Add restart_masters.py

scripts/restart_masters.py

Index: scripts/restart_masters.py
diff --git a/scripts/restart_masters.py b/scripts/restart_masters.py
new file mode 100755
index 0000000000000000000000000000000000000000..7405a5ae565a9d36bcbe5a388efe53bd39d3b919
--- /dev/null
+++ b/scripts/restart_masters.py
@@ -0,0 +1,116 @@
+#!/usr/bin/env python
+# Copyright (c) 2014 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.
+
+
+"""Restart the build masters."""
+
+
+import os
+import posixpath
+import sys
+import threading
+import time
+import urllib2
+
+BUILDBOT_PATH = os.path.realpath(os.path.join(os.path.dirname(__file__),
+                                              os.pardir))
+sys.path.append(BUILDBOT_PATH)
+sys.path.append(os.path.join(BUILDBOT_PATH, 'site_config'))
+sys.path.append(os.path.join(BUILDBOT_PATH, 'third_party', 'chromium_buildbot',
+                             'site_config'))
+
+from common.py.utils import shell_utils
+import config_private
+import slave_hosts_cfg
+
+
+# File where the PID of the running master is stored.
+# TODO(borenet): Store the master information in slave_hosts_cfg.py (rename it).
+PID_FILE = posixpath.join('skia-repo', 'buildbot', 'master', 'twistd.pid')
+
+# Number of seconds to wait between checks of whether the master has restarted.
+RESTART_POLL_INTERVAL = 5
+
+# Maximum number of seconds allowed for the master to restart.
+RESTART_TIMEOUT = 180
+
+
+class NoRedirectHandler(urllib2.HTTPErrorProcessor):
+  """Handler which does not follow redirects."""
+  def http_response(self, req, resp):
+    return resp
+
+
+def get_running_pid(master):
+  master_hostname = master.master_fqdn.split('.')[0]
+  pid_cmd = slave_hosts_cfg.compute_engine_login(master_hostname, None)
+  pid_cmd.extend(['cat', PID_FILE])
+  try:
+    return shell_utils.run(pid_cmd, echo=False).splitlines()[-1]
+  except shell_utils.CommandFailedException as e:
+    if 'No such file or directory' in e.output:
+      return None
+    raise
+
+
+def restart_master(master):
+  """Restart the given master.
+
+  Log in to the master host, read the PID file, submit a "clean restart"
+  request, and wait until the master restarts.
+
+  Args:
+      master: config_private.Master.*; the master to restart.
+  """
+  # Obtain the master process PID.
+  old_pid = get_running_pid(master)
+
+  # Submit the "clean restart" request.
+  shutdown_url = 'http://%s:%s/shutdown' % (master.master_host,
+                                            master.master_port)
+  print '%s: Sending shutdown request to %s' % (master.project_name,
+                                                shutdown_url)
+  # Don't follow redirects, since the master might shut down before we can get
+  # a response from the page to which we're redirected.
+  urllib2.build_opener(NoRedirectHandler).open(shutdown_url)
+
+  # Wait until the master restarts.
+  start = time.time()
+  while True:
+    new_pid = get_running_pid(master)
+    if new_pid:
+      if new_pid != old_pid:
+        print '%s finished restarting.' % master.project_name
+        return
+      print '%s is still running.' % master.project_name
+    else:
+      print '%s has shut down but has not yet restarted.' % master.project_name
+    if time.time() - start > RESTART_TIMEOUT:
+      if new_pid:
+        msg = ('%s failed to shut down within %d seconds.' % (
+                   master.project_name, RESTART_TIMEOUT))
+      else:
+        msg = ('%s shut down but failed to restart within %d seconds' % (
+                   master.project_name, RESTART_TIMEOUT))
+      raise Exception(msg)
+    time.sleep(RESTART_POLL_INTERVAL)
+
+
+def main():
+  """Restart the build masters."""
+  threads = []
+
+  for master in config_private.Master.valid_masters:
+    thread = threading.Thread(target=restart_master, args=(master,))
+    thread.daemon = True
+    threads.append(thread)
+    thread.start()
+
+  for thread in threads:
+    thread.join()
+
+
+if '__main__' == __name__:
+  main()