杂谈容器生态Istio03-任务流量管理
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08-流量镜像

Catalogue
  1. 1. 目标
  2. 2. 部署httpbin
  3. 3. 配置所有流量到http-v1
  4. 4. 测试
  5. 5. 镜像拷贝流量到v2版本
  6. 6. 测试
  7. 7. 清楚测试环境
  8. 8. 参考资料

该篇演示istio的流量镜像能力。

流量镜像就是会将实时流量的副本发送到镜像服务。

目标

  1. 强制所有流量发送到测试服务的v1版本
  2. 应用规则将部分流量镜像到v2

部署httpbin

  1. httpbin-v1
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apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: httpbin-v1
spec:
  replicas: 1
  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
  1. httpbin-v2
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apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: httpbin-v2
spec:
  replicas: 1
  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
  1. httpbin-service，关联到httpbin的v1和v2版本
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apiVersion: v1
kind: Service
metadata:
  name: httpbin
  labels:
    app: httpbin
spec:
  ports:
  - name: http
    port: 8000
    targetPort: 80
  selector:
    app: httpbin
  1. 创建一个sleep服务，测试用
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apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: sleep
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: sleep
    spec:
      containers:
      - name: sleep
        image: tutum/curl
        command: ["/bin/sleep","infinity"]
        imagePullPolicy: IfNotPresent

配置所有流量到http-v1

默认情况下，Kubernetes在两个版本的httpbin服务之间实现负载平衡。

在此步骤中，您将更改该行为，以便所有流量都流向v1。

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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

测试

  1. 发送请求到httpbin
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$ 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


响应：
{
  "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"
  }
}
  1. 查看httpbin的v1和v2版本的日志，会发现只有v1有
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$ export V1_POD=$(kubectl get pod -l app=httpbin,version=v1 -o jsonpath={.items..metadata.name})
$ kubectl logs -f $V1_POD -c httpbin
127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
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$ export V2_POD=$(kubectl get pod -l app=httpbin,version=v2 -o jsonpath={.items..metadata.name})
$ kubectl logs -f $V2_POD -c httpbin
<none>

镜像拷贝流量到v2版本

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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

此路由规则将100％的流量发送到v1。最后一个节指定您要镜像到httpbin：v2服务。当流量被镜像时，请求将通过其主机/授权标头附加-shadow发送到镜像服务。例如，cluster-1变为cluster-1-shadow。 同样，重要的是要注意，这些请求被镜像为“即发即弃”，这意味着响应被丢弃了。

istio-v1.0版本之后，新加了mirror_percent 字段，和mirror同级，值为0-100，指定镜像流量百分比，来替代之前全部流量都镜像。

测试

  1. 发送请求
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$ kubectl exec -it $SLEEP_POD -c sleep -- sh -c 'curl  http://httpbin:8000/headers' | python -m json.tool
  1. 查看请求日志，发现v1和v2都收到请求
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$ kubectl logs -f $V1_POD -c httpbin
127.0.0.1 - - [07/Mar/2018:19:02:43 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 321 "-" "curl/7.35.0"
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$ kubectl logs -f $V2_POD -c httpbin
127.0.0.1 - - [07/Mar/2018:19:26:44 +0000] "GET /headers HTTP/1.1" 200 361 "-" "curl/7.35.0"
  1. 如果要检查流量内部信息，请在另一个控制台上运行以下命令：
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$ export SLEEP_POD=$(kubectl get pod -l app=sleep -o jsonpath={.items..metadata.name})
$ export V1_POD_IP=$(kubectl get pod -l app=httpbin -l version=v1 -o jsonpath={.items..status.podIP})
$ export V2_POD_IP=$(kubectl get pod -l app=httpbin -l 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

清楚测试环境

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$ kubectl delete virtualservice httpbin
$ kubectl delete destinationrule httpbin

$ kubectl delete deploy httpbin-v1 httpbin-v2 sleep
$ kubectl delete svc httpbin

参考资料