DevTools: Add scripts for buildbot to use node.js/npm

third_party/WebKit/Source/devtools/scripts/buildbot/node.py

Index: third_party/WebKit/Source/devtools/scripts/buildbot/node.py
diff --git a/third_party/WebKit/Source/devtools/scripts/buildbot/node.py b/third_party/WebKit/Source/devtools/scripts/buildbot/node.py
new file mode 100755
index 0000000000000000000000000000000000000000..5bb6e6cf298324b007eb461a3f4bf8d9219b47da
--- /dev/null
+++ b/third_party/WebKit/Source/devtools/scripts/buildbot/node.py
@@ -0,0 +1,119 @@
+#!/usr/bin/env python
+# Copyright (c) 2016 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import shutil
+import sys
+import subprocess
+import tarfile
+import tempfile
+import urllib2
+
+THIS_DIR = os.path.dirname(os.path.abspath(__file__))
+
+DEFAULT_VERSION = '0.12.2'
+BUCKET = 'chromium-infra-bins'
+
+
+def install_latest_node_js(version, tmp_dir):
+    target_dir = os.path.join(THIS_DIR, 'runtimes', version)
+    version_file = os.path.join(target_dir, 'VERSION')
+
+    if sys.platform == 'win32':
+        bin_location = os.path.join(target_dir, 'node.exe')
+    else:
+        bin_location = os.path.join(target_dir, 'bin', 'node')
+
+    # We assume that, if the VERSION file exists, then the installation is good.
+    if os.path.exists(version_file):
+        with open(version_file, 'r') as f:
+            if f.read() == version:
+                return bin_location
+
+    # TODO(hinoka): This probably doesn't work that well on Windows...
+    shutil.rmtree(target_dir, ignore_errors=True)
+
+    # Get the target name correct.
+    if sys.platform == 'win32':
+        target = 'node.exe'
+    elif sys.platform == 'darwin':
+        target = 'node-v%s-darwin-x86.tar.gz' % version
+    elif sys.platform == 'linux2':
+        target = 'node-v%s-linux-x86.tar.gz' % version
+    else:
+        raise Exception('Unrecognized platform %s' % sys.platform)
+
+    dest = os.path.join(tmp_dir, 'node_download')
+    url = 'https://storage.googleapis.com/%s/node/%s/%s' % (
+        BUCKET, version, target)
+    print('Fetching %s' % url)
+    u = urllib2.urlopen(url)
+    with open(dest, 'wb') as f:
+        while True:
+            chunk = u.read(2 ** 20)
+            if not chunk:
+                break
+            f.write(chunk)
+
+    # When multiple node.py instances run at the same time for the first time,
+    # the check to see whether or not the installation occured already.  But then
+    # they all race to see who's the first to run shutil.move(), which obviously
+    # fails for everyone other than the first instance.  This CL makes
+    # os.rename() not fail, since its assumed that if it fails that means
+    # someone else already created an installation.
+    #
+    # Another approach is to use an flock, but then it starts to get messy when
+    # you have to keep polling filesystem state to see if another instance
+    # finished, or add timeouts to remove an flock if it was left on the system by
+    # a failed attempt, etc, etc.  This just seemed like a less flaky solution,
+    # despite the fact that it means multiple network requests are spawned.
+    write_version = True
+    if sys.platform != 'win32':
+        # The Windows version comes as a self contained executable, the other
+        # versions come as a tar.gz that needs to be extracted.
+        with tarfile.open(dest, 'r:gz') as f:
+            f.extractall(path=tmp_dir)
+        try:
+            os.mkdir(os.path.join(THIS_DIR, 'runtimes'))
+            os.rename(os.path.join(tmp_dir, target[:-len('.tar.gz')]),
+                      target_dir)
+        except OSError:
+            write_version = False
+        os.remove(dest)
+    else:
+        try:
+            # Still potentiall racy, from python docs:
+            # "On Windows...there may be no way to implement an atomic rename when dst
+            # names an existing file."
+            os.mkdir(target_dir)
+            os.rename(dest, bin_location)
+        except OSError:
+            write_version = False
+
+    if write_version:
+        with open(version_file, 'w') as f:
+            f.write(version)
+
+    return bin_location
+
+
+def main(mode=None):
+    version = os.environ.get('NODE_VERSION', DEFAULT_VERSION)
+    try:
+        tmp_dir = tempfile.mkdtemp(dir=THIS_DIR)
+        bin_location = install_latest_node_js(version, tmp_dir)
+    finally:
+        if os.path.exists(tmp_dir):
+            shutil.rmtree(tmp_dir)
+
+    if mode == 'npm':
+        # TODO(hinoka): How about Windows...?
+        bin_location = os.path.join(os.path.dirname(bin_location), 'npm')
+
+    return subprocess.call([bin_location, ] + sys.argv[1:])
+
+
+if __name__ == '__main__':
+    sys.exit(main())