feat: migrate manifests from Ingress to Gateway API (HTTPRoute) for Envoy Gateway support

[TineoC]

Description

The sandbox cluster is migrating away from ingress-nginx as it reaches EOL at the end of March 2026. This migration is being handled by adopting Envoy Gateway and the Gateway API.

This repository (balancer-main) provides the base manifests consumed by the cluster. To support this migration, the current Ingress resources should be replaced with HTTPRoute resources.

This migration is tracked in CodeForPhilly/cfp-sandbox-cluster#130.

Proposed Changes

• Replace deploy/manifests/balancer/base/ingress.yaml with an equivalent httproute.yaml.
• The HTTPRoute should define the routing logic (e.g., targeting the balancer service on port 80).
• For the sandbox environment, the HTTPRoute will need to be attached to the main-gateway in the envoy-gateway-system namespace.
  • Note: In cfp-sandbox-cluster, we've already prepared the balancer/kustomization.yaml to consume this new file (see CodeForPhilly/cfp-sandbox-cluster#132).

References

• Cluster Issue: [Architecture] Migrate ingress-nginx to supported alternative (EOL March 2026) cfp-sandbox-cluster#130
• Cluster PR (Infra): infra: configure envoy gateway with cert-manager support cfp-sandbox-cluster#131
• Cluster PR (Balancer Migration): feat: migrate balancer to envoy gateway cfp-sandbox-cluster#132