title: Canary (gradual) rollouts of VirtualService changes
body: <p>We have a VirtualService per microservice in our mesh - services A, B, C each have a VirtualService that describe how to route traffic towards them.</p>
  <p>When performing changes to those VirtualServices we'd like them to be applied gradually - apply the new VS definition e.g. to 1% of traffic, then 10%, etc.</p>
  <p>How can we achieve that?</p>
  <p>E.g. we'd like to change the <code>timeout</code> or <code>retries</code> settings under <a href="https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPRoute" rel="nofollow noreferrer">https://istio.io/latest/docs/reference/config/networking/virtual-service/#HTTPRoute</a> and canary-rollout them.</p>