enable case-insensitivity in kind field

[liftedkilt]

This addresses one of the concerns presented in #4

Referencing https://github.com/kubernetes/community/blob/master/contributors/devel/api-conventions.md#naming-conventions, it appears safe to assume that all values of type "Kind" will have an initial uppercase character.

[hausdorff]

Wow, thanks for the PR!

This is a super good idea, and we should definitely do it, but I think client-go exposes its kind aliasing, which would allow us to write po instead of Pod, deploy instead of Deployment, svc instead of Service, and so on. Let me see if I can dig it up, and if I can, then we might consider going that route....

[liftedkilt]

Thanks for the tip - I'll poke at client-go in a little bit and see what I can find.

[hausdorff]

Hmm, let's just merge this since it's a clear improvment, and my suggestion looks like it will not be trivial. To do this "the right way (TM)" I believe we have to:

1. Get the OpenAPI spec from the API server.
2. Parse out the apiextensions and apiversions
3. Loop through all the kinds, assembling a big map of alias -> kind, provided by the specification
4. Finally, take the argument the user has given us, and look it up in the alias dictionary.

In the mean time I personally rather just hard-code the aliases for the core kinds and wait for someone to complain about the lack of aliases for CRDs. :)

[liftedkilt]

in client-go/discovery/restmapper.go, there are two helper functions:

// KindFor takes a partial resource and returns back the single match.
// It returns an error if there are multiple matches.
func (d *DeferredDiscoveryRESTMapper) KindFor(resource schema.GroupVersionResource) (gvk schema.GroupVersionKind, err error) {
	del, err := d.getDelegate()
	if err != nil {
		return schema.GroupVersionKind{}, err
	}
	gvk, err = del.KindFor(resource)
	if err != nil && !d.cl.Fresh() {
		d.Reset()
		gvk, err = d.KindFor(resource)
	}
	return
}

// KindsFor takes a partial resource and returns back the list of
// potential kinds in priority order.
func (d *DeferredDiscoveryRESTMapper) KindsFor(resource schema.GroupVersionResource) (gvks []schema.GroupVersionKind, err error) {
	del, err := d.getDelegate()
	if err != nil {
		return nil, err
	}
	gvks, err = del.KindsFor(resource)
	if len(gvks) == 0 && !d.cl.Fresh() {
		d.Reset()
		gvks, err = d.KindsFor(resource)
	}
	return
}

That makes it look like you can pass a partial kind to those functions, it will query a running instance of API server to get the mappings of kinds to shortnames, and then it will validate it? At least that was as best as I could get a handle on what was going on...kubernetes internal code is such a giant ball of spaghetti - interfaces everywhere!