Authors:

• Patrick Hetu patrick.hetu@gmail.com
• Bruno Girin

Django is a high-level web application framework that loosely follows the model-view-controller design pattern. Python's equivalent to Ruby on Rails, Django lets you build complex data-driven websites quickly and easily - Django focuses on automating as much as possible and adhering to the "Don't Repeat Yourself" (DRY) principle. Django additionally emphasizes reusability and "pluggability" of components; many generic third-party "applications" are available to enhance projects or to simply to reduce development time even further.

Notable features include:

• An object-relational mapper (ORM)
• Automatic admin interface
• Elegant URL dispatcher
• Form serialization and validation system
• Templating system
• Lightweight, standalone web server for development and testing
• Internationalization support
• Testing framework and client

This charm will install Django. It can also install your Django project and his dependencies from either a template or from a version control system.

It can also link your project to a database and sync the schemas. This charm also come with a Fabric fabfile to interact with the deployement in a cloud aware manner.

Simply::

juju bootstrap
juju deploy python-django

juju deploy postgresql
juju add-relation python-django postgresql:db

juju deploy gunicorn
juju add-relation python-django gunicorn
juju expose python-django

In a couple of minute, your new (vanilla) Django site should be ready at the public address of gunicorn. You can find it in the output of the juju status command.

This is roughtly equivalent to the Creating a project step in Django's tutorial.

1. Setup your Django specific parameters in mydjangosite.yaml like this one::

   mydjangosite: project_template_url: https://github.com/xenith/django-base-template/zipball/master project_template_extension: py,md,rst

Note: If your using juju-core you must remove the first line of the file and the indentation for the rest of the file.

1. Deployment with Gunicorn::

   juju bootstrap juju deploy --config mydjangosite.yaml mydjangosite

   juju deploy postgresql juju add-relation mydjangosite postgresql:db

   juju deploy gunicorn juju add-relation mydjangosite gunicorn juju expose mydjangosite

1. Setup your Django specific parameters in mydjangosite.yaml like this one::

   mydjangosite: vcs: bzr repos_url: lp:~patrick-hetu/my_site

Note:

If your using juju-core you must remove the first line of the file and the indentation for the rest of the file.

1. Deployment with Gunicorn::

    juju bootstrap
    juju deploy --config mydjangosite.yaml python-django
   
    juju deploy postgresql
    juju add-relation python-django postgresql:db
   
    juju deploy gunicorn
    juju add-relation python-django gunicorn
    juju expose python-django
   

Note: If your using juju-core you must add --upload-tools to the juju bootstrap command.

1. Accessing your new Django site should be ready at the public address of Gunicorn. To find it look for it in the output of the juju status command.

Taking the previous example, your web site should be on the Django node at:

/srv/python-django/

As you can see there the charm have inject some code at the end of your settings.py file (or created it if it was not there) to be able to import what's in the juju_settings/ directory.

It's recommended to make your vcs to ignore database and secret files or any files that have information that you don't want to be publish.

This charm allow you to upgrade your deployment using the Juju's upgrade-charm command. This command will:

• upgrade Django
• upgrade additionnal pip packages
• upgrade additionnal Debian packages
• upgrade using requirements files in your project

Fabric is a Python (2.5 or higher) library and command-line tool for streamlining the use of SSH for application deployment or systems administration tasks.

It provides a basic suite of operations for executing local or remote shell commands (normally or via sudo) and uploading/downloading files, as well as auxiliary functionality such as prompting the running user for input, or aborting execution.

This charm includes a Fabric script that use Juju's information to perform various tasks.

For a list of tasks type this command after bootstraping your Juju environment::

fab -l

For example, with a python-django service deployed you can run commands on all its units::

fab -R python-django pull
[10.0.0.2] Executing task 'pull'
[10.0.0.2] run: bzr pull lp:~my_name/django_code/my_site
...
[10.0.0.2] run: invoke-rc.d gunicorn restart
...

Or you can also run commands on a single unit::

fab -R python-django/0 manage:createsuperuser
...
[10.0.0.2] out: Username (leave blank to use 'ubuntu'):

Limitation:

• You can only execute task for one role at the time. But it can be a service or unit.

If you want to extend the fabfile check out fabtools.

Note that if your using a requirement.txt file the packages will be downloaded with pip and it doesn't do any cryptographic verification of its downloads.

To create an application subordinate charm that can be related to this charm you need at least to define an interface named directory-path in your metadate.yaml file like this::

[...] requires: python-django: interface: directory-path scope: container optional: true

When you will add a relation between your charm and the python-django charm the hook you will be able to get those relation variables:

• settings_dir_path
• urls_dir_path
• django_admin_cmd
• install_root

now your charm will be informed about where it need to add new settings and urls files and how to run additionnal Django commands. The Django charm reload Gunicorn after the relation to catch the changes.

• Rewrite the charm using python instead of BASH scripts
• Django projects now need no modification to work with the charm
• Use the django-admin startproject command with configurable arguments if no repos is specified
• Juju's generated settings and urls files are now added in a juju_settings and a juju_urls directories by default
• New MongoDB relation (server side is yet to be done)
• New upgrade hook that upgrade pip and debian packages
• Expose ports is now handle by the charm

Configuration changes:

• default user and group is now ubuntu
• new install_root option
• new django_version option
• new additional_pip_packages option
• new repos_branch,repos_username,repos_password options
• new project_name, project_template_extension, project_template_url options
• new urls_dir_name and settings_dir_name options
• new project_template_url and project_template_extension options
• database, uploads, static, secret and cache settings locations are now configurable
• extra_deb_pkg was renamed additional_distro_packages
• requirements was renamed requirements_pip_files and now support multiple files
• if python_path is empty set as install_root

Backwards incompatible changes:

• swift support was moved to a subordinate charm
• postgresql relation hook was rename pgsql instead of db

• You can configure all wsgi (Gunicorn) settings via the config.yaml file
• Juju compatible Fabric fabfile.py is included for PAAS commands
• Swift storage backend is now optional

Backwards incompatible changes:

• Use split settings and urls
• Permissons are now based on WSGI's user and group instead of just being www-data
• media and static files are now in new directories ./uploads and ./static/
• Deprecated configuration variables: site_domain, site_username, site_password, site_admin_email

• Initial release

• http://www.deploydjango.com
• http://lincolnloop.com/django-best-practices/
• https://github.com/30loops/djangocms-on-30loops.git
• https://github.com/openshift/django-example
• http://lincolnloop.com/blog/2013/feb/15/django-settings-parity-youre-doing-it-wrong/
• http://tech.yipit.com/2011/11/02/django-settings-what-to-do-about-settings-py/
• http://www.rdegges.com/the-perfect-django-settings-file/
• https://github.com/xenith/django-base-template.git
• https://github.com/transifex/transifex/blob/devel/transifex/settings.py
• http://peterlyons.com/problog/2010/02/environment-variables-considered-harmful