[openstack-dev] [cliff][osc][barbican][oslo][sdk][all] avoiding option name conflicts with cliff and OSC plugins

Michael Johnson johnsomor at gmail.com
Fri Jan 26 22:10:52 UTC 2018

Should be no issues with python-octaviaclient, we do not use the short options.


On Fri, Jan 26, 2018 at 1:03 PM, Doug Hellmann <doug at doughellmann.com> wrote:
> Excerpts from Doug Hellmann's message of 2018-01-18 10:15:16 -0500:
>> We've been working this week to resolve an issue between cliff and
>> barbicanclient due to a collision in the option namespace [0].
>> Barbicanclient was using the -s option, and then cliff's lister
>> command base class added that option as an alias for sort-columns.
>> The first attempt at resolving the conflict was to set the conflict
>> handler in argparse to 'resolve' [1]. Several reviewers pointed out
>> that this would have the unwanted side-effect of making some OSC
>> commands support the -s as an alias for --sort-columns while the
>> barbicanclient commands would use it for a different purpose.
>> For now we have removed the -s alias from within cliff. However,
>> we want to avoid this problem coming up in the future so we want a
>> better solution.
>> The OSC project has a policy that its command plugins do not use
>> short options (single letter). There are relatively few of them,
>> and it's easy to introduce collisions.  Therefore, they are seen
>> as reserved for more common "global" options such as provided by
>> the base classes in OSC and cliff.
>> I propose that for Rocky we update cliff to change the way options
>> are registered so that conflicting options added by command subclasses
>> are ignored. This would effectively let cliff "own" the short option
>> namespace, and require command classes to use long option names.
>> The implementation details need to be worked out a bit, but I think
>> we can do that by subclassing ArgumentParser and adding a new
>> conflict handler method similar to the existing _handle_conflict_error()
>> and _handle_conflict_resolve().
>> This is going to introduce backwards-incompatible changes in the
>> commands derived from cliff, so before we take any action I wanted
>> to solicit input in the plan.
>> Please let me know what you think,
>> Doug
>> [0] https://bugs.launchpad.net/python-barbicanclient/+bug/1743578
>> [1] https://docs.python.org/3.5/library/argparse.html#conflict-handler
> I have a patch up to implement this in https://review.openstack.org/538335
> Doug
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