docs: add the default resource exclusions

[jenting]

Add the full resource exclusion lists.

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[codecov]

Codecov Report

Patch and project coverage have no change.

Comparison is base (3cb7eca) 49.56% compared to head (f2135ab) 49.57%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #13897   +/-   ##
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  Coverage   49.56%   49.57%           
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  Files         256      256           
  Lines       43920    43920           
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+ Hits        21770    21773    +3     
+ Misses      19987    19985    -2     
+ Partials     2163     2162    -1     

see 2 files with indirect coverage changes

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[morey-tech]

I don't see ""/Endpoints in the list of core exclusions, should it be ""/Event instead?

argo-cd/util/settings/resources_filter.go

Line 7 in 8840929

var coreExcludedResources = []FilteredResource{

Suggested change

	Resources can be excluded from discovery and sync so that Argo CD is unaware of them. For example, the apiGroup/kind `events.k8s.io/*`, `metrics.k8s.io/*`, `coordination.k8s.io/Lease`, and `""/Endpoints` are always excluded. Use cases:
	Resources can be excluded from discovery and sync so that Argo CD is unaware of them. For example, the apiGroup/kind `events.k8s.io/*`, `metrics.k8s.io/*`, `coordination.k8s.io/Lease`, and `""/Event` are always excluded. Use cases:

[jenting]

@morey-tech
Thank you for reviewing the PR.
Here is the code reference

• https://github.com/argoproj/gitops-engine/blob/c0ffe8428a23011ae9f6d0d3d01f9bf6200a4339/pkg/cache/cluster.go#L1076-L1078
• https://github.com/argoproj/gitops-engine/blob/c0ffe8428a23011ae9f6d0d3d01f9bf6200a4339/pkg/cache/cluster.go#L1050-L1054

[morey-tech]

It seems like Endpoints resource isn't excluded using the resource filter mechanism but rather a separate one in the gitops engine. Not sure it makes sense to include it in the example of what is always excluded using the resource filter.

[jenting]

The Endpoints resource is filtered when the resource update event comes in. Ref to code.

The events.k8s.io/*, metrics.k8s.io/*, coordination.k8s.io/Lease resources are filtered when comparing the live state versus git manifest. Ref to code.

[morey-tech]

Since this section of the docs is for the Resource Exclusion feature and not generally about filtered resources, I'm hesitant to include Endpoints in the list, even though they are also excluded (but in a different context). Ultimately, it's okay since the user will know they are excluded and can't change that.

[todaywasawesome]

Because the purpose of this reference is just to give an example, it doesn't need to be a compressive list. But I would leave it as is because these resources are excluded by default.

[jenting]

Because we are working on tuning the app controller CPU high issue.
It'd be good to doc existing excluded resources rather than trace the source code.

[todaywasawesome]

Because the purpose of this reference is just to give an example, it doesn't need to be a compressive list. But I would leave it as is because these resources are excluded by default.

[pasha-codefresh]

LGTM, thank you