aodh/doc/source/install/mod_wsgi.rst
Mehdi Abaakouk 09a2f0994f Use werkzeug to run the developement API server
wsgi.simple_server in a mono threaded process that can handle only
5 requests at a time.

Even the doc recommands to setup Ceilometer through an other WSGI services
like Apache 'mod_wsgi', we can provide a better testing API server.

So this patch changes the default HTTP server to the werkzeug one with
a autodiscovery of number of workers that we can use.

The client queue of werkzeug is 128, so on a 4 cpus machine, ceilometer-api
can now handle 512 connections instead of 5.

Also the change adds references of how to deploy pecan application in
the documentation.

The config option enable_reverse_dns_lookup can be safely removed,
because werkzeug doesn't do any reverse dns lookup.

DocImpact: configuration options changed:
enable_reverse_dns_lookup removed, api_workers added

Change-Id: If7450b393ea88bc185e5c82b706ace9c38ce350e
2015-02-11 07:25:24 +01:00

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..
Copyright 2013 New Dream Network, LLC (DreamHost)
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.
====================================
Installing the API Behind mod_wsgi
====================================
Ceilometer comes with a few example files for configuring the API
service to run behind Apache with ``mod_wsgi``.
app.wsgi
========
The file ``ceilometer/api/app.wsgi`` sets up the V2 API WSGI
application. The file is installed with the rest of the ceilometer
application code, and should not need to be modified.
etc/apache2/ceilometer
======================
The ``etc/apache2/ceilometer`` file contains example settings that
work with a copy of ceilometer installed via devstack.
.. literalinclude:: ../../../etc/apache2/ceilometer
1. Copy or symlink the file to ``/etc/apache2/sites-avilable``.
2. Modify the ``VirtualHost`` directive, setting a hostname or IP for
the service. The default settings assume that the ceilometer API is
the only service running on the local Apache instance, which
conflicts with Horizon's default configuration.
3. Modify the ``WSGIDaemonProcess`` directive to set the
``user`` and ``group`` values to a user available on your server.
4. Modify the ``APACHE_RUN_USER`` and ``APACHE_RUN_GROUP`` values to
the name of a user and group available on your server.
5. Enable the ceilometer site.
::
$ a2ensite ceilometer
$ service apache2 reload
Limitation
==========
As Ceilometer is using Pecan and Pecan's DebugMiddleware doesn't support
multiple processes, there is no way to set debug mode in the multiprocessing
case. To allow multiple processes the DebugMiddleware may be turned off by
setting ``pecan_debug`` to ``False`` in the ``api`` section of
``ceilometer.conf``.
For other WSGI setup you can refer to the `pecan deployement`_ documentation.
.. _`pecan deployement`: http://pecan.readthedocs.org/en/latest/deployment.html#deployment