Istio网络弹性之超时

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1、网络弹性介绍

​ 网络弹性也称为运维弹性，是指网络在遇到灾难事件时快速恢复和继续运行的能力。灾难事件的范畴很广泛，比如长时间停电、网络设备故障、恶意入侵等

2、Istio 超时实例

​ 需要结合 Istio 故障注入模拟被调用方响应请求慢的场景，该实例的架构图如下：

ht

​ 架构说明如下，本实例就是模拟客户端调用 nginx，nginx 将请求转发给 tomcat 的常见功能。tomcat 响应请求设置为 10s（通过故障注入实现，相当于 sleep 10s 逻辑），nginx 设置 client 的请求超时时间为 2s。因为 nginx 需要在 2s 内返回给 client，而 nginx 请求 tomcat 却需要 10s，因此模拟 client 调用 nginx 超时的情景。

2.1 部署客户端

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apiVersion: apps/v1
kind: Deployment
metadata:
  name: client
spec:
  replicas: 1
  selector:
    matchLabels:
      app: client
  template:
    metadata:
      labels:
        app: client
    spec:
      containers:
      - name: busybox
        image: busybox
        imagePullPolicy: IfNotPresent
        command: [ "/bin/sh", "-c", "sleep 3600" ]

2.2 部署nginx和tomcat实例

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apiVersion: v1
kind: Service
metadata:
  name: nginx-svc
spec:
  selector:
    server: nginx
  ports:
  - name: http
    port: 80
    targetPort: 80
    protocol: TCP
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx
  labels:
    server: nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      server: nginx
  template:
    metadata:
      labels:
        server: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14-alpine
        imagePullPolicy: IfNotPresent
---
apiVersion: v1
kind: Service
metadata:
  name: tomcat-svc
spec:
  selector:
    server: tomcat
  ports:
  - name: http
    port: 8080
    targetPort: 8080
    protocol: TCP
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat
  labels:
    server: tomcat
spec:
  replicas: 1
  selector:
    matchLabels:
      server: tomcat
  template:
    metadata:
      labels:
        server: tomcat
    spec:
      containers:
      - name: tomcat
        image: docker.io/kubeguide/tomcat-app:v1
        imagePullPolicy: IfNotPresent

2.3 Istio 虚拟服务资源

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apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: nginx-vs
spec:
  hosts:
  - nginx-svc
  http:
  - route:
    - destination:
        host: nginx-svc
    timeout: 2s
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: tomcat-vs
spec:
  hosts:
  - tomcat-svc
  http:
  - fault:
      delay:
        percentage:
          value: 100
        fixedDelay: 10s
    route:
    - destination:
        host: tomcat-svc

2.4 部署以上示例，并进行istio注入

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istioctl kube-inject -f test-client.yaml | kubectl apply -f -
istioctl kube-inject -f test-deploy.yaml | kubectl apply -f -

image-20200529155003268

3、配置nginx转发tomcat

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kubectl exec -it nginx-579d7f7ff-9pspn /bin/sh
修改完后让配置生效
nginx  -t
nginx  -s  reload

修改内容如下

image-20200529155832030

4、客户端验证

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kubectl exec -it client-8496866cdf-vkmcw /bin/sh
wget -q -O - http://nginx-svc
wget -q -O - http://tomcat-svc:8080

image-20200529160213693

image-20200529160225140

为了实验效果，设置长了时间，和设置的nginx 2s和tomcat 10s是吻合的，除去操作时间