consistent label selector for Service - include app label

[a7i]

Proposed Changes

• components such as controller, autoscaler use the selector label app while webhook and domainmapping-webhook use the role selector. This change includes the app label which brings consistency across all resources.

Note and Service and PodDisruptionBudget selectors are not immutable, meaning that they can change (unlike Deployment/StatefulSet).

Release Note

Add `app` label to Service selector for `webhook` and `domainmapping-webhook`.

[knative-prow]

Welcome @a7i! It looks like this is your first PR to knative/serving 🎉

[knative-prow]

Hi @a7i. Thanks for your PR.

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[psschwei]

Thanks for the PR!
/ok-to-test

@dprotaso any legacy reason why we preferred role over app for some components?

[codecov]

Codecov Report

Base: 86.44% // Head: 86.47% // Increases project coverage by +0.02% 🎉

Coverage data is based on head (a1dbe09) compared to base (76005a0).
Patch has no changes to coverable lines.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13265      +/-   ##
==========================================
+ Coverage   86.44%   86.47%   +0.02%     
==========================================
  Files         196      196              
  Lines       14600    14600              
==========================================
+ Hits        12621    12625       +4     
+ Misses       1678     1675       -3     
+ Partials      301      300       -1     

Impacted Files	Coverage Δ
pkg/autoscaler/statserver/server.go	78.10% <0.00%> (+0.72%)	⬆️
pkg/reconciler/configuration/configuration.go	84.36% <0.00%> (+1.42%)	⬆️

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[skonto]

The app label seems to be a requirement for istio telemetry. Also there is this issue #13168 that discusses avoiding using the label.

[dprotaso]

Also there is this issue #13168 that discusses avoiding using the label.

That's referring to the app label we're automatically adding to the revision pods/deployment.

I think role is just a legacy thing we don't need anymore - it looks like it was part of the initial commit

[dprotaso]

Let's make sure we have app in the selector and in a subsequent release we can drop the role label.

[dprotaso]

bump @a7i - you still interested in landing this PR?

[a7i]

Let's make sure we have app in the selector and in a subsequent release we can drop the role label.

It's going to be tough to remove labels from Deployment selectors as they're immutable. It will require a forced recreate.

[dprotaso]

It will require a forced recreate.

I see - then let's not worry about it then.

/lgtm
/approve

[knative-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: a7i, dprotaso

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