("%s:%d", revel.HttpAddr, revel.HttpPort)
+		revel.INFO.Printf("Listening on %s", addr)
+
+		var err error
+		if revel.HttpSsl {
+			err = http.ListenAndServeTLS(addr, revel.HttpSslCert,
+				revel.HttpSslKey, h)
+		} else {
+			err = http.ListenAndServe(addr, h)
+		}
+		if err != nil {
+			revel.ERROR.Fatalln("Failed to start reverse proxy:", err)
+		}
+	}()
+
+	// Kill the app on signal.
+	ch := make(chan os.Signal)
+	signal.Notify(ch, os.Interrupt, os.Kill)
+	<-ch
+	if h.app != nil {
+		h.app.Kill()
+	}
+	os.Exit(1)
+}
+
+// Find an unused port
+func getFreePort() (port int) {
+	conn, err := net.Listen("tcp", ":0")
+	if err != nil {
+		revel.ERROR.Fatal(err)
+	}
+
+	port = conn.Addr().(*net.TCPAddr).Port
+	err = conn.Close()
+	if err != nil {
+		revel.ERROR.Fatal(err)
+	}
+	return port
+}
+
+// proxyWebsocket copies data between websocket client and server until one side
+// closes the connection.  (ReverseProxy doesn't work with websocket requests.)
+func proxyWebsocket(w http.ResponseWriter, r *http.Request, host string) {
+	d, err := net.Dial("tcp", host)
+	if err != nil {
+		http.Error(w, "Error contacting backend server.", 500)
+		revel.ERROR.Printf("Error dialing websocket backend %s: %v", host, err)
+		return
+	}
+	hj, ok := w.(http.Hijacker)
+	if !ok {
+		http.Error(w, "Not a hijacker?", 500)
+		return
+	}
+	nc, _, err := hj.Hijack()
+	if err != nil {
+		revel.ERROR.Printf("Hijack error: %v", err)
+		return
+	}
+	defer nc.Close()
+	defer d.Close()
+
+	err = r.Write(d)
+	if err != nil {
+		revel.ERROR.Printf("Error copying request to target: %v", err)
+		return
+	}
+
+	errc := make(chan error, 2)
+	cp := func(dst io.Writer, src io.Reader) {
+		_, err := io.Copy(dst, src)
+		errc <- err
+	}
+	go cp(d, nc)
+	go cp(nc, d)
+	<-errc
+}