Add cloudtail start/stop in recipe_modules/goma

scripts/slave/recipe_modules/goma/resources/cloudtail_utils.py

+#!/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 argparse
+import os
+import signal
+import subprocess
+import sys
+import time
+
+from slave import goma_utils
+
+
+def start_cloudtail(args, f):
+  """Write process id of started cloudtail to file object f"""
+
+  proc = subprocess.Popen([args.cloudtail_path,
+                           'tail',
+                           '--log-id', 'goma_compiler_proxy'
+                           '--path',
+                           goma_utils.GetLatestGomaCompilerProxyInfo()])
+
+  f.write(str(proc.pid))

[Paweł Hajdan Jr., 2016/08/17 13:57:29]

This is a weird structure. Either hardcode sys.stdout here (which is fine -
could even be just print for simplicity), or go all the way and allow specifying
any output file
(https://docs.python.org/2.7/library/argparse.html#filetype-objects). You can
still make it default to sys.stdout.

[tikuta, 2016/08/18 06:17:03]

Done.

+
+
+def main():
+  parser = argparse.ArgumentParser(
+      description='cloudtail utility for goma recipe module.')
+
+  subparsers = parser.add_subparsers(help='commands for cloudtail')
+
+  parser_start = subparsers.add_parser('start',
+                                       help='subcommand to start cloudtail')
+  parser_start.add_argument('--cloudtail-path',

[Paweł Hajdan Jr., 2016/08/17 13:57:29]

Is this a required argument? If so add required=True.

[tikuta, 2016/08/18 06:17:03]

Done.

+                            help='path of cloudtail binary')
+
+  parser_stop = subparsers.add_parser('stop',
+                                      help='subcommand to stop cloudtail')
+  parser_stop.add_argument('--killed-pid', type=int,

[Paweł Hajdan Jr., 2016/08/17 13:57:29]

Same here.

[tikuta, 2016/08/18 06:17:03]

Done.

+                           help='pid that is killed.')
+
+  args = parser.parse_args()
+
+  if args.cloudtail_path:

[Paweł Hajdan Jr., 2016/08/17 13:57:29]

This is close, but for detecting which command to run, it should really use the
subparser command.

See https://github.com/luci/recipes-py/blob/master/recipes.py for a good
example:

fetch_p.set_defaults(command='fetch')

Then use args.command to dispatch.

[tikuta, 2016/08/18 06:17:03]

Done.

+    start_cloudtail(args, sys.stdout)
+  elif args.killed_pid is not None:
+    killed_pid = args.killed_pid
+    # only send SIGKILL signal, let init process do wait for killed_pid

[Paweł Hajdan Jr., 2016/08/17 13:57:29]

nit: Start with capital letter, end with a dot.

[tikuta, 2016/08/18 06:17:03]

Done.

+    os.kill(killed_pid, os.SIGKILL)
+
+
+if '__main__' == __name__:
+  sys.exit(main())