feat(backstage): Add Gateway API HTTPRoute support as Ingress successor

[younsl]

Description of the change

Add HTTPRoute resource template and values configuration for Gateway API as an alternative to traditional Ingress.

Gateway API is the successor to Ingress and is now the recommended approach for HTTP routing in Kubernetes. The Ingress API spec has been frozen and will not receive new features, while Gateway API is actively developed with richer routing capabilities and better role separation.

Changes

• Add templates/httproute.yaml template
• Add httpRoute configuration in values.yaml
• Add ci/httproute-values.yaml for testing
• Add httpRoute schema to values.schema.tmpl.json

Existing or Associated Issue(s)

None

Additional Information

Example usage

httpRoute:
  enabled: true
  parentRefs:
    name: my-gateway
  hostnames:
    - backstage.example.com

This configuration creates an HTTPRoute that attaches to a Gateway named my-gateway and routes traffic for backstage.example.com to the Backstage service.

apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: my-release-backstage
spec:
  parentRefs:
    - group: gateway.networking.k8s.io
      kind: Gateway
      name: my-gateway
  hostnames:
    - "backstage.example.com"
  rules:
    - matches:
        - path:
            type: PathPrefix
            value: /
      backendRefs:
        - group: ""
          kind: Service
          name: my-release-backstage
          port: 7007
          weight: 1

References

• https://gateway-api.sigs.k8s.io/
• https://gateway-api.sigs.k8s.io/references/spec/#gateway.networking.k8s.io/v1.HTTPRoute
• https://kubernetes.io/blog/2021/04/22/evolving-kubernetes-networking-with-the-gateway-api/
• feat(opencost): add Gateway API HTTPRoute support opencost/opencost-helm-chart#322

Checklist

• Chart version bumped in Chart.yaml according to semver.
• Variables are documented in the values.yaml and added to the README.md. The helm-docs utility can be used to generate the necessary content. Use helm-docs --dry-run to preview the content.
• JSON Schema generated.
• List tests pass for Chart using the Chart Testing tool and the ct lint command.

[github-actions]

This PR has been automatically marked as stale because it has not had recent activity from the author. It will be closed if no further activity occurs. If the PR was closed and you want it re-opened, let us know and we'll re-open the PR so that you can continue the contribution!

[younsl]

Gentle ping @vinzscam

[younsl]

Not stale

[vinzscam]

Thank you! I've added a bunch of comments regarding parentRefs which at the moment is hardcoded to a single value. Have a look!

[younsl]

Thanks for the detailed review! I agree parentRefs should support multiple values. I'll update it to accept a list so users can attach the route to multiple Gateways. Will push the changes shortly.

[younsl]

Note

Heads up for reviewers: CI chart testing is expected to fail on this PR because HTTPRoute is a Gateway API resource that requires the Gateway API CRDs to be installed in the cluster, which the CI environment does not have.

# Install Gateway API CRDs
kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/download/v1.2.1/standard-install.yaml

[younsl]

@vinzscam PTAL