enhance handling prune for CR

[xuzhenglun]

What this PR does / why we need it:

1. allow CR to decide whether to enable pruning resources;
2. allow CR to decide what kinds of resources should be pruned.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

introduce 2 interfaces to let CR can decide whether and how to prune resources. When none of them are implemented, the behavior should be the same as before. So I think this is not a breaking change.

Additional documentation:

[k8s-ci-robot]

Hi @xuzhenglun. Thanks for your PR.

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[xuzhenglun]

ping @atoato88

This PR enhances the ability of prune, and it doesn't relate with DirectApplier. I would be very grateful if you could take a look at this PR.

[atoato88]

I agree with this PR's enhancement about prune-whitelist.

I think kubebuilder-declarative-pattern has similar functions by WithApplyPrune already. I think this framework chosed implement With*** functions for manipurating, so it's prefer to update WithApplyPrune or add new With*** functions if you would like to enhance prune functionality. e.g. implement new WithPruneWhitelist? WDYT?

[xuzhenglun]

agree

With*** function works just fine when we want to build a specific addon operator. However, I'm trying to implement a generic AddonManager for Cluster. My user could choose to enable pruning by setting a flag in CR. Furthermore, consisting of Addon could have CRD inside, so they should be able to configure the white list to determine what kind of resource could be pruned.

To achieve the above by using the WithPrune function, It's necessary to pass CR to the user's function, and it will change the function signature of WithPrune which can be a breaking change. Secondly, framework users still need to implement methods like Prune or PruneWhiteList anyway, because those configurations are defined in CR.

WDYT?

[atoato88]

Thank you to explain the context detailed. I agree with your thinking, I think it's preferable for achieve your requirements.

BTW, I left review comments above, please check those.

[xuzhenglun]

Thank you to explain the context detailed. I agree with your thinking, I think it's preferable for achieve your requirements.

BTW, I left review comments above, please check those.

Thanks for your review. I append some comments in the source code and just updated this PR.

[atoato88]

/approve Thank you to update quickly!

[atoato88]

/approve cancel oh, we should check test before approving.

[atoato88]

/ok-to-test

[atoato88]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: atoato88, xuzhenglun

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/kubernetes-sigs/kubebuilder-declarative-pattern/blob/master/OWNERS)~~ [atoato88] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[xuzhenglun]

@atoato88 still needs an LGTM label to merge. Is something I need to do yet?

[atoato88]

/lgtm