.. _modwsgi_tutorial:
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Running a :app:`Pyramid` Application under ``mod_wsgi``
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=======================================================
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:term:`mod_wsgi` is an Apache module developed by Graham Dumpleton.
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It allows :term:`WSGI` programs to be served using the Apache web
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server.
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This guide will outline broad steps that can be used to get a :app:`Pyramid`
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application running under Apache via ``mod_wsgi``. This particular tutorial
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was developed under Apple's Mac OS X platform (Snow Leopard, on a 32-bit
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Mac), but the instructions should be largely the same for all systems, delta
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specific path information for commands and files.
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.. note:: Unfortunately these instructions almost certainly won't work for
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deploying a :app:`Pyramid` application on a Windows system using
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``mod_wsgi``. If you have experience with :app:`Pyramid` and ``mod_wsgi``
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on Windows systems, please help us document this experience by submitting
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documentation to the `Pylons-devel maillist
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<http://groups.google.com/group/pylons-devel>`_.
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#. The tutorial assumes you have Apache already installed on your
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system. If you do not, install Apache 2.X for your platform in
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whatever manner makes sense.
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#. It is also assumed that you have satisfied the
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:ref:`requirements-for-installing-packages`.
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#. Once you have Apache installed, install ``mod_wsgi``. Use the
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(excellent) `installation instructions
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<http://code.google.com/p/modwsgi/wiki/InstallationInstructions>`_
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for your platform into your system's Apache installation.
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#. Create a :term:`virtual environment` which we'll use to install our
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application.
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.. code-block:: text
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$ cd ~
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$ mkdir modwsgi
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$ cd modwsgi
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$ python3 -m venv env
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#. Install :app:`Pyramid` into the newly created virtual environment:
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.. code-block:: text
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$ cd ~/modwsgi/env
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$ $VENV/bin/pip install pyramid
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#. Create and install your :app:`Pyramid` application. For the purposes of
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this tutorial, we'll just be using the ``pyramid_starter`` application as
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a baseline application. Substitute your existing :app:`Pyramid`
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application as necessary if you already have one.
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.. code-block:: text
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$ cd ~/modwsgi/env
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$ $VENV/bin/pcreate -s starter myapp
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$ cd myapp
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$ $VENV/bin/pip install -e .
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#. Within the virtual environment directory (``~/modwsgi/env``), create a
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script named ``pyramid.wsgi``. Give it these contents:
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.. code-block:: python
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from pyramid.paster import get_app, setup_logging
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ini_path = '/Users/chrism/modwsgi/env/myapp/production.ini'
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setup_logging(ini_path)
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application = get_app(ini_path, 'main')
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The first argument to ``get_app`` is the project configuration file
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name. It's best to use the ``production.ini`` file provided by your
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scaffold, as it contains settings appropriate for
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production. The second is the name of the section within the .ini file
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that should be loaded by ``mod_wsgi``. The assignment to the name
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``application`` is important: mod_wsgi requires finding such an
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assignment when it opens the file.
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The call to ``setup_logging`` initializes the standard library's
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`logging` module to allow logging within your application.
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See :ref:`logging_config`.
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There is no need to make the ``pyramid.wsgi`` script executable.
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However, you'll need to make sure that *two* users have access to change
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into the ``~/modwsgi/env`` directory: your current user (mine is
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``chrism`` and the user that Apache will run as often named ``apache`` or
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``httpd``). Make sure both of these users can "cd" into that directory.
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#. Edit your Apache configuration and add some stuff. I happened to
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create a file named ``/etc/apache2/other/modwsgi.conf`` on my own
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system while installing Apache, so this stuff went in there.
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.. code-block:: apache
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# Use only 1 Python sub-interpreter. Multiple sub-interpreters
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# play badly with C extensions. See
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# http://stackoverflow.com/a/10558360/209039
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WSGIApplicationGroup %{GLOBAL}
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WSGIPassAuthorization On
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WSGIDaemonProcess pyramid user=chrism group=staff threads=4 \
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python-path=/Users/chrism/modwsgi/env/lib/python2.7/site-packages
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WSGIScriptAlias /myapp /Users/chrism/modwsgi/env/pyramid.wsgi
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<Directory /Users/chrism/modwsgi/env>
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WSGIProcessGroup pyramid
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Order allow,deny
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Allow from all
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</Directory>
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#. Restart Apache
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.. code-block:: text
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$ sudo /usr/sbin/apachectl restart
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#. Visit ``http://localhost/myapp`` in a browser. You should see the
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sample application rendered in your browser.
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:term:`mod_wsgi` has many knobs and a great variety of deployment
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modes. This is just one representation of how you might use it to
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serve up a :app:`Pyramid` application. See the `mod_wsgi
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configuration documentation
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<http://code.google.com/p/modwsgi/wiki/ConfigurationGuidelines>`_ for
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more in-depth configuration information.
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