feat(appset-clusters-excludeSelector): Add option to ApplicationSet generators to exclude clusters

[Carles-Figuerola]

Enhancement proposal: #25069

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[codecov]

Codecov Report

❌ Patch coverage is 38.46154% with 8 lines in your changes missing coverage. Please review.
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Files with missing lines	Patch %	Lines
applicationset/generators/cluster.go	38.46%	7 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master   #25070   +/-   ##
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  Coverage          ?   62.23%           
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  Files             ?      351           
  Lines             ?    49223           
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  Misses            ?    15653           
  Partials          ?     2937           

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[blakepettersson]

Slack thread

...could you not use post-selectors to do the negative filtering after collecting all of the ones you do want?
Something like

spec:
  generators:
    - clusters:
        selector:
          matchExpressions:
            - key: labelA
              operator: Exists
            - key: labelI
              operator: Exists
            - key: labelX
              operator: Exists
      selector:
        matchExpressions:
          - key: labelA
            operator: NotIn
            values:
              - "c"
          - key: labelI
            operator: NotIn
            values:
              - "j"
          - key: labelX
            operator: NotIn
            values:
              - "y"

[Carles-Figuerola]

The post-selector seems to operate with a different set of labels than the cluster generator. I have been able to use the post-selector to filter based on name, server, etc, but not on any of the cluster secret labels.

[blakepettersson]

The post-selector seems to operate with a different set of labels than the cluster generator. I have been able to use the post-selector to filter based on name, server, etc, but not on any of the cluster secret labels

Yeah you're right, I missed that part 🙈

I wonder if we couldn't extend the cluster generator to set the labels in a more intuitive way, so that post-selectors could make use of the same selector logic?