Add TopologySpreadConstraints to Pod kube_types

[sheidkamp]

Description

We support setting nodeSelector, affinity, antiAffinity, and tolerations on the gateways via Gateway Parameters.

This PR adds support for topologySpreadConstraints as well.

Fixes: #11917

Change Type

/kind new_feature

Changelog

Adds `topologySpreadConstraints` to the Pod struct used in GatewayParameters in order to set the corresponding [topologySpreadConstrains](https://kubernetes.io/docs/concepts/scheduling-eviction/topology-spread-constraints/#topologyspreadconstraints-field) field in the gateway-proxy pod.

Notes

To set the topology constraints on a gateway pod, for example as:

  topologySpreadConstraints:
  - maxSkew: 25
    topologyKey: myTopologyKey
    whenUnsatisfiable: ScheduleAnyway

The following resources could be applied:

k apply -f - <<EOF
kind: GatewayParameters
apiVersion: gateway.kgateway.dev/v1alpha1
metadata:
  name: gloo-test
spec:
  kube:
    podTemplate:
      topologySpreadConstraints:
        - maxSkew: 25
          topologyKey: myTopologyKey
          whenUnsatisfiable: ScheduleAnyway

---
kind: GatewayClass
apiVersion: gateway.networking.k8s.io/v1
metadata:
  name: gloo-test
spec:
  controllerName: kgateway.dev/kgateway
  parametersRef:
    group: gateway.kgateway.dev
    kind: GatewayParameters
    name: gloo-test
    namespace: default
---
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: transformation-test-gateway
spec:
  gatewayClassName: gloo-test
  listeners:
    - name: http
      port: 8080
      protocol: HTTP
      allowedRoutes:
        namespaces:
          from: All
---
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: transformation-test-route
spec:
  parentRefs:
    - name: transformation-test-gateway
  hostnames:
    - "www.example.com"
  rules:
    - matches:
        - path:
            type: PathPrefix
            value: /
      backendRefs:
        - name: httpbin
          port: 8000
EOF

[Copilot]

Pull Request Overview

This PR adds support for TopologySpreadConstraints to Pod specifications in the kgateway system. TopologySpreadConstraints allow users to control how pods are distributed across topology domains (like zones or nodes) for better availability and performance.

• Adds TopologySpreadConstraints field to Pod kube_types
• Implements merge logic for combining TopologySpreadConstraints from different sources
• Updates Helm templates and deployer logic to support the new field

Reviewed Changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
api/v1alpha1/kube_types.go	Adds TopologySpreadConstraints field and getter method to Pod struct
pkg/deployer/values.go	Adds TopologySpreadConstraints field to HelmGateway struct
pkg/deployer/merge.go	Implements merge logic for TopologySpreadConstraints
pkg/deployer/deployer_test.go	Adds test coverage for TopologySpreadConstraints
internal/kgateway/helm/kgateway/templates/gateway/proxy-deployment.yaml	Updates Helm template to render TopologySpreadConstraints
internal/kgateway/deployer/gateway_parameters.go	Wires TopologySpreadConstraints from pod config to gateway values
install/helm/kgateway-crds/templates/gateway.kgateway.dev_gatewayparameters.yaml	Adds CRD schema for TopologySpreadConstraints
api/v1alpha1/zz_generated.deepcopy.go	Generated deepcopy implementation for TopologySpreadConstraints
api/applyconfiguration/internal/internal.go	Updates schema YAML for apply configurations
api/applyconfiguration/api/v1alpha1/pod.go	Adds apply configuration support for TopologySpreadConstraints

Comments suppressed due to low confidence (1)

[timflannagan]

@sheidkamp Looks like there's merge conflicts. I'd also use Fixes #11917 in the PR description to auto-close the issue, but we can also manually link it up.