Validate networking annotations on RevisionTemplateSpec

[linkvt]

Fixes #13053

Proposed Changes

• Add validation in RevisionTemplateSpec.Validate() to reject unknown networking.knative.dev/* annotations early at Service creation time
• Reuse existing networking.ValidateAnnotations() from the networking package for consistency with SKS validation
• Add test cases for invalid and valid networking annotations on RevisionTemplate

Background

When users mistakenly place networking.knative.dev/visibility: cluster-local as an annotation on spec.template.metadata.annotations (instead of as a label on the Service's metadata.labels), the annotation propagates through Revision → PodAutoscaler → ServerlessService, where SKS validation rejects it. This caused services to silently get stuck in "Unknown" state with no clear error message.

With this fix, users now get an immediate validation error:

validation failed: invalid key name "networking.knative.dev/visibility": spec.template.metadata.annotations

Example of broken resource (click to expand)

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: my-service
spec:
  template:
    metadata:
      annotations:
        # WRONG: This causes the service to get stuck!
        # visibility should be a LABEL on the Service metadata, not here
        networking.knative.dev/visibility: cluster-local
    spec:
      containers:
        - image: gcr.io/knative-samples/helloworld-go

Correct usage:

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: my-service
  labels:
    networking.knative.dev/visibility: cluster-local  # Correct!
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-samples/helloworld-go

Release Note

Services with invalid networking.knative.dev/* annotations on the revision template now fail immediately with a clear error instead of getting stuck.

[knative-prow]

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 80.10%. Comparing base (5fbd94e) to head (8bf896f).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main   #16296   +/-   ##
=======================================
  Coverage   80.10%   80.10%           
=======================================
  Files         215      215           
  Lines       13332    13333    +1     
=======================================
+ Hits        10679    10680    +1     
  Misses       2294     2294           
  Partials      359      359           

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[linkvt]

/retest

[skonto]

Hi @linkvt! Some thoughts:

• Should we keep https://github.com/knative/networking/blob/main/pkg/apis/networking/v1alpha1/serverlessservice_validation.go#L29?
• Do we need to fail earlier like at the Service validation call?
• Are there other annotations that could cause similar issues beyond the networking ones?

[linkvt]

Hi @skonto , thanks for the review!

1. I would say we could keep the validation there as
   • we ensure the SKS is always created with valid annotations and avoid bad annotations e.g. even when it is created by other resources - even if unlikely
   • it doesn't do any damage keeping it
   • the LSP of my IDE didn't show me references in the vendor/ directory so I actually didn't see it when looking for references until now 😅
2. We're actually validating this within the Service validation call, here is the call chain:
   1. Service Validation:

      serving/pkg/apis/serving/v1/service_validation.go

      Line 27 in 4e32e7c

      func (s *Service) Validate(ctx context.Context) (errs *apis.FieldError) {

   2. Call of Service Spec validation:

      serving/pkg/apis/serving/v1/service_validation.go

      Line 38 in 4e32e7c

      errs = errs.Also(s.Spec.Validate(apis.WithinSpec(ctx)).ViaField("spec"))

   3. Call of Configuration Spec validation:

      serving/pkg/apis/serving/v1/service_validation.go

      Line 56 in 4e32e7c

      return ss.ConfigurationSpec.Validate(ctx).Also(

   4. Call of Revision Template validation:

      serving/pkg/apis/serving/v1/configuration_validation.go

      Line 59 in 4e32e7c

      return cs.Template.Validate(ctx).ViaField("template")

   5. Revision Template validation:

      serving/pkg/apis/serving/v1/revision_validation.go

      Line 65 in 4e32e7c

      func (rts *RevisionTemplateSpec) Validate(ctx context.Context) *apis.FieldError {

3. I'm not aware of other annotations but I'm kinda new to the project. Considering that the issue is 3 years old with no recent updates and no upvotes I think it's OK to fix only the problem described here and focus on other bugs afterwards 🙂

Let me know what you think, thanks!