the injection pattern for extending charms

[Gary Poster]

On 08/24/2013 12:30 PM, Patrick Hetu wrote:
> Hi guys,

Hi Patrick.  Sorry for the slow reply.

> I was looking for a way to extends the buildbot-master charm
> to be able to add configuration chunks from an other charm or
> a subordinate. For configuring the new OpenStack latent buildslave for
> example:
> 
> http://docs.buildbot.net/current/manual/cfg-buildslaves.html?highlight=latent#openstack
> 
> The way I was going to propose was to add a buildbot-settings provider
> to metadata.yaml file.

This would be a link to a git repo or similar?  If so, I like it.

> Charms will then use it to send configuration that would be injected a
> "juju_settings" directory
> in the buildbot install directory.
> 
> I would then add this python code at the end of the master.cfg file:
> 
> 
> import imp
> import glob
> from os.path import abspath, dirname, join
> 
> PROJECT_DIR = abspath(dirname(__file__))
> 
> conffiles = glob.glob(join(PROJECT_DIR, 'juju_settings', '*.py'))
> 
> for f in conffiles:
>     execfile(abspath(f))
> 
> 
> 
> The code sent by charms or subordinates would be in this form:
> 
> c['buildbotURL'] = "http://my_new_url_here"
> c['builders'] += your_builder_code_here
> c['schedulers'] += your_schedulers_code_here
> etc
> 
> 
> This is the pattern I used in the python-django charm to extend the
> settings. So before
> spreading the pattern, I would like to have your opinion.

FWIW, my team developed the buildbot charms early last year.  We have
not maintained it for a long time, and it would be great for the charms
to have a maintainer, hint hint hint...

Gary

> 
> Cheers,
> 
> Patrick
> 
>