istio sidecar envoy 权重比例策略配置

下发如下virtualservice策略，header中包含end-user：jason的请求发reviews的v2版本，其它的请求 50%发往v1，50%发往v2

[root@k8s-master-v1-16 networking]# cat  virtual-service-reviews-jason-weight-istio-bookinfo.yaml
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: reviews
  namespace: istio-bookinfo
spec:
  hosts:
    - reviews
  http:
  - match:
    - headers:
        end-user:
          exact: jason
    route:
    - destination:
        host: reviews
        subset: v2
  - route:
    - destination:
        host: reviews
        subset: v1
      weight: 50
    - destination:
        host: reviews
        subset: v3
      weight: 50

$ istioctl proxy-config route productpage-v1-7f4cc988c6-qxqjs.istio-bookinfo --name 9080 -o json | grep -A 100 '"name": "reviews.istio-bookinfo.svc.cluster.local:9080",'

                "name": "reviews.istio-bookinfo.svc.cluster.local:9080",
                "domains": [
                    "reviews.istio-bookinfo.svc.cluster.local",
                    "reviews.istio-bookinfo.svc.cluster.local:9080",
                    "reviews",
                    "reviews:9080",
                    "reviews.istio-bookinfo.svc.cluster",
                    "reviews.istio-bookinfo.svc.cluster:9080",
                    "reviews.istio-bookinfo.svc",
                    "reviews.istio-bookinfo.svc:9080",
                    "reviews.istio-bookinfo",
                    "reviews.istio-bookinfo:9080",
                    "10.105.236.72",
                    "10.105.236.72:9080"
                ],
                "routes": [
                    {
                        "match": {
                            "prefix": "/",
                            "caseSensitive": true,
                            "headers": [
                                {
                                    "name": "end-user",
                                    "exactMatch": "jason"
                                }
                            ]
                        },
                        "route": {
                            "cluster": "outbound|9080|v2|reviews.istio-bookinfo.svc.cluster.local",
                            "timeout": "0s",
                            "retryPolicy": {
                                "retryOn": "connect-failure,refused-stream,unavailable,cancelled,retriable-status-codes",
                                "numRetries": 2,
                                "retryHostPredicate": [
                                    {
                                        "name": "envoy.retry_host_predicates.previous_hosts"
                                    }
                                ],
                                "hostSelectionRetryMaxAttempts": "5",
                                "retriableStatusCodes": [
                                    503
                                ]
                            },
                            "maxGrpcTimeout": "0s"
                        },
                        "metadata": {
                            "filterMetadata": {
                                "istio": {
                                    "config": "/apis/networking.istio.io/v1alpha3/namespaces/istio-bookinfo/virtual-service/reviews"
                                }
                            }
                        },
                        "decorator": {
                            "operation": "reviews.istio-bookinfo.svc.cluster.local:9080/*"
                        }
                    },
                    {
                        "match": {
                            "prefix": "/"
                        },
                        "route": {
                            "weightedClusters": {
                                "clusters": [
                                    {
                                        "name": "outbound|9080|v1|reviews.istio-bookinfo.svc.cluster.local",
                                        "weight": 50
                                    },
                                    {
                                        "name": "outbound|9080|v3|reviews.istio-bookinfo.svc.cluster.local",
                                        "weight": 50
                                    }
                                ]
                            },
                            "timeout": "0s",
                            "retryPolicy": {
                                "retryOn": "connect-failure,refused-stream,unavailable,cancelled,retriable-status-codes",
                                "numRetries": 2,
                                "retryHostPredicate": [
                                    {
                                        "name": "envoy.retry_host_predicates.previous_hosts"
                                    }
                                ],
                                "hostSelectionRetryMaxAttempts": "5",
                                "retriableStatusCodes": [
                                    503
                                ]
                            },
                            "maxGrpcTimeout": "0s"
                        },
                        "metadata": {
                            "filterMetadata": {
                                "istio": {
                                    "config": "/apis/networking.istio.io/v1alpha3/namespaces/istio-bookinfo/virtual-service/reviews"
                                }
                            }
                        },
                        "decorator": {
                            "operation": "reviews:9080/*"
                        }
                    }
                ],