Real Client IP Behind Istio Ambient Gateway: Secure X-Forwarded-For in Go

Istio ambient mesh is great for many things ie. sidecar-free mTLS, L4 authorization with ztunnel, a clean Gateway API entry point, and a much smaller per-pod footprint than the old sidecar model. But the moment you put a service behind an ambient ingress gateway, one thing quietly breaks: access logs stop showing who is actually calling the service. And the way it breaks is nastier than the usual “read X-Forwarded-For” story, because it breaks intermittently.