You may need to set some specifications to forward custom headers, if you are using stock ingress controller for your cluster.

apiVersion: v1
kind: ConfigMap
metadata:
  name: ingress-nginx-controller
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: "ingress-nginx"
    app.kubernetes.io/instance: "ingress-nginx"
    app.kubernetes.io/component: "controller"
    app.kubernetes.io/part-of: "ingress-nginx"
    app.kubernetes.io/version: "1.12.3"
data:
  use-forwarded-headers: "true"
  proxy-real-ip-cidr: "10.0.0.0/8" # Replace with your trusted CIDR
  compute-full-forwarded-for: "true"
  enable-real-ip: "true"
  allow-snippet-annotations: "true"

use-forwarded-headers

If true, NGINX passes the incoming X-Forwarded-* headers to upstreams. Use this option when NGINX is behind another L7 proxy / load balancer that is setting these headers.