1 files changed, 78 insertions, 0 deletions
diff --git a/dashboard/buildlet/stage0/stage0.go b/dashboard/buildlet/stage0/stage0.go
new file mode 100644
index 0000000..609c5c8
--- /dev/null
+++ b/dashboard/buildlet/stage0/stage0.go
@@ -0,0 +1,78 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// +build stage0
+
+// The stage0 command looks up the buildlet's URL from the GCE metadata
+// service, downloads it, and runs it. It's used primarily by Windows,
+// since it can be written in a couple lines of shell elsewhere.
+package main
+
+import (
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"time"
+
+	"google.golang.org/cloud/compute/metadata"
+)
+
+const attr = "buildlet-binary-url"
+
+func main() {
+	buildletURL, err := metadata.InstanceAttributeValue(attr)
+	if err != nil {
+		sleepFatalf("Failed to look up %q attribute value: %v", attr, err)
+	}
+	target := filepath.FromSlash("./buildlet.exe")
+	if err := download(target, buildletURL); err != nil {
+		sleepFatalf("Downloading %s: %v", buildletURL, err)
+	}
+	cmd := exec.Command(target)
+	cmd.Stdout = os.Stdout
+	cmd.Stderr = os.Stderr
+	if err := cmd.Run(); err != nil {
+		sleepFatalf("Error running buildlet: %v", err)
+	}
+}
+
+func sleepFatalf(format string, args ...interface{}) {
+	log.Printf(format, args...)
+	time.Sleep(time.Minute) // so user has time to see it in cmd.exe, maybe
+	os.Exit(1)
+}
+
+func download(file, url string) error {
+	log.Printf("Downloading %s to %s ...\n", url, file)
+	res, err := http.Get(url)
+	if err != nil {
+		return fmt.Errorf("Error fetching %v: %v", url, err)
+	}
+	if res.StatusCode != 200 {
+		return fmt.Errorf("HTTP status code of %s was %v", url, res.Status)
+	}
+	tmp := file + ".tmp"
+	os.Remove(tmp)
+	os.Remove(file)
+	f, err := os.Create(tmp)
+	if err != nil {
+		return err
+	}
+	n, err := io.Copy(f, res.Body)
+	res.Body.Close()
+	if err != nil {
+		return fmt.Errorf("Error reading %v: %v", url, err)
+	}
+	f.Close()
+	err = os.Rename(tmp, file)
+	if err != nil {
+		return err
+	}
+	log.Printf("Downloaded %s (%d bytes)", file, n)
+	return nil
+}