Reduce operator memory usage by using an informer with limited scope

[blkperl]

Summary

In #2545, @zachaller suggested the following could be used to lower memory usage.

kubeInformerFactory := kubeinformers.NewSharedInformerFactoryWithOptions(
				kubeClient,
				resyncDuration,
				kubeinformers.WithNamespace(namespace), kubeinformers.WithTweakListOptions(func(options *metav1.ListOptions) {
					options.LabelSelector = "rollouts-managed=managed-key"
				}))

The key being WithTweakListOptions, and we would also probably need to add some managed by label to the rs. We might even be able to just use a LabelSelector="rollouts-pod-template-hash" meaning just to have the key and match any value

This has been done in other operators using the NewCache pattern:

• https://github.com/tigera/operator/blob/master/main.go#L231-L235
• https://github.com/argoproj-labs/argocd-operator/blob/master/main.go#L123

The following links have documentation on how use the cache selectors.

• https://master.sdk.operatorframework.io/docs/best-practices/designing-lean-operators/
• https://github.com/kubernetes-sigs/controller-runtime/blob/master/designs/use-selectors-at-cache.md

Use Cases

This would reduce memory usage on clusters with large amounts of replicasets.

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This issue is stale because it has been open 60 days with no activity.

[github-actions]

This issue is stale because it has been open 60 days with no activity.