Namespaces included by labelSelector act as IncludedNamespaces for Backup

[kaovilai]

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Please add a summary of your change

Namespaces included by backup's selector behave the same as specifying backup.IncludedNamespaces. All resources under the labeled namespace is included.

Prior to this change, labeled namespaces are included, but anything else under the namespace if not labeled are not.

Does your change fix a particular issue?

Fixes #7492

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• Created a changelog file (make new-changelog) or comment /kind changelog-not-required on this PR.
• Updated the corresponding documentation in site/content/docs/main.

[codecov]

Codecov Report

Attention: Patch coverage is 92.30769% with 3 lines in your changes missing coverage. Please review.

Project coverage is 58.99%. Comparing base (ebbeb7a) to head (7f5c57e).

Files with missing lines	Patch %	Lines
pkg/backup/item_collector.go	92.30%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8342      +/-   ##
==========================================
- Coverage   58.99%   58.99%   -0.01%     
==========================================
  Files         367      367              
  Lines       38847    38870      +23     
==========================================
+ Hits        22918    22931      +13     
- Misses      14467    14475       +8     
- Partials     1462     1464       +2     

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[blackpiglet]

I understand there is a requirement from the community to back up resources under the labelled namespace, but we can also do that by using the namespace filter, do we need a new way to do the same function?

[kaovilai]

Some admins may find it easier to automate ns backup by label.
Perhaps individual small teams label their resources.
In some orgs, not everyone will have RBAC to create modify backups.velero.io custom resources.
And backing up by including the label may be a preferred way if available for some.

Apart from velero issue this pr fixes, it has also been requested to our team in https://issues.redhat.com/browse/OADP-4572

I think the question is, when is the current behavior of backing up namespace but not namespaced resources within it desirable?

The previous fix already decided that any namespace not included by namespace filters like label should not be in the backup.

Now we're just saying every namespace included via namespace filters (including label) will have namespaced resources of those namespaces in the backup.

[reasonerjt]

@kaovilai Thanks for this PR, but have we reached agreement in terms of whether we should implement it?
cc @blackpiglet

[kaovilai]

I don't think we have reached agreements yet.

[blackpiglet]

@kaovilai
We can discuss scenarios requiring labels as the namespace filters, but please note this is a break change.

I agree that only backing up the namespace with selected labels without any resources in it is not a common use case, but at least, we have that option.

After introducing this change, we lost that option.

If the introduced method is the preferable option, we can go forward that way, but before applying it, I think we need to make sure that.

[kaovilai]

Another thing with this implementation is that namespaces included via label selector would not show up in backup describe under IncludedNamespaces, but would likely still show in Resource List. I think that should be good enough.