Hello all,
I am still quite new to Ansible (but coming from Puppet background, so
my perspective might be a bit skewed to top it off), and I am currently
trying to figure out what would be the best way to layout roles while
attempting to apply DRY (don't repeat yourself) principles as much as
possible. Plus, I'm trying to have somewhat complex deployment with
providing as little input as possible (kind of convention over
configuration).
My current goal is to deploy one or more Django projects on a single
host/group of hosts. Currently I have the following roles:
- common - Sets-up some basic things on the OS, amongst
other things the OS users and groups. Users and groups are read from
two list variables.
- virtualenv - Sets-up Python virtual environments. Virtual
environments are read from a single list variable that includes info
about mode for files/dirs, users that should own the virtual
environment, destination directory etc.
- supervisor - Sets-up supervisor for running (in this case) one or
more WSGI applications. List of supervisor configurations (apps to
monitor) is passed via list, with each item containing info about
what user should run the command, command itself etc.
Now, the above should be mostly enough to deploy all the things
necessary for a project (bits and pieces missing, but I'm sure I can
handle those). From here, though, I am finding some issues on how to
properly encapsulate this.
For start, I do have an idea of a convention I want to apply for my
deployments. This includes specific user/group naming based on a
project name, destination directory for virtualenv etc. What I'm looking
into would be being able to pass in only a couple of values via
variables (let's say name, user and group) to my high-level role (or
perhaps playbook), and calculate the non-specified parameters (required
by roles common, virtualenv, and supervisor) from those. I would also
want to deploy multiple Django projects (this is the important part) on
the same host/group.
1. Try to create a new role, called django, which would basically
iterate over a list of projects. The problem is that I need to pass in
some relatively complex (with calculations included) structures to
roles common, virtualenv, and supervisor, and variable manipulation is a
bit limited within the yml files. I think I would probably be able to
use include directive in combination with a custom lookup plugin. I
have tried using set_fact with with_items to try to append to lists, but
that didn't work for me (only the last item from with_items got
appended).
2. Ditch the effort for DRY and separation, and simply have one
monolithic django role that'll deploy user/group, virtualenv,
supervisor etc. Still, there might be some rather similar set-ups where
I'd end-up duplicating all of the tasks and logic.
3. Instead of deploying through a single site.yml, use
deployment-specific (one-timish) playbook. I would, however, need to
somehow keep track of what Django project gets deployed where. What
would be the best way to do this with Ansible?
4. Something else someone suggests from this list 
Any recommendations on what would be the best way to proceed with this?
I'm open to all suggestions. If someone has a good link to share, which
demonstrates solution for such a deployment, that'd be appreciated as
well
Best regards