Versioned Notifications for service object

Implements: blueprint service-versioned-notifications-api

Change-Id: I9d601edb265ee230104f6c63a5f044869aeb3a02

watcher/api/scheduling.py

@@ -0,0 +1,99 @@
+# -*- encoding: utf-8 -*-
+# Copyright (c) 2017 Servionica
+#
+# 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.
+
+
+import datetime
+from oslo_config import cfg
+from oslo_log import log
+from oslo_utils import timeutils
+import six
+
+from watcher._i18n import _LW
+from watcher.common import context as watcher_context
+from watcher.common import scheduling
+from watcher import notifications
+
+from watcher import objects
+
+CONF = cfg.CONF
+LOG = log.getLogger(__name__)
+
+
+class APISchedulingService(scheduling.BackgroundSchedulerService):
+
+    def __init__(self, gconfig=None, **options):
+        self.services_status = {}
+        gconfig = None or {}
+        super(APISchedulingService, self).__init__(gconfig, **options)
+
+    def get_services_status(self, context):
+        services = objects.service.Service.list(context)
+        for service in services:
+            result = self.get_service_status(context, service.id)
+            if service.id not in self.services_status.keys():
+                self.services_status[service.id] = result
+                continue
+            if self.services_status[service.id] != result:
+                self.services_status[service.id] = result
+                notifications.service.send_service_update(context, service,
+                                                          state=result)
+
+    def get_service_status(self, context, service_id):
+        service = objects.Service.get(context, service_id)
+        last_heartbeat = (service.last_seen_up or service.updated_at
+                          or service.created_at)
+        if isinstance(last_heartbeat, six.string_types):
+            # NOTE(russellb) If this service came in over rpc via
+            # conductor, then the timestamp will be a string and needs to be
+            # converted back to a datetime.
+            last_heartbeat = timeutils.parse_strtime(last_heartbeat)
+        else:
+            # Objects have proper UTC timezones, but the timeutils comparison
+            # below does not (and will fail)
+            last_heartbeat = last_heartbeat.replace(tzinfo=None)
+        elapsed = timeutils.delta_seconds(last_heartbeat, timeutils.utcnow())
+        is_up = abs(elapsed) <= CONF.service_down_time
+        if not is_up:
+            LOG.warning(_LW('Seems service %(name)s on host %(host)s is down. '
+                            'Last heartbeat was %(lhb)s.'
+                            'Elapsed time is %(el)s'),
+                        {'name': service.name,
+                         'host': service.host,
+                         'lhb': str(last_heartbeat), 'el': str(elapsed)})
+            return objects.service.ServiceStatus.FAILED
+
+        return objects.service.ServiceStatus.ACTIVE
+
+    def start(self):
+        """Start service."""
+        context = watcher_context.make_context(is_admin=True)
+        self.add_job(self.get_services_status, name='service_status',
+                     trigger='interval', jobstore='default', args=[context],
+                     next_run_time=datetime.datetime.now(), seconds=60)
+        super(APISchedulingService, self).start()
+
+    def stop(self):
+        """Stop service."""
+        self.shutdown()
+
+    def wait(self):
+        """Wait for service to complete."""
+
+    def reset(self):
+        """Reset service.
+
+        Called in case service running in daemon mode receives SIGHUP.
+        """