mirroring sample removed? is there anything wrong in mirroring sample?

[motocoder-cn]

i read docs in :https://iter8.tools/0.6/tutorials/traffic-engineering/mirroring/

but i do not understand how follow virtualservice can mirror request ?

this virtualservice request & mirror request with:
same host: knative-local-gateway.istio-system.svc.cluster.local
same authority: example.com

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: example-mirroring
spec:
  gateways:
  - mesh
  - knative-serving/knative-ingress-gateway
  hosts:
  - example.com
  http:
  - rewrite:
      authority: example.com
    route:
    - destination:
        host: knative-local-gateway.istio-system.svc.cluster.local
    mirror:
      host: knative-local-gateway.istio-system.svc.cluster.local
    mirrorPercent: 40

prefix: example.com-shadow will never match
can sample-app-v2.default.svc.cluster.local be called?

i found mirroring sample has been removed, is this wrong?

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: example-routing
spec:
  gateways:
  - knative-serving/knative-local-gateway
  hosts:
  - "*"
  http:
  - match:
    - authority:
        prefix: example.com-shadow
    route:
    - destination:
        host: sample-app-v2.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: sample-app-v2
  - match:
    - authority:
        prefix: example.com
    route:
    - destination:
        host: sample-app-v1.default.svc.cluster.local
        port:
          number: 80
      headers:
        request:
          set:
            Knative-Serving-Namespace: default
            Knative-Serving-Revision: sample-app-v1

[motocoder-cn]

@sriumcp
can give some help, thanks a lot

[sriumcp]

Hi @ZhengJuCn I believe these configurations are correct (Note: they were removed because Iter8 v0.7 had differences in the experiment spec compared to 0.6; not because the mirroring spec is incorrect; we will reintroduce these examples in 0.8).

The first VS on top says that any query to example.com will simply be sent to the local gateway with its authority header set to example.com. But 40% of this traffic is mirrored. This means Istio will automatically (re)send 40% of this traffic with a new authority header example.com-shadow (to the same route, but that is just a coincidence in this mirroring example). The key is the -shadow extension automatically introduced by the VS for mirroring (see Istio VS documentation for more explanation).

---

The second VS on top does the actual routing of the mirrored and regular traffic to the appropriate Knative service.

[sriumcp]

Incidentally, I am a bit curious about how you plan to collect metrics for your mirrored service. Specifically, how did you instrument the app/service mesh. Could you please provide some insights? This will help make our v0.8 mirroring example a bit more realistic.

[motocoder-cn]

oh, i see.-shadow is magic, istio auto add -shadow， thank you so much