Only look up resource constants directly available under the Krane module

[camertron]

What are you trying to accomplish with this PR?

I ran into an interesting issue today I thought warranted a PR. I'm using kubedb to launch a Redis instance in my k8s cluster. In addition, I have a constant defined in my project called Redis.

The Redis kubedb resource looks something like this:

kind: Redis
metadata:
  name: foobar
  namespace: foobar-ns
spec:
  ... more stuff here

I tried to deploy using Krane and saw this in the list of discovered resources:

[INFO][2020-06-14 13:52:13 -0700]
[INFO][2020-06-14 13:52:13 -0700]	------------------------------------Phase 1: Initializing deploy------------------------------------
[INFO][2020-06-14 13:52:14 -0700]	All required parameters and files are present
[INFO][2020-06-14 13:52:14 -0700]	Discovering resources:
[INFO][2020-06-14 13:52:17 -0700]	  - <lots of resources>
[INFO][2020-06-14 13:52:17 -0700]	  - redis://127.0.0.1:6379/0
[INFO][2020-06-14 13:52:17 -0700]	  - <lots of resources>

Hmm, that's surprising. What's that Redis URL doing in there? The deploy then failed with this error:

ArgumentError: comparison of Redis with Krane::Secret failed

A little digging revealed this method in kubernetes_resource.rb:

def class_for_kind(kind)
  if Krane.const_defined?(kind)
    Krane.const_get(kind)
  end
rescue NameError
  nil
end

Interestingly, Krane.const_defined?('Redis') returns true. The documentation for const_defined? says it will check for the constant in the module's ancestors (including Object) unless a second false parameter is passed.

How is this accomplished?

Since I assume the intent was to look up constants under the Krane module directly, I added the second false param in this PR. Note that const_get works the same way.

What could go wrong?

Well, I suppose anyone who's relying on the old behavior, either implicitly or explicitly, is could experience a deploy failure. However in my opinion, this is a bug.

[camertron]

Can someone re-run the CLA check for me?

[dturn]

I think you're correct and this behavior is a bug for people using krane as a library. Thanks for the fix!

[timothysmith0609]

Thanks for the fix, that one's pretty sneaky