Library for running OpenStack services
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# 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 contextlib
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)
with contextlib.closing(sock):
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)
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, b'READY=1')
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, b'READY=1')
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))
with contextlib.closing(sock):
try:
msg = sock.recv(512)
except socket.timeout:
return 2
if b'READY=1' == 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)