Source code for keystone.openstack.common.systemd

# Copyright 2012-2014 Red Hat, Inc.
#
#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

"""
Helper module for systemd service readiness notification.
"""

import logging
import os
import socket
import sys


LOG = logging.getLogger(__name__)


def _abstractify(socket_name):
    if socket_name.startswith('@'):
        # abstract namespace socket
        socket_name = '\0%s' % socket_name[1:]
    return socket_name


def _sd_notify(unset_env, msg):
    notify_socket = os.getenv('NOTIFY_SOCKET')
    if notify_socket:
        sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
        try:
            sock.connect(_abstractify(notify_socket))
            sock.sendall(msg)
            if unset_env:
                del os.environ['NOTIFY_SOCKET']
        except EnvironmentError:
            LOG.debug("Systemd notification failed", exc_info=True)
        finally:
            sock.close()


[docs]def notify(): """Send notification to Systemd that service is ready. For details see http://www.freedesktop.org/software/systemd/man/sd_notify.html """ _sd_notify(False, 'READY=1')
[docs]def notify_once(): """Send notification once to Systemd that service is ready. Systemd sets NOTIFY_SOCKET environment variable with the name of the socket listening for notifications from services. This method removes the NOTIFY_SOCKET environment variable to ensure notification is sent only once. """ _sd_notify(True, 'READY=1')
[docs]def onready(notify_socket, timeout): """Wait for systemd style notification on the socket. :param notify_socket: local socket address :type notify_socket: string :param timeout: socket timeout :type timeout: float :returns: 0 service ready 1 service not ready 2 timeout occurred """ sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM) sock.settimeout(timeout) sock.bind(_abstractify(notify_socket)) try: msg = sock.recv(512) except socket.timeout: return 2 finally: sock.close() if 'READY=1' in msg: return 0 else: return 1
if __name__ == '__main__': # simple CLI for testing if len(sys.argv) == 1: notify() elif len(sys.argv) >= 2: timeout = float(sys.argv[1]) notify_socket = os.getenv('NOTIFY_SOCKET') if notify_socket: retval = onready(notify_socket, timeout) sys.exit(retval)