title: Add a custom header per rule on Kubernetes Ingress with Istio
body: <p>I have created a Kubernetes ingress on my cluster where it uses Istio as an ingress controller. I <em>don't</em> want to use the <code>gateway</code> and <code>virtual service</code> provided by Istio and would like to set this up with the good old Kubernetes ingress.</p>
  <p>What I am having a hard time with is configuring a custom header to this ingress. I know with:</p>
  <ul>
  <li>Nginx ingress controller, I can use <code>nginx.ingress.kubernetes.io/configuration-snippet: 'more_set_input_headers &quot;foo: bar&quot;;'</code></li>
  <li>Traefik, I can use <code>ingress.kubernetes.io/custom-request-headers: &quot;foo: bar&quot;</code></li>
  </ul>
  <p>What is the corresponding annotation while using Istio? or is that even possible while using Istio this way?</p>