Add systemd notification support to heat

This mirrors work done in other OpenStack projects
to add systemd notification support to signal that
a given process is ready to accept requests.

The heat-api, heat-api-cfn, heat-engine, and
heat-api-cloudwatch processes are all covered by
a new, single, 'onready' configuration file option.

Additionally, the sample configuration file has been
updated to match.

Implements: blueprint systemd-integration

Change-Id: I90d2b915e2568a65ed9ed78923c9982e19f9c948
Signed-off-by: Lon Hohberger <lhh@redhat.com>

bin/heat-api

@@ -40,6 +40,7 @@ from oslo.config import cfg
 
 from heat.common import config
 from heat.common import wsgi
+from heat.common import notify
 
 from heat.openstack.common import log as logging
 
@@ -62,6 +63,7 @@ if __name__ == '__main__':
         LOG.info('Starting Heat ReST API on %s:%s' % (host, port))
         server = wsgi.Server()
         server.start(app, cfg.CONF.heat_api, default_port=port)
+        notify.startup_notify(cfg.CONF.onready)
         server.wait()
     except RuntimeError as e:
         sys.exit("ERROR: %s" % e)

bin/heat-api-cfn

@@ -42,6 +42,7 @@ from oslo.config import cfg
 
 from heat.common import config
 from heat.common import wsgi
+from heat.common import notify
 
 from heat.openstack.common import log as logging
 
@@ -64,6 +65,7 @@ if __name__ == '__main__':
         LOG.info('Starting Heat API on %s:%s' % (host, port))
         server = wsgi.Server()
         server.start(app, cfg.CONF.heat_api_cfn, default_port=port)
+        notify.startup_notify(cfg.CONF.onready)
         server.wait()
     except RuntimeError as e:
         sys.exit("ERROR: %s" % e)

bin/heat-api-cloudwatch

@@ -42,6 +42,7 @@ from oslo.config import cfg
 
 from heat.common import config
 from heat.common import wsgi
+from heat.common import notify
 
 from heat.openstack.common import log as logging
 
@@ -64,6 +65,7 @@ if __name__ == '__main__':
         LOG.info('Starting Heat CloudWatch API on %s:%s' % (host, port))
         server = wsgi.Server()
         server.start(app, cfg.CONF.heat_api_cloudwatch, default_port=port)
+        notify.startup_notify(cfg.CONF.onready)
         server.wait()
     except RuntimeError as e:
         sys.exit("ERROR: %s" % e)

bin/heat-engine

@@ -41,6 +41,8 @@ gettextutils.install('heat', lazy=True)
 
 from oslo.config import cfg
 
+from heat.common import notify
+
 from heat.openstack.common import log as logging
 from heat.openstack.common import service
 
@@ -64,4 +66,5 @@ if __name__ == '__main__':
 
     srv = engine.EngineService(cfg.CONF.host, rpc_api.ENGINE_TOPIC)
     launcher = service.launch(srv)
+    notify.startup_notify(cfg.CONF.onready)
     launcher.wait()

etc/heat/heat.conf.sample

@@ -58,6 +58,14 @@
 # stack locking. (integer value)
 #engine_life_check_timeout=2
 
+# onready allows you to send a notification when the heat
+# processes are ready to serve.  This is either a module with
+# the notify() method or a shell command.  To enable
+# notifications with systemd, one may use the 'systemd-notify
+# --ready' shell command or the 'heat.common.systemd'
+# notification module. (string value)
+#onready=<None>
+
 # Name of the engine node. This can be an opaque identifier.
 # It is not necessarily a hostname, FQDN, or IP address.
 # (string value)

heat/common/config.py

@@ -118,7 +118,14 @@ engine_opts = [
     cfg.IntOpt('engine_life_check_timeout',
                default=2,
                help=_('RPC timeout for the engine liveness check that is used'
-                      ' for stack locking.'))]
+                      ' for stack locking.')),
+    cfg.StrOpt('onready',
+               help=_('onready allows you to send a notification when the'
+                      ' heat processes are ready to serve.  This is either a'
+                      ' module with the notify() method or a shell command. '
+                      ' To enable notifications with systemd, one may use'
+                      ' the \'systemd-notify --ready\' shell command or'
+                      ' the \'heat.common.systemd\' notification module.'))]
 
 rpc_opts = [
     cfg.StrOpt('host',

heat/common/notify.py

@@ -0,0 +1,38 @@
+# Copyright 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.
+
+"""
+Startup notification using a shell script or systemd NOTIFY_SOCKET
+style notification
+"""
+
+from heat.openstack.common import log as logging
+from heat.openstack.common import importutils
+from heat.openstack.common import processutils
+
+logger = logging.getLogger(__name__)
+
+
+def startup_notify(notify_param):
+    if not notify_param or notify_param == "":
+        return
+    try:
+        notifier = importutils.import_module(notify_param)
+    except ImportError:
+        try:
+            processutils.execute(notify_param, shell=True)
+        except Exception as e:
+            logger.error(_('Failed to execute onready command: %s') % str(e))
+    else:
+        notifier.notify()

heat/common/systemd.py

@@ -0,0 +1,44 @@
+# Copyright 2012 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 start-up completion notification.
+Used for "onready" configuration parameter in heat.conf
+"""
+
+import os
+import socket
+
+from heat.openstack.common import log as logging
+
+logger = logging.getLogger(__name__)
+
+
+def _sd_notify(msg):
+    sysd = os.getenv('NOTIFY_SOCKET')
+    if sysd:
+        sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+        if sysd.startswith('@'):
+            # abstract namespace socket
+            sysd = '\0%s' % sysd[1:]
+        sock.connect(sysd)
+        sock.sendall(msg)
+        sock.close()
+    else:
+        logger.warning(_('Unable to notify systemd of startup completion:'
+                         ' NOTIFY_SOCKET not set'))
+
+
+def notify():
+    _sd_notify('READY=1')