.. _overview:

=====================

Installation overview

=====================

Some overview and some details that can help understanding the options when

installing Kallithea.

Python environment

------------------

**Kallithea** is written entirely in Python_ and requires Python version

2.6 or higher. Python 3.x is currently not supported.

Given a Python installation, there are different ways of providing the

environment for running Python applications. Each of them pretty much

corresponds to a ``site-packages`` directory somewhere where packages can be

installed.

Kallithea itself can be run from source or be installed, but even when running

from source, there are some dependencies that must be installed in the Python

environment used for running Kallithea.

- Packages *could* be installed in Python's ``site-packages`` directory ... but

  that would require running pip_ as root and it would be hard to uninstall or

  upgrade and is probably not a good idea unless using a package manager.

- Packages could also be installed in ``~/.local`` ... but that is probably

  only a good idea if using a dedicated user per application or instance.

- Finally, it can be installed in a virtualenv_. That is a very lightweight

  "container" where each Kallithea instance can get its own dedicated and

  self-contained virtual environment.

We recommend using virtualenv for installing Kallithea.

Installation methods

--------------------

Kallithea must be installed on a server. Kallithea is installed in a Python

environment so it can use packages that are installed there and make itself

available for other packages.

Two different cases will pretty much cover the options for how it can be

installed.

- The Kallithea source repository can be cloned and used -- it is kept stable and

  can be used in production. The Kallithea maintainers use the development

  branch in production. The advantage of installation from source and regularly

  updating it is that you take advantage of the most recent improvements. Using

  it directly from a DVCS also means that it is easy to track local customizations.

  Running ``pip install -e .`` in the source will use pip to install the

  necessary dependencies in the Python environment and create a

  ``.../site-packages/Kallithea.egg-link`` file there that points at the Kallithea

  source.

- Kallithea can also be installed from ready-made packages using a package manager.

  The official released versions are available on PyPI_ and can be downloaded and

  installed with all dependencies using ``pip install kallithea``.

  With this method, Kallithea is installed in the Python environment as any

  other package, usually as a ``.../site-packages/Kallithea-X-py2.7.egg/``

  directory with Python files and everything else that is needed.

  (``pip install kallithea`` from a source tree will do pretty much the same

  but build the Kallithea package itself locally instead of downloading it.)

.. note::

   Kallithea includes front-end code that needs to be processed first.

   The tool npm_ is used to download external dependencies and orchestrate the

   processing. The ``npm`` binary must thus be available.

Web server

----------

Kallithea is (primarily) a WSGI_ application that must be run from a web

server that serves WSGI applications over HTTP.

Kallithea itself is not serving HTTP (or HTTPS); that is the web server's

responsibility. Kallithea does however need to know its own user facing URL

(protocol, address, port and path) for each HTTP request. Kallithea will

usually use its own HTML/cookie based authentication but can also be configured

to use web server authentication.

There are several web server options:

- Kallithea uses the Gearbox_ tool as command line interface. Gearbox provides

  ``gearbox serve`` as a convenient way to launch a Python WSGI / web server

  from the command line. That is perfect for development and evaluation.

  Actual use in production might have different requirements and need extra

  work to make it manageable as a scalable system service.

  Gearbox comes with its own built-in web server but Kallithea defaults to use

  Waitress_. Gunicorn_ is also an option. These web servers have different

  limited feature sets.

  The web server used by ``gearbox`` is configured in the ``.ini`` file passed

  to it. The entry point for the WSGI application is configured

  in ``setup.py`` as ``kallithea.config.middleware:make_app``.

- `Apache httpd`_ can serve WSGI applications directly using mod_wsgi_ and a

  simple Python file with the necessary configuration. This is a good option if

  Apache is an option.

- uWSGI_ is also a full web server with built-in WSGI module.

- IIS_ can also server WSGI applications directly using isapi-wsgi_.

- A `reverse HTTP proxy <https://en.wikipedia.org/wiki/Reverse_proxy>`_

  can be put in front of another web server which has WSGI support.

  Such a layered setup can be complex but might in some cases be the right

  option, for example to standardize on one internet-facing web server, to add

  encryption or special authentication or for other security reasons, to

  provide caching of static files, or to provide load balancing or fail-over.

  Nginx_, Varnish_ and HAProxy_ are often used for this purpose, often in front

  of a ``gearbox serve`` that somehow is wrapped as a service.

The best option depends on what you are familiar with and the requirements for

performance and stability. Also, keep in mind that Kallithea mainly is serving

dynamically generated pages from a relatively slow Python process. Kallithea is

also often used inside organizations with a limited amount of users and thus no

continuous hammering from the internet.

.. _Python: http://www.python.org/

.. _Gunicorn: http://gunicorn.org/

.. _Waitress: http://waitress.readthedocs.org/en/latest/

.. _virtualenv: http://pypi.python.org/pypi/virtualenv

.. _Gearbox: http://turbogears.readthedocs.io/en/latest/turbogears/gearbox.html

.. _PyPI: https://pypi.python.org/pypi

Additional tutorial

http://pylonsbook.com/en/1.1/deployment.html#using-apache-to-proxy-requests-to-pylons

.. _apache_subdirectory:

Apache as subdirectory

----------------------

Apache subdirectory part:

.. code-block:: apache

    <Location /PREFIX >

      ProxyPass http://127.0.0.1:5000/PREFIX

      ProxyPassReverse http://127.0.0.1:5000/PREFIX

      SetEnvIf X-Url-Scheme https HTTPS=1

    </Location>

Besides the regular apache setup you will need to add the following line

into ``[app:main]`` section of your .ini file::

    filter-with = proxy-prefix

Add the following at the end of the .ini file::

    [filter:proxy-prefix]

    use = egg:PasteDeploy#prefix

    prefix = /PREFIX

then change ``PREFIX`` into your chosen prefix

.. _apache_mod_wsgi:

Apache with mod_wsgi

--------------------

Alternatively, Kallithea can be set up with Apache under mod_wsgi. For

that, you'll need to:

- Install mod_wsgi. If using a Debian-based distro, you can install

  the package libapache2-mod-wsgi::

    aptitude install libapache2-mod-wsgi

- Enable mod_wsgi::

    a2enmod wsgi

- Add global Apache configuration to tell mod_wsgi that Python only will be

  used in the WSGI processes and shouldn't be initialized in the Apache

  processes::

    WSGIRestrictEmbedded On

- Create a WSGI dispatch script, like the one below. Make sure you

  check that the paths correctly point to where you installed Kallithea

  and its Python Virtual Environment.

  .. code-block:: python

      import os

      os.environ['PYTHON_EGG_CACHE'] = '/srv/kallithea/.egg-cache'

      # sometimes it's needed to set the current dir

      os.chdir('/srv/kallithea/')

      import site

      site.addsitedir("/srv/kallithea/venv/lib/python2.7/site-packages")

      ini = '/srv/kallithea/my.ini'

      from logging.config import fileConfig

      fileConfig(ini)

      from paste.deploy import loadapp

      application = loadapp('config:' + ini)

  Or using proper virtualenv activation:

  .. code-block:: python

      activate_this = '/srv/kallithea/venv/bin/activate_this.py'

      execfile(activate_this, dict(__file__=activate_this))

      import os

      os.environ['HOME'] = '/srv/kallithea'

      ini = '/srv/kallithea/kallithea.ini'

      from logging.config import fileConfig

      fileConfig(ini)

      from paste.deploy import loadapp

      application = loadapp('config:' + ini)

- Add the necessary ``WSGI*`` directives to the Apache Virtual Host configuration

  file, like in the example below. Notice that the WSGI dispatch script created

  above is referred to with the ``WSGIScriptAlias`` directive.

  Apache will by default run as a special Apache user, on Linux systems

  usually ``www-data`` or ``apache``. If you need to have the repositories

  directory owned by a different user, use the user and group options to

  WSGIDaemonProcess to set the name of the user and group.

  Once again, check that all paths are correctly specified.

  .. code-block:: apache

      WSGIDaemonProcess kallithea processes=5 threads=1 maximum-requests=100 \

      WSGIProcessGroup kallithea

      WSGIScriptAlias / /srv/kallithea/dispatch.wsgi

      WSGIPassAuthorization On

  Or if using a dispatcher WSGI script with proper virtualenv activation:

  .. code-block:: apache

      WSGIProcessGroup kallithea

      WSGIScriptAlias / /srv/kallithea/dispatch.wsgi

      WSGIPassAuthorization On

Other configuration files

-------------------------

A number of `example init.d scripts`__ can be found in

the ``init.d`` directory of the Kallithea source.

.. __: https://kallithea-scm.org/repos/kallithea/files/tip/init.d/ .

.. _virtualenv: http://pypi.python.org/pypi/virtualenv

.. _python: http://www.python.org/

.. _Python regular expression documentation: https://docs.python.org/2/library/re.html

.. _Mercurial: https://www.mercurial-scm.org/

.. _Celery: http://celeryproject.org/

.. _Celery documentation: http://docs.celeryproject.org/en/latest/getting-started/index.html

.. _RabbitMQ: http://www.rabbitmq.com/

.. _Redis: http://redis.io/

.. _mercurial-server: http://www.lshift.net/mercurial-server.html

.. _PublishingRepositories: https://www.mercurial-scm.org/wiki/PublishingRepositories