Installation
============

Requirements
------------

Defernia is made with several open source softwares. Defernia depends on the
following softwares:

Python_ 2.6--2.7 or PyPy_ 1.5+
   The Defernia system is mostly written in Python_ programming language.
   There's big incompatibility between Python 2.x and Python 3.x, so you
   must not use Python 3.0 nor more.

   It works on PyPy_ 1.5+ as well.

PostgreSQL_ 8.3+ or SQLite_ 3+
   Defernia uses :abbr:`RDBMS (relational databases)` to store data.
   Recommend PostgreSQL_ for production use and SQLite_ for development-purpose.

   .. note::

      It probably works well on MySQL_ also, but we don't recommend it.

Any other many Python packages
   Defernia depends on any other many Python packages listed following,
   but you can be free from these libraries. Because these libraries are
   installed automatically.

   - Mercurial_
   - SQLAlchemy_
   - Flask_ (Werkzeug_ and Jinja_)

.. note::
   
   **How to install the above softwares from Debian/Ubuntu Linux**:

   .. sourcecode:: console

      $ apt-get install python postgresql  # production
      $ apt-get install python sqlite3     # development

.. _Python: http://www.python.org/
.. _PyPy: http://pypy.org/
.. _PostgreSQL: http://www.postgresql.org/
.. _SQLite: http://www.sqlite.org/
.. _MySQL: http://www.mysql.com/
.. _Mercurial: http://mercurial.selenic.com/
.. _SQLAlchemy: http://www.sqlalchemy.org/
.. _Flask: http://flask.pocoo.org/
.. _Werkzeug: http://werkzeug.pocoo.org/
.. _Jinja: http://jina.pocoo.org/


Easy way
--------

The easiest way to install Defernia is just using pip_. It downloads Defernia
itself and resolves dependencies also automatically.

.. sourcecode:: console

   $ pip install hg+https://bitbucket.org/dahlia/defernia

.. _pip: http://www.pip-installer.org/


Hard way
--------

Defernia is an ordinary Python package that follows the standard Python
distribution way. It means that you can download the Defernia source code and
install it by yourself.

.. sourcecode:: console

   $ hg clone https://bitbucket.org/dahlia/defernia
   $ cd defernia/
   defernia$ python setup.py install

If setuptools_ or Distribute_ is installed in your system, :file:`setup.py`
must have resolved its dependencies automatically as well.

.. _setuptools: http://peak.telecommunity.com/DevCenter/setuptools
.. _Distribute: http://packages.python.org/distribute/


.. _using-virtualenv:

Using virtualenv_
-----------------

If you have an idea to develop Defernia (and contribute to it), virtualenv_
would be helpful. It helps to isolate the working Python site-packages
environemt from the system global site-packages environment. If there's no
installed :program:`virtualenv` command in your system yet, install it first:
(It might need a system administrator permission: use :command:`sudo` then.)

.. sourcecode:: console

   $ easy_install virtualenv

.. note::

   Most of Linux distributions provide :program:`virtualenv` as package.
   For example, in Debian or Ubuntu like APT-based distributions you can
   install it like:

   .. sourcecode:: console

      $ apt-get install python-virtualenv

And then, make your isolated environment for Defernia development via
:program:`virtualenv`:

.. sourcecode:: console

   $ virtualenv --distribute defernia-env
   defernia-env$ cd defernia-env/
   (defernia-env)defernia-env$ source bin/activate

The last command makes your command line prompt to enter the created
:file:`defernia-env` enviroment. The ``(defernia-env)`` prefix indicates where
you are in. When you want to back from here, type :program:`deactivate`
in the prompt.

What you have to do next is to checkout the Defernia source code.

.. sourcecode:: console

   (defernia-env)defernia-env$ hg clone https://bitbucket.org/dahlia/defernia
   (defernia-env)defernia-env$ cd defernia/

To install Defernia in development mode and resolve the dependencies,
use :program:`setup.py develop` subcommand instead of
:program:`setup.py install`.

.. sourcecode:: console

   (defernia-env)defernia$ python setup.py develop

It's finished. Now you can hack the Defernia system.

.. note::

   :program:`hg` is a command provided by Mercurial_.

.. _Mercurial: http://mercurial.selenic.com/
.. _virtualenv: http://www.virtualenv.org/