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On Wed, Nov 13, 2013 at 2:19 PM, Oleg Gelbukh <ogelbukh at mirantis.com> wrote:

> Doug,
>
>
> On Wed, Nov 13, 2013 at 9:49 PM, Doug Hellmann <
> doug.hellmann at dreamhost.com> wrote:
>
>>
>>
>>
>> On Mon, Nov 11, 2013 at 6:08 PM, Mark McLoughlin <markmc at redhat.com>wrote:
>>
>>>
>>> One thing worth trying would be to encode the validation rules in the
>>> config option declaration.
>>>
>>> Some rules could be straightforward, like:
>>>
>>> opts = [
>>>   StrOpt('foo_url',
>>>          validate_rule=cfg.MatchesRegexp('(git|http)://')),
>>> ]
>>>
>>> but the rule you describe is more complex e.g.
>>>
>>> def validate_proxy_url(conf, group, key, value):
>>>     if not conf.vnc_enabled:
>>>         return
>>>     if conf.ssl_only and value.startswith("http://"):
>>>         raise ValueError('ssl_only option detected, but ...')
>>>
>>> opts = [
>>>   StrOpt('novncproxy_base_url',
>>>          validate_rule=validate_proxy_url),
>>>   ...
>>> ]
>>>
>>> I'm not sure I love this yet, but it's worth experimenting with.
>>>
>>
>> One thing to keep in mind with the move to calling register_opt() at
>> runtime instead of import time is the service may run for a little while
>> before it reaches the point in the code where the option validation code is
>> triggered. So I like the idea, but we may want a shortcut for validation.
>>
>> We could add a small app to oslo.config that will load the options in the
>> same way the conf generator and doc tool will, but then also read the
>> configuration file and perform the validation.
>>
>
> We implement similar approach in Rubick [1]. Collector script generates
> configuration schema from code [2], while generator script [3] allows to
> have different versions of configuration schema:
>
> [1] https://github.com/MirantisLabs/rubick/tree/master/rubick/schemas
> [2]
> https://github.com/MirantisLabs/rubick/blob/master/rubick/schemas/collector.py#L189
> [3]
> https://github.com/MirantisLabs/rubick/blob/master/rubick/schemas/generator.py
>
> I think it would be useful to discuss pros and cons of contributing parts
> of this code to oslo.config.
>

There's definitely some overlap with the planned work from
https://etherpad.openstack.org/p/icehouse-oslo-config-import-side-effectsand
the existing sample file generator, so it would be good to coordinate.

Doug


>
> --
> Best regards,
> Oleg Gelbukh
> Mirantis Labs
>
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>
>
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