Istio dropping headers


Hello everyone,

In one of our istio cluster a header “x-app-api_sessionid” is getting dropped, it is visible in logs of our qa cluster for same call without istio installed on the same codebase.

Istio version: 1.0.6

in our server entrypoint for kubernetes cluster is a “loadbalancer” type kubernetes “service” which is pointing to a nginx pod (with envoy).

This nginx pod is then passing the call to other microservices (with envoy too).

Is there a way to make sure no headers get dropped by istio and also this unpredictability of istio makes us think if we change something in our code or add one extra header, we could face issues in future if we go with istio in production.