Update ObservabilityPolicy API to have minimum one target ref

[salonichf5]

Proposed changes

Write a clear and concise description that helps reviewers understand the purpose and impact of your changes. Use the
following format:

Problem: User wants ObservabilityPolicy CRD should require a minimum of 1 TargetRef.

Solution: Add validation to have minimum one target ref for the ObservabilityPolicy CRDs.

Testing:

Tested manually using the example. Installed observabilityPolicy with on branch main, a target ref and ensuring everything works as expected.

Tested with specifying no target refs

kubectl apply -f - <<EOF
apiVersion: gateway.nginx.org/v1alpha1
kind: ObservabilityPolicy
metadata:
  name: coffee
spec:
  targetRefs: []
  tracing:
    strategy: ratio
    ratio: 75
    spanAttributes:
    - key: coffee-key
      value: coffee-value
EOF
The ObservabilityPolicy "coffee" is invalid:
* spec.targetRefs: Invalid value: 0: spec.targetRefs in body should have at least 1 items
* spec.targetRefs: Invalid value: "array": TargetRef Kind must be: HTTPRoute or GRPCRoute

Please focus on (optional): If you any specific areas where you would like reviewers to focus their attention or provide
specific feedback, add them here.

Closes #2524

Checklist

Before creating a PR, run through this checklist and mark each as complete.

• I have read the CONTRIBUTING doc
• I have added tests that prove my fix is effective or that my feature works
• I have checked that all unit tests pass after adding my changes
• I have updated necessary documentation
• I have rebased my branch onto main
• I will ensure my PR is targeting the main branch and pulling from my branch from my own fork

Release notes

If this PR introduces a change that affects users and needs to be mentioned in the release notes,
please add a brief note that summarizes the change.

ObservabilityPolicy API requires minimum one target ref specified when creating a policy.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.86%. Comparing base (cafbd5c) to head (1ba62a1).
Report is 1 commits behind head on main.

Additional details and impacted files

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  Coverage   89.86%   89.86%           
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  Files         107      107           
  Lines       10997    10997           
  Branches       50       50           
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  Hits         9883     9883           
  Misses       1054     1054           
  Partials       60       60           

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[salonichf5]

Should we mention in the release-note about the deprecation of v1alpha2 .

Currently, the user can use both versions of ObservabilityPolicy but the stored version is v1alpha2 . How do we deprecate it after 3 weeks?

[ADubhlaoich]

Doc update LGTM!

[sjberman]

If you install an old version of the policy, can you still view it properly when running kubectl get or describe? And everything still works as expected? Same with the new version?

Also, please update all ObservabilityPolicy examples to use the new version.

We should mention this in the release notes. After three releases we'll remove the v1alpha1 version, so let's create an issue targeted for the 2.3 milestone for this.

[salonichf5]

Created a new issue to remove version v1alpha1

[salonichf5]

If you install an old version of the policy, can you still view it properly when running kubectl get or describe? And everything still works as expected? Same with the new version?

Also, please update all ObservabilityPolicy examples to use the new version.

We should mention this in the release notes. After three releases we'll remove the v1alpha1 version, so let's create an issue targeted for the 2.3 milestone for this.

Yes, when I create a policy with CRDs on main, the policy is set to v1alpha1 version. When I apply the newly defined CRDs on my branch, the policy gets updated to v1alpha2

We can still create a policy with version v1alpha1 but it automatically gets upgraded to v1alpha2 since that is the stored version.

[sjberman]

Let's update the release note to include what the actual change is (relating to the targetRef minimum)