Add Gateway API (HTTPRoute) support due to ingress-nginx retirement

[gagantrivedi]

Background

Kubernetes ingress-nginx controller is being retired with maintenance ending in March 2026, with no further security updates after that date:
https://www.kubernetes.dev/blog/2025/11/12/ingress-nginx-retirement/

The Kubernetes SIG Network recommends migrating to Gateway API, which is now the preferred way to handle ingress traffic.

Current Limitation

The Flagsmith Helm chart currently only supports standard Kubernetes Ingress resources (networking.k8s.io/v1). There is no support for Gateway API resources (gateway.networking.k8s.io/v1).

Requested Feature

Add support for Kubernetes Gateway API alongside existing Ingress support:

• Support for HTTPRoute resources for frontend, api, and sse endpoints
• Allow users to choose between Ingress (legacy) and Gateway API (modern) via values.yaml
• Maintain backward compatibility with existing Ingress configurations

Example configuration structure:

gateway:
  enabled: false  # New option
  className: null
  frontend:
    enabled: false
    parentRefs: []
    hostnames: []
    rules: []
  api:
    enabled: false
    parentRefs: []
    hostnames: []
    rules: []
  sse:
    enabled: false
    parentRefs: []
    hostnames: []
    rules: []

# Existing ingress config remains for backward compatibility
ingress:
  frontend:
    enabled: false
    # ... existing fields



References

- https://gateway-api.sigs.k8s.io/
- https://www.kubernetes.dev/blog/2025/11/12/ingress-nginx-retirement/
- https://gateway-api.sigs.k8s.io/api-types/httproute/

[germangarces]

Gateway API requires two things beyond the HTTPRoute resources themselves:

1. Gateway API CRDs (kubectl apply -f https://github.com/kubernetes-sigs/gateway-api/releases/latest/download/standard-install.yaml)
2. A Gateway controller (e.g., Envoy Gateway, Istio, Cilium, NGINX Gateway Fabric)

Should the chart handle either of these, or should we assume users install them independently?

☝️ My recommendation is the first option: document the prerequisites and let users bring their own controller. Gateway controller choice is an infrastructure-level decision that varies widely across clusters.