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Deploy behind HAProxy
=====================
This guide demonstrates a way to load balance connections across multiple
websockets server processes running on the same machine with HAProxy_.
We'll run server processes with Supervisor as described in :doc:`this guide
<supervisor>`.
Run server processes
--------------------
Save this app to ``app.py``:
.. literalinclude:: ../../example/deployment/haproxy/app.py
:emphasize-lines: 24
Each server process listens on a different port by extracting an incremental
index from an environment variable set by Supervisor.
Save this configuration to ``supervisord.conf``:
.. literalinclude:: ../../example/deployment/haproxy/supervisord.conf
This configuration runs four instances of the app.
Install Supervisor and run it:
.. code-block:: console
$ supervisord -c supervisord.conf -n
Configure and run HAProxy
-------------------------
Here's a simple HAProxy configuration to load balance connections across four
processes:
.. literalinclude:: ../../example/deployment/haproxy/haproxy.cfg
In the backend configuration, we set the load balancing method to
``leastconn`` in order to balance the number of active connections across
servers. This is best for long running connections.
Save the configuration to ``haproxy.cfg``, install HAProxy, and run it:
.. code-block:: console
$ haproxy -f haproxy.cfg
You can confirm that HAProxy proxies connections properly:
.. code-block:: console
> Hello!
< Hello!
Connection closed: 1000 (OK).