Request for comments on a new Open Source Paas platform for Django

Hi,

I'm building a Juju based Open Source Paas platform for Django and

I need your help because it is a hard task to make a PAAS system

that is flexible enough to deploy any projects and at the same time

simple to use.

For the ones that don't know Juju, it's a service orchestration software

compatible with LXC (local), EC2, HPCloud, OpenStack and Baremetal/Maas

developed by Canonical (the company that makes Ubuntu).

Check out the web site for more details: https://juju.ubuntu.com/

So quickly, here's how it would works:

After installing Juju and configuring it with for your favourite cloud provider you

will need to create a configuration file in the YAML format named my_django_conf.yaml

in this example::

  my_django_site:

      vcs: git

      repos_url: https://github.com/my_username/my_site.git 

      site_secret_key: abcdefgh123456789

      use_virtualenv: True

Then you will need these commands to bootstrap and launch all the servers::

  juju bootstrap

  juju deploy --config my_django_conf.yaml my_django_site

  juju deploy postgresql # or mysql,mongodb, etc

  juju deploy gunicorn # Or mod_wsgi, etc

  juju add-relation my_django_site postgresql

  juju add-relation my_django_site gunicorn

  juju expose gunicorn # Open the tcp port in the firewall

You will end up with 3 servers running. One will be the controller

and one for each service (django and the database). 

Gunicorn will be a special charm that will be installed on your Django server.

After that, adding a new Django node would be as simple as::

  juju add-unit my_django_site

As I said, where it gets tricky is how do I make the configuration flexible enough

and at the same time simple.

After looking at what was existing in Django's Paas world, I came with this:

1 - We need a configurable requirements files for both pip and apt-get. By default

it would be looking for package in there files at install time::

  requirements_pip_files: requirements.txt,requirements.pip

  requirements_apt_files: requirements.apt

and we could also configure extra packages by adding variables like this in the YAML file::

  additional_distro_packages: vim,emacs,etc

  additional_pip_packages: virtualenvwrapper,celery,South,etc

2 - I'm suggesting to use separate configurations files in a settings/ directory

so by default it will be injecting configuration in those files::

    settings_database_path: settings/20-engine.py

    settings_static_path: settings/20-static.py

    settings_uploads_path: settings/20-media.py

    settings_cache_path: settings/30-cache.py

    settings_secret_key_path: settings/20-secret.py

I'm suggesting splitting settings because when the configuration is modified,

for some reason, it would be difficult and risky to parse settings.py and 

change only the right thing.

So instead, I would be using topic files rendered with templates.

So if you would need to do more advanced stuff you could just fork the charm

and modify the templates for your needs.

3 - Finally, I was thinking adding some options to execute custom scripts that

would run a various time during the deployment. Like after packages installation

,database configuration and static file configuration::

    post_database_script:

        type: string

        default: |

          #!/bin/sh

          python manage.py syncdb --noinput

          python manage.py migrate --noinput

    post_static_script:

        type: string

        default: |

          #!/bin/sh

          python manage.py collectstatic -v 0 --noinput

Note that this is not making unanimity so far.

There is several reasons that makes the scripts approach tricky:

* You don't want to execute these scripts every time a little detail change.

* You might need the database configuration to be ready for some script.

* You could be not using south

* You might want to import some initial data and maybe only once at install time.

* You could want to compress static files after running collectstatic

* etc

An other idea could be to use a Fabric plug-in that use Juju's database to connect

to the machines and run commands like this for example::

  fab -R my_django_site python manage.py pull

would pull the latest version of the site and reload the application on every

deployed Django machines.

The bottom line here is that it's not simple to find out what a standard

Django deployment (and is maintenance) looks like.

That being said, I'm really looking forwards for you comments and suggestions.

Patrick

--
You received this message because you are subscribed to the Google Groups "Django users" group.
To unsubscribe from this group and stop receiving emails from it, send an email to django-users+unsubscribe@googlegroups.com.
To post to this group, send email to django-users@googlegroups.com.
Visit this group at http://groups.google.com/group/django-users?hl=en.
For more options, visit https://groups.google.com/groups/opt_out.