Open Stack

On Tue, Oct 15, 2013 at 2:31 AM, Zane Bitter <zbitter at redhat.com> wrote:
> On 15/10/13 02:18, Sam Alba wrote:
>>
>> Hello,
>>
>> I am working on a Heat plugin that makes a new resource available in a
>> template. It's working great and I will opensource it this week if I
>> can get the packaging right...
>
>
> Awesome! :)
>
>
>> Right now, I am linking my module.py file in /usr/lib/heat to get it
>> loaded when heat-engine starts. But according to the doc, I am
>> supposed to be able to make the plugin discoverable by heat-engine if
>> the module appears in the package "heat.engine.plugins"[1]
>
>
> I think the documentation may be leading you astray here; it's the other way
> around: once the plugin is discovered by the engine, it will appear in the
> package heat.engine.plugins. So you should be able to do:
>
>>>> import heat.engine.resources
>>>> heat.engine.resources.initialise()
>>>> from heat.engine.plugins import module
>>>> print module.resource_mapping()
>
> (FWIW this is working for me on latest master of Heat.)
>
> As far as making the plugin discoverable is concerned, all you should have
> to do is install the module in /usr/lib/heat/.
>
>
>> I looked into the plugin_loader module in the Heat source code and it
>> looks like it should work. However I was unable to get a proper Python
>> package.
>>
>> Has anyone been able to make this packaging right for an external Heat
>> plugin?
>
>
> I've never tried to do this with a Python package, the mechanism is really
> designed more for either dropping the module in there manually, or
> installing it from a Debian or RPM package.
>
> It sounds like what you're doing is trying to install the package in
> /usr/lib/python2.7/site-packages/ (or in a venv) in the package
> heat.engine.plugins and get the engine to recognise it that way? I don't
> think there's a safe way to make that work, because the plugin loader
> creates its own heat.engine.plugins package that will replace anything that
> exists on that path (see line 41 of plugin_loader.py).
>
> Heat (in fact, all of OpenStack) is designed as a system service, so the
> normal rules of Python _application_ packaging don't quite fit. e.g. If you
> want to use a plugin locally (for a single user) rather than install it
> globally, the way to do it is to specify a local plugin directory when
> running heat-engine, rather than have the plugin installed in a venv.
>
> Hope that helps.

Thanks Zane, it helps.


-- 
@sam_alba