Team and repository tags
========================

.. image:: https://governance.openstack.org/tc/badges/monasca-persister.svg
    :target: https://governance.openstack.org/tc/reference/tags/index.html

.. Change things from this point on

monasca-persister
=================

The Monitoring Persister consumes metrics and alarm state transitions
from the Message Queue and stores them in the Metrics and Alarms
database.

Although the Persister isn't primarily a Web service it uses DropWizard,
https://dropwizard.github.io/dropwizard/, which provides a nice Web
application framework to expose an http endpoint that provides an
interface through which metrics about the Persister can be queried as
well as health status.

The basic design of the Persister is to have one Kafka consumer publish
to a Disruptor, https://github.com/LMAX-Exchange/disruptor, that has
output processors. The output processors use prepared batch statements
to write to the Metrics and Alarms database.

The number of output processors/threads in the Persister can be
specified to scale to more messages. To horizontally scale and provide
fault-tolerance any number of Persisters can be started as consumers
from the Message Queue.

Build
=====

Requires monasca-common from
https://github.com/openstack/monasca-common. Download and build
following instructions in its README.md. Then build monasca-persister
by:

::

   mvn clean package

Configuration
=============

A sample configuration file is available in
java/src/deb/etc/persister-config.yml-sample.

A second configuration file is provided in
java/src/main/resources/persister-config.yml for use with the `vagrant
"mini-mon" development environment`_.

TODO
====

-  Purge metrics on shutdown
-  Add more robust offset management in Kafka. Currently, the offset is
   advanced as each message is read. If the Persister stops after the
   metric has been read and prior to it being committed to the Metrics
   and Alarms database, the metric will be lost.
-  Add better handling of SQL exceptions.
-  Complete health check.
-  Specify and document the names of the metrics that are available for
   monitoring of the Persister.
-  Document the yaml configuration parameters.

License
=======

Copyright (c) 2014 Hewlett-Packard Development Company, L.P.

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.

Python
======

To install the Python monasca-persister modules, git clone the source
and run the following command:

::

   $ sudo python setup.py install

To run the unit tests use:

::

   $ tox -e py27,py35

.. _vagrant "mini-mon" development environment: https://github.com/openstack/monasca-vagrant/
