inline ClientMixin

[grosser]

this always seems like a weird architecture to me, I'd propose to get rid of it and whichever gems used to mix it in can just change to not do that

/cc @cben

[cben]

Yep, good idea.
The original motivation was for openshift_client gem, which is long unnecessary and unmaintained (abonas/openshift_client#31).

[cben]

Searched github for mentions of ClientMixin (not because I have concerns in this case, I just enjoy this aspect of open source that I can get a good sample of depenent code).
Most are simply vendored copies of kubeclient.

• https://github.com/pokka/samson-gitlab/blob/f8db95c35d6b625516011a760d026feb5ae92c2b/plugins/kubernetes/config/initializers/watchers.rb monkey-patches some ancient kubeclient version — before discovery was a thing. If they update to a recent version this file becomes unnecessary.

• https://github.com/taejune/3scale-porta/blob/732944bcd525191a61a9607a4b572fbc67debe1f/test/test_helpers/service_discovery.rb#L19 calls ClientMixin.resource_class, dropped in 3.0.

• https://github.com/zanloy/bms/blob/2c6238c01636f4d0d7174ce65a1c7579a34d5177/connectors/kubectl.rb is a new class that includes ClientMixin. Could simply include Client instead.

• https://github.com/zanloy/bms/blob/2c6238c01636f4d0d7174ce65a1c7579a34d5177/connectors/kubectl.rb adds several new methods (superset of Add ability to patch status of an object #422). Could patch Client instead?

• https://github.com/zendesk/samson/blob/d3a1de89e79e062681685154b74b5f0e76628755/plugins/kubernetes/app/models/kubernetes/resource.rb#L233 calls ClientMixin.underscore_entity. @grosser that's your code :-)
  Can you call it through Client today? Hmm, that doesn't work. Apparently ruby include does not inherit class methods. 😞

  BTW, underscore_entity is not public, and isn't reliable for predicting generated method names (pluralization, resolve_unconventional_method_names...) What's missing from kubeclient to achieve what you do there? probably Expose {create,delete,...}_entity methods to manipulate objects of dynamic kind #332?