Kafka healthcheck

This commit provides healthcheck package for
monasca-common where so called checks can be defined
and used throughout monasca-* projects.

Summary:
- KafkaHealthCheck
- HealthCheckResult

Change-Id: Ib404ae128c8a3c93b24e4e237a3d77130fb18b53

monasca_common/healthcheck/checks/kafka.py

@@ -0,0 +1,103 @@
+# Copyright 2016 FUJITSU LIMITED
+#
+# 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.
+
+from kafka import client
+from oslo_config import cfg
+from oslo_log import log
+
+from monasca_common.healthcheck import result
+
+LOG = log.getLogger(__name__)
+CONF = cfg.CONF
+
+kafka_check_opts = [
+    cfg.StrOpt('kafka_url',
+               required=True,
+               help='Url to kafka server'),
+    cfg.ListOpt('kafka_topics',
+                required=True,
+                default=['logs'],
+                help='Verify existence of configured topics')
+]
+kafka_check_group = cfg.OptGroup(name='kafka_healthcheck',
+                                 title='kafka_healthcheck')
+
+cfg.CONF.register_group(kafka_check_group)
+cfg.CONF.register_opts(kafka_check_opts, kafka_check_group)
+
+
+class KafkaHealthCheck(object):
+    """Evaluates kafka health
+
+    Healthcheck verifies if:
+
+    * kafka server is up and running
+    * there is a configured topic in kafka
+
+    If following conditions are met healthcheck returns healthy status.
+    Otherwise unhealthy status is returned with explanation.
+
+     Example of middleware configuration:
+
+    .. code-block:: ini
+
+      [kafka_healthcheck]
+      kafka_url = localhost:8900
+      kafka_topics = log
+
+    Note:
+        It is possible to specify multiple topics if necessary.
+        Just separate them with ,
+
+    """
+
+    def healthcheck(self):
+        url = CONF.kafka_healthcheck.kafka_url
+
+        try:
+            kafka_client = client.KafkaClient(hosts=url)
+        except client.KafkaUnavailableError as ex:
+            LOG.error(repr(ex))
+            error_str = 'Could not connect to kafka at %s' % url
+            return result.HealthCheckResult(healthy=False, message=error_str)
+
+        self._disconnect_gracefully(kafka_client)
+
+        return self._verify_topics(kafka_client)
+
+    # noinspection PyMethodMayBeStatic
+    def _verify_topics(self, kafka_client):
+        topics = CONF.kafka_healthcheck.kafka_topics
+
+        for t in topics:
+            # kafka client loads metadata for topics as fast
+            # as possible (happens in __init__), therefore this
+            # topic_partitions is sure to be filled
+            for_topic = t in kafka_client.topic_partitions
+            if not for_topic:
+                error_str = 'Kafka: Topic %s not found' % t
+                LOG.error(error_str)
+                return result.HealthCheckResult(healthy=False, message=error_str)
+
+        return result.HealthCheckResult(healthy=True, message='OK')
+
+    # noinspection PyMethodMayBeStatic
+    def _disconnect_gracefully(self, kafka_client):
+        # at this point, client is connected so it must be closed
+        # regardless of topic existence
+        try:
+            kafka_client.close()
+        except Exception as ex:
+            # log that something went wrong and move on
+            LOG.error(repr(ex))

monasca_common/healthcheck/result.py

@@ -0,0 +1,19 @@
+# Copyright 2016 FUJITSU LIMITED
+#
+# 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 collections
+
+HealthCheckResult = collections.namedtuple('CheckResult',
+                                           ['healthy', 'message'])
+"""Result from the healthcheck, contains healthy(boolean) and message"""