Adding applications dynamically
===============================

NOTE: this is not the best approach for hosting multiple applications. You'd better to run a uWSGI instance for each app.

You can start the uWSGI server without configuring an application.

To load a new application you can use these variables in the uwsgi packet:

* ``UWSGI_SCRIPT`` -- pass the name of a WSGI script defining an ``application`` callable
* or ``UWSGI_MODULE`` and ``UWSGI_CALLABLE`` -- the module name (importable path) and the name of the callable to invoke from that module

Dynamic apps are officially supported on Cherokee, Nginx, Apache, cgi_dynamic.
They are easily addable to the Tomcat and Twisted handlers.

Defining VirtualEnv with dynamic apps
-------------------------------------

Virtualenvs are based on the ``Py_SetPythonHome()`` function. This function has
effect only if called before ``Py_Initialize()`` so it can't be used with
dynamic apps.

To define a VirtualEnv with DynamicApps, a hack is the only solution.

First you have to tell python to not import the ``site`` module. This module
adds all ``site-packages`` to ``sys.path``.  To emulate virtualenvs, we must
load the site module only after subinterpreter initialization.  Skipping the
first ``import site``, we can now simply set ``sys.prefix`` and
``sys.exec_prefix`` on dynamic app loading and call

.. code-block:: c

   PyImport_ImportModule("site");
   // Some users would want to not disable initial site module loading, so the site module must be reloaded:
   PyImport_ReloadModule(site_module);

Now we can set the VirtualEnv dynamically using the ``UWSGI_PYHOME`` var:


.. code-block:: c

   location / {
     uwsgi_pass 192.168.173.5:3031;
     include uwsgi_params;
     uwsgi_param UWSGI_SCRIPT mytrac;
     uwsgi_param UWSGI_PYHOME /Users/roberto/uwsgi/VENV2;
   }