Istio：超时策略（针对VirtualService）

在前面章节的学习中，我们了解到，天气预报应用中frontend会调用forecast，而forecast会调用recommendation

istio-13

那么，我们就依据此调用关系，来设置一个超时策略，比如将超时策略设置在frontend和forecast中间，然后在forecast和recommendation中间设置一个延迟注入的策略，来模拟超时。

1、设置超时策略

[root@master01 ~]# cd /root/cloud-native-istio/11_traffic-management/11.6
[root@master01 11.6]# kubectl apply -f vs-forecast-timeout.yaml -n weather

查看策略

[root@master01 11.6]# kubectl get vs forecast-route -n weather -o yaml
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"networking.istio.io/v1alpha3","kind":"VirtualService","metadata":{"annotations":{},"name":"forecast-route","namespace":"weather"},"spec":{"hosts":["forecast"],"http":[{"route":[{"destination":{"host":"forecast","subset":"v2"}}],"timeout":"1s"}]}}
  creationTimestamp: "2023-11-09T01:59:22Z"
  generation: 5
  name: forecast-route
  namespace: weather
  resourceVersion: "1197197"
  uid: 37e35b32-7449-4c5f-832a-178fe1a55583
spec:
  hosts:
  - forecast
  http:
  - route:
    - destination:
        host: forecast
        subset: v2
    timeout: 1s

到frontend的pod里，curl访问forecast进行测试

[root@master01 11.6]# kubectl -n weather exec -it `kubectl get po -n weather|grep frontend-v1|awk '{print $1}'` -- bash -c 'curl -I http://forecast:3002/weather?locate=hangzhou'
HTTP/1.1 200 OK
content-type: application/json; charset=utf-8
content-length: 665
date: Sat, 11 Nov 2023 02:52:51 GMT
x-envoy-upstream-service-time: 48
server: envoy

说明：由于该请求返回时间远远少于1s，所以状态码为200，是正常的。

2、注入延迟策略

[root@master01 ~]# cd /root/cloud-native-istio/11_traffic-management/11.6
[root@master01 11.6]# kubectl apply -f vs-recommendation-fault-delay.yaml -n weather

查看策略

[root@master01 11.6]# kubectl get vs recommendation-route -n weather -o yaml
apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"networking.istio.io/v1alpha3","kind":"VirtualService","metadata":{"annotations":{},"name":"recommendation-route","namespace":"weather"},"spec":{"hosts":["recommendation"],"http":[{"fault":{"delay":{"fixedDelay":"4s","percentage":{"value":100}}},"route":[{"destination":{"host":"recommendation","subset":"v1"}}]}]}}
  creationTimestamp: "2023-11-09T02:26:09Z"
  generation: 2
  name: recommendation-route
  namespace: weather
  resourceVersion: "1197482"
  uid: f5cb6910-5016-4279-8879-7431dc8a561b
spec:
  hosts:
  - recommendation
  http:
  - fault:
      delay:
        fixedDelay: 4s
        percentage:
          value: 100
    route:
    - destination:
        host: recommendation
        subset: v1

到frontend的pod里，curl访问forecast再次进行测试

[root@master01 11.6]# kubectl -n weather exec -it `kubectl get po -n weather|grep frontend-v1|awk '{print $1}'` -- bash -c 'curl -I http://forecast:3002/weather?locate=hangzhou'
HTTP/1.1 504 Gateway Timeout
content-length: 24
content-type: text/plain
date: Sat, 11 Nov 2023 02:54:22 GMT
server: envoy

说明：超过了1s，直接返回504状态码，而不会等待4s。

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