镜像

此任务演示了 Istio 的流量镜像功能。

流量镜像,也称为影子流量,是一个以尽可能低的风险为生产带来变化的强大的功能。镜像会将实时流量的副本发送到镜像服务。镜像流量发生在主服务的关键请求路径之外。

在此任务中,首先把流量全部路由到 v1 版本的测试服务。然后,执行规则将一部分流量镜像到 v2 版本。

开始之前

  • 按照安装指南中的说明设置 Istio。

  • 首先部署两个版本的 httpbin 服务,httpbin 服务已开启访问日志:

    httpbin-v1:

    $ cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: httpbin-v1
    spec:
      replicas: 1
      selector:
        matchLabels:
          app: httpbin
          version: v1
      template:
        metadata:
          labels:
            app: httpbin
            version: v1
        spec:
          containers:
          - image: docker.io/kennethreitz/httpbin
            imagePullPolicy: IfNotPresent
            name: httpbin
            command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:80", "httpbin:app"]
            ports:
            - containerPort: 80
    EOF
    

    httpbin-v2:

    $ cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: httpbin-v2
    spec:
      replicas: 1
      selector:
        matchLabels:
          app: httpbin
          version: v2
      template:
        metadata:
          labels:
            app: httpbin
            version: v2
        spec:
          containers:
          - image: docker.io/kennethreitz/httpbin
            imagePullPolicy: IfNotPresent
            name: httpbin
            command: ["gunicorn", "--access-logfile", "-", "-b", "0.0.0.0:80", "httpbin:app"]
            ports:
            - containerPort: 80
    EOF
    

    httpbin Kubernetes service:

    $ kubectl create -f - <<EOF
    apiVersion: v1
    kind: Service
    metadata:
      name: httpbin
      labels:
        app: httpbin
    spec:
      ports:
      - name: http
        port: 8000
        targetPort: 80
      selector:
        app: httpbin
    EOF
    
  • 启动 sleep 服务,这样就可以使用 curl 来提供负载了:

    sleep service:

    $ cat <<EOF | istioctl kube-inject -f - | kubectl create -f -
    apiVersion: apps/v1
    kind: Deployment
    metadata:
      name: sleep
    spec:
      replicas: 1
      selector:
        matchLabels:
          app: sleep
      template:
        metadata:
          labels:
            app: sleep
        spec:
          containers:
          - name: sleep
            image: tutum/curl
            command: ["/bin/sleep","infinity"]
            imagePullPolicy: IfNotPresent
    EOF
    

创建一个默认路由策略

默认情况下,Kubernetes 在 httpbin 服务的两个版本之间进行负载均衡。在此步骤中会更改该行为,把所有流量都路由到 v1

  1. 创建一个默认路由规则,将所有流量路由到服务的 v1

    $ kubectl apply -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: VirtualService
    metadata:
      name: httpbin
    spec:
      hosts:
        - httpbin
      http:
      - route:
        - destination:
            host: httpbin
            subset: v1
          weight: 100
    ---
    apiVersion: networking.istio.io/v1alpha3
    kind: DestinationRule
    metadata:
      name: httpbin
    spec:
      host: httpbin
      subsets:
      - name: v1
        labels:
          version: v1
      - name: v2
        labels:
          version: v2
    EOF
    

    现在所有流量都转到httpbin:v1服务。

  2. 向服务发送一下流量:

    $ export SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})
    $ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl  http://httpbin:8000/headers' | python -m json.tool
    {
      "headers": {
        "Accept": "*/*",
        "Content-Length": "0",
        "Host": "httpbin:8000",
        "User-Agent": "curl/7.35.0",
        "X-B3-Sampled": "1",
        "X-B3-Spanid": "eca3d7ed8f2e6a0a",
        "X-B3-Traceid": "eca3d7ed8f2e6a0a",
        "X-Ot-Span-Context": "eca3d7ed8f2e6a0a;eca3d7ed8f2e6a0a;0000000000000000"
      }
    }
    
  3. 分别查看 httpbin 服务 v1v2 两个 pods 的日志,您可以看到访问日志进入 v1,而 v2 中没有日志,显示为 <none>

    $ export V1_POD=$(kubectl get pod -l app=httpbin,version=v1 -o jsonpath={.items..metadata.name})
    $ kubectl logs -f $V1_POD -c httpbin
    127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
    
    $ export V2_POD=$(kubectl get pod -l app=httpbin,version=v2 -o jsonpath={.items..metadata.name})
    $ kubectl logs -f $V2_POD -c httpbin
    <none>
    

镜像流量到 v2

  1. 改变流量规则将流量镜像到 v2:

    $ kubectl apply -f - <<EOF
    apiVersion: networking.istio.io/v1alpha3
    kind: VirtualService
    metadata:
      name: httpbin
    spec:
      hosts:
        - httpbin
      http:
      - route:
        - destination:
            host: httpbin
            subset: v1
          weight: 100
        mirror:
          host: httpbin
          subset: v2
        mirror_percent: 100
    EOF
    

    这个路由规则发送 100% 流量到 v1。最后一段表示你将镜像流量到 httpbin:v2 服务。当流量被镜像时,请求将发送到镜像服务中,并在 headers 中的 Host/Authority 属性值上追加 -shadow。例如 cluster-1 变为 cluster-1-shadow

    此外,重点注意这些被镜像的流量是『 即发即弃』 的,就是说镜像请求的响应会被丢弃。

    您可以使用 mirror_percent 属性来设置镜像流量的百分比,而不是镜像全部请求。为了兼容老版本,如果这个属性不存在,将镜像所有流量。

  2. 发送流量:

    $ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl  http://httpbin:8000/headers' | python -m json.tool
    

    现在就可以看到 v1v2 中都有了访问日志。v2 中的访问日志就是由镜像流量产生的,这些请求的实际目标是 v1。

    $ kubectl logs -f $V1_POD -c httpbin
    127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
    127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
    
    $ kubectl logs -f $V2_POD -c httpbin
    127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 361 "-" "curl/7.35.0"
    
  3. 如果要检查流量内部,请在另一个控制台上运行以下命令:

    $ export SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})
    $ export V1_POD_IP=$(kubectl get pod -l app=httpbin,version=v1 -o jsonpath={.items..status.podIP})
    $ export V2_POD_IP=$(kubectl get pod -l app=httpbin,version=v2 -o jsonpath={.items..status.podIP})
    $ kubectl exec -it $SLEEP_POD -c istio-proxy -- sudo tcpdump -A -s 0 host $V1_POD_IP or host $V2_POD_IP
    tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
    listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
    05:47:50.159513 IP sleep-7b9f8bfcd-2djx5.38836 > 10-233-75-11.httpbin.default.svc.cluster.local.80: Flags [P.], seq 4039989036:4039989832, ack 3139734980, win 254, options [nop,nop,TS val 77427918 ecr 76730809], length 796: HTTP: GET /headers HTTP/1.1
    E..P2.X.X.X.
    .K.
    .K....P..W,.$.......+.....
    ..t.....GET /headers HTTP/1.1
    host: httpbin:8000
    user-agent: curl/7.35.0
    accept: */*
    x-forwarded-proto: http
    x-request-id: 571c0fd6-98d4-4c93-af79-6a2fe2945847
    x-envoy-decorator-operation: httpbin.default.svc.cluster.local:8000/*
    x-b3-traceid: 82f3e0a76dcebca2
    x-b3-spanid: 82f3e0a76dcebca2
    x-b3-sampled: 0
    x-istio-attributes: Cj8KGGRlc3RpbmF0aW9uLnNlcnZpY2UuaG9zdBIjEiFodHRwYmluLmRlZmF1bHQuc3ZjLmNsdXN0ZXIubG9jYWwKPQoXZGVzdGluYXRpb24uc2VydmljZS51aWQSIhIgaXN0aW86Ly9kZWZhdWx0L3NlcnZpY2VzL2h0dHBiaW4KKgodZGVzdGluYXRpb24uc2VydmljZS5uYW1lc3BhY2USCRIHZGVmYXVsdAolChhkZXN0aW5hdGlvbi5zZXJ2aWNlLm5hbWUSCRIHaHR0cGJpbgo6Cgpzb3VyY2UudWlkEiwSKmt1YmVybmV0ZXM6Ly9zbGVlcC03YjlmOGJmY2QtMmRqeDUuZGVmYXVsdAo6ChNkZXN0aW5hdGlvbi5zZXJ2aWNlEiMSIWh0dHBiaW4uZGVmYXVsdC5zdmMuY2x1c3Rlci5sb2NhbA==
    content-length: 0
    
    
    05:47:50.159609 IP sleep-7b9f8bfcd-2djx5.49560 > 10-233-71-7.httpbin.default.svc.cluster.local.80: Flags [P.], seq 296287713:296288571, ack 4029574162, win 254, options [nop,nop,TS val 77427918 ecr 76732809], length 858: HTTP: GET /headers HTTP/1.1
    E.....X.X...
    .K.
    .G....P......l......e.....
    ..t.....GET /headers HTTP/1.1
    host: httpbin-shadow:8000
    user-agent: curl/7.35.0
    accept: */*
    x-forwarded-proto: http
    x-request-id: 571c0fd6-98d4-4c93-af79-6a2fe2945847
    x-envoy-decorator-operation: httpbin.default.svc.cluster.local:8000/*
    x-b3-traceid: 82f3e0a76dcebca2
    x-b3-spanid: 82f3e0a76dcebca2
    x-b3-sampled: 0
    x-istio-attributes: Cj8KGGRlc3RpbmF0aW9uLnNlcnZpY2UuaG9zdBIjEiFodHRwYmluLmRlZmF1bHQuc3ZjLmNsdXN0ZXIubG9jYWwKPQoXZGVzdGluYXRpb24uc2VydmljZS51aWQSIhIgaXN0aW86Ly9kZWZhdWx0L3NlcnZpY2VzL2h0dHBiaW4KKgodZGVzdGluYXRpb24uc2VydmljZS5uYW1lc3BhY2USCRIHZGVmYXVsdAolChhkZXN0aW5hdGlvbi5zZXJ2aWNlLm5hbWUSCRIHaHR0cGJpbgo6Cgpzb3VyY2UudWlkEiwSKmt1YmVybmV0ZXM6Ly9zbGVlcC03YjlmOGJmY2QtMmRqeDUuZGVmYXVsdAo6ChNkZXN0aW5hdGlvbi5zZXJ2aWNlEiMSIWh0dHBiaW4uZGVmYXVsdC5zdmMuY2x1c3Rlci5sb2NhbA==
    x-envoy-internal: true
    x-forwarded-for: 10.233.75.12
    content-length: 0
    
    
    05:47:50.166734 IP 10-233-75-11.httpbin.default.svc.cluster.local.80 > sleep-7b9f8bfcd-2djx5.38836: Flags [P.], seq 1:472, ack 796, win 276, options [nop,nop,TS val 77427925 ecr 77427918], length 471: HTTP: HTTP/1.1 200 OK
    E....3X.?...
    .K.
    .K..P...$....ZH...........
    ..t...t.HTTP/1.1 200 OK
    server: envoy
    date: Fri, 15 Feb 2019 05:47:50 GMT
    content-type: application/json
    content-length: 241
    access-control-allow-origin: *
    access-control-allow-credentials: true
    x-envoy-upstream-service-time: 3
    
    {
      "headers": {
        "Accept": "*/*",
        "Content-Length": "0",
        "Host": "httpbin:8000",
        "User-Agent": "curl/7.35.0",
        "X-B3-Sampled": "0",
        "X-B3-Spanid": "82f3e0a76dcebca2",
        "X-B3-Traceid": "82f3e0a76dcebca2"
      }
    }
    
    05:47:50.166789 IP sleep-7b9f8bfcd-2djx5.38836 > 10-233-75-11.httpbin.default.svc.cluster.local.80: Flags [.], ack 472, win 262, options [nop,nop,TS val 77427925 ecr 77427925], length 0
    E..42.X.X.\.
    .K.
    .K....P..ZH.$.............
    ..t...t.
    05:47:50.167234 IP 10-233-71-7.httpbin.default.svc.cluster.local.80 > sleep-7b9f8bfcd-2djx5.49560: Flags [P.], seq 1:512, ack 858, win 280, options [nop,nop,TS val 77429926 ecr 77427918], length 511: HTTP: HTTP/1.1 200 OK
    E..3..X.>...
    .G.
    .K..P....l....;...........
    ..|...t.HTTP/1.1 200 OK
    server: envoy
    date: Fri, 15 Feb 2019 05:47:49 GMT
    content-type: application/json
    content-length: 281
    access-control-allow-origin: *
    access-control-allow-credentials: true
    x-envoy-upstream-service-time: 3
    
    {
      "headers": {
        "Accept": "*/*",
        "Content-Length": "0",
        "Host": "httpbin-shadow:8000",
        "User-Agent": "curl/7.35.0",
        "X-B3-Sampled": "0",
        "X-B3-Spanid": "82f3e0a76dcebca2",
        "X-B3-Traceid": "82f3e0a76dcebca2",
        "X-Envoy-Internal": "true"
      }
    }
    
    05:47:50.167253 IP sleep-7b9f8bfcd-2djx5.49560 > 10-233-71-7.httpbin.default.svc.cluster.local.80: Flags [.], ack 512, win 262, options [nop,nop,TS val 77427926 ecr 77429926], length 0
    E..4..X.X...
    .K.
    .G....P...;..n............
    ..t...|.
    

    您可以看到流量​​ 的请求和响应内容。

清理

  1. 删除规则:

    $ kubectl delete virtualservice httpbin
    $ kubectl delete destinationrule httpbin
    
  2. 关闭 httpbin 服务和客户端:

    $ kubectl delete deploy httpbin-v1 httpbin-v2 sleep
    $ kubectl delete svc httpbin
    
这些信息有用吗?
Do you have any suggestions for improvement?

Thanks for your feedback!