Istio 超时处理 (TrafficManagement - Timeout)

超时是为了解决长时间或者无限期的等待造成服务不可用，通常需要在代码中植入此类的网络层面的弹性处理逻辑，但通过 Istio 就可以使用 Vitual Sevice来优雅的实现超时的处理。

什么场景需要用到超时处理

在生产环境中经常会碰到由于调用方等待下游的响应过长，堆积大量的请求阻塞了自身服务，造成雪崩的情况，通过通过超时处理来避免由于无限期等待造成的故障，进而增强服务的可用性。

通过例子来理解

nginx 服务设置了超时时间为3秒，如果超出这个时间就不在等待，返回超时错误
httpd 服务设置了响应时间延迟5秒，任何请求都需要等待5秒后才能返回
client 通过访问 nginx 服务去反向代理 httpd 服务，由于 httpd 服务需要5秒后才能返回，但nginx 服务只等待3秒，所以客户端会提示超时错误

apiVersion: apps/v1
kind: Deployment
metadata:
  labels: app: nginx-deployment
  name: nginx-deployment
spec:
  replicas: 1
  selector: matchLabels: app: nginx-deployment
  strategy: rollingUpdate: maxSurge: 25% maxUnavailable: 25% type: RollingUpdate
  template: metadata: labels: app: nginx-deployment spec: containers: - image: 'nginx:latest' name: nginx-deployment
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels: app: httpd-deployment
  name: httpd-deployment
spec:
  replicas: 1
  selector: matchLabels: app: httpd-deployment
  strategy: rollingUpdate: maxSurge: 25% maxUnavailable: 25% type: RollingUpdate
  template: metadata: labels: app: httpd-deployment spec: containers: - image: 'httpd:latest' name: httpd-deployment
---
apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector: app: nginx-deployment
  type: ClusterIP
  ports:
  - name: http port: 80 targetPort: 80 protocol: TCP
---
apiVersion: v1
kind: Service
metadata:
  name: httpd-service
spec:
  selector: app: httpd-deployment
  type: ClusterIP
  ports:
  - name: http port: 80 targetPort: 80 protocol: TCP
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: nginx-vs
spec:
  hosts:
  - nginx-service
  http:
  - route: - destination: host: nginx-service timeout: 3s
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: httpd-vs
spec:
  hosts:
  - httpd-service
  http:
  - fault: delay: percentage: value: 100 fixedDelay: 5s route: - destination: host: httpd-service
---
apiVersion: apps/v1
kind: Deployment
metadata:
  labels: app: client-deployment
  name: client-deployment
spec:
  replicas: 1
  selector: matchLabels: app: client-deployment
  strategy: rollingUpdate: maxSurge: 25% maxUnavailable: 25% type: RollingUpdate
  template: metadata: labels: app: client-deployment spec: containers: - image: 'busybox:latest' name: client-deployment command: [ "/bin/sh", "-c", "sleep 3600"]

  
 

  
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配置 nginx 反向代理 模拟下游调用

kubectl exec -it nginx-deployment-56c94b9957-xgw88 -- sh

tee /etc/nginx/conf.d/default.conf <<-'EOF'
server { listen 80; server_name localhost; location / { proxy_pass http://httpd-service; proxy_http_version 1.1; }
}
EOF

  
 

  
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执行 nginx -t ; nginx -s reload 重启服务以生效配置

进入客户端容器测试结果

kubectl exec -it client-deployment-56c94b9957-xgw88 -- sh
while true; do wget -q -O - http://nginx-service; done

每隔3秒，由于 nginx 服务的超时时间到了而 httpd 未有响应，则提示返回超时错误。

文章来源: blog.csdn.net，作者：叶康铭，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/m0_38030719/article/details/108940200