bump k8s dependencies

[varshaprasad96]

This commit bumps:

1. k8s dependencies to 1.21+
2. Controller runtime to 0.9.2
3. Kubebuilder to the latest version at the time of this commit

This is to make the plugin compatible with the recent bump of dependencies in Operator SDK.

[fabianvf]

/lgtm

[coveralls]

Pull Request Test Coverage Report for Build 1117514105

• 12 of 12 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.04%) to 89.693%

---

Totals
Change from base Build 1102982089:	-0.04%
Covered Lines:	1375
Relevant Lines:	1533

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💛 - Coveralls

[fabianvf]

/lgtm

/cc @joelanford the apidiff breakage is due to the c-r bump, do we need to find a way to maintain that or are we good dropping it?

[joelanford]

To make this re-usable and to de-clutter this file, what do you think about keeping pkg/manager/delegatingclient.go around and defining a function there that returns a function with the NewClientFunc signature.

It may even be possible (though maybe not necessary) to keep the existing code around (maybe deprecate it) and have this new function just wrap the existing code.

Something like:

func NewCachingClientFunc() cluster.NewClientFunc {
	return func(cache cache.Cache, config *rest.Config, options client.Options, uncachedObjects ...client.Object) (client.Client, error) {
		return NewCachingClientBuilder().WithUncached(uncachedObjects...).Build(cache, config, options)
	}
}

This approach would let you keep the tests for this around in an easier-to-maintain way as well.

[varshaprasad96]

@joelanford the previous implementation returned manager.ClientBuilder which has been removed from controller-runtime, so we can't keep the existing code.

On creating a wrapper after removing existing code, do you mean having this ?

func NewCachingClientFunc() cluster.NewClientFunc {
	return func(cache cache.Cache, config *rest.Config, options client.Options, uncachedObjects ...client.Object) (client.Client, error) {
		c, err := client.New(config, options)
		if err != nil {
			return nil, err
		}

		return client.NewDelegatingClient(client.NewDelegatingClientInput{
			CacheReader:       cache,
			Client:            c,
			UncachedObjects:   uncachedObjects,
			CacheUnstructured: true,
		})
	}
}

[joelanford]

/lgtm