8.6　超时

Istio通过设置VirtualService中的timeout字段来指定服务的调用超时时间。

使用示例如下：

---

1 apiVersion: networking.istio.io/v1alpha3
 2 kind: VirtualService
 3 metadata:
 4   name: service-node
 5 spec:
 6   hosts:
 7   - service-node
 8   http:
 9   - route:
10     - destination:
11       host: service-node
12     timeout: 500ms

---

第12行指定服务的调用时间不能超过500毫秒，当调用service-node服务时，如果超过500毫秒请求还没有完成，就直接给调用方返回超时错误。

【实验】

1）部署service-node服务：

---

$ kubectl apply -f service/node/service-node.yaml
$ kubectl get pod
NAME                                 READY     STATUS      RESTARTS     AGE
service-go-v1-7cc5c6f574-lrp2h       2/2       Running     0            4m
service-go-v2-7656dcc478-svn5c       2/2       Running     0            4m
service-node-v1-d44b9bf7b-ppn26      2/2       Running     0            24s
service-node-v2-86545d9796-rgmb7     2/2       Running     0            24s

---

2）启动用于并发测试的Pod：

---

$ kubectl apply -f kubernetes/fortio.yaml

---

3）创建service-node服务的超时规则：

---

$ kubectl apply -f istio/resilience/virtual-service-node-timeout.yaml

---

4）访问service-node服务：

---

$ kubectl exec fortio -c fortio /usr/local/bin/fortio -- load -curl http://service-node/env
HTTP/1.1 200 OK
content-type: application/json; charset=utf-8
content-length: 77
date: Wed, 16 Jan 2019 10:33:57 GMT
x-envoy-upstream-service-time: 18
server: envoy
{"message":"node v1","upstream":[{"message":"go v1","response_time":"0.01"}]}
# 10 并发


$ kubectl exec fortio -c fortio /usr/local/bin/fortio -- load -c 10 -qps 0 -n 100 -loglevel Error http://service-node/env
11:08:24 I logger.go:97> Log level is now 4 Error (was 2 Info)
Fortio 1.0.1 running at 0 queries per second, 2->2 procs, for 100 calls: http://service-node/env
Aggregated Function Time : count 100 avg 0.19270902 +/- 0.1403 min 0.009657651 max 0.506141264 sum 19.2709017
# target 50% 0.173333
# target 75% 0.3
# target 90% 0.421429
# target 99% 0.505118
# target 99.9% 0.506039
Sockets used: 15 (for perfect keepalive, would be 10)
Code 200 : 94 (94.0 %)
Code 504 : 6 (6.0 %)
All done 100 calls (plus 0 warmup) 192.709 ms avg, 45.4 qps
# 20 并发


$ kubectl exec fortio -c fortio /usr/local/bin/fortio -- load -c 20 -qps 0 -n 200 -loglevel Error http://service-node/env
11:08:47 I logger.go:97> Log level is now 4 Error (was 2 Info)
Fortio 1.0.1 running at 0 queries per second, 2->2 procs, for 200 calls: http://service-node/env
Aggregated Function Time : count 200 avg 0.44961158 +/- 0.122 min 0.006904922 max 0.524347684 sum 89.9223153
# target 50% 0.50864
# target 75% 0.516494
# target 90% 0.521206
# target 99% 0.524034
# target 99.9% 0.524316
Sockets used: 163 (for perfect keepalive, would be 20)
Code 200 : 46 (23.0 %)
Code 504 : 154 (77.0 %)
All done 200 calls (plus 0 warmup) 449.612 ms avg, 39.2 qps

---

当并发逐渐增大时，service-node服务的响应时间逐渐增大，服务请求响应超时的响应码（504）所占比例逐渐升高。这说明我们配置的服务超时时间已经生效。

5）清理：

---

$ kubectl delete -f kubernetes/fortio.yaml
$ kubectl delete -f service/node/service-node.yaml
$ kubectl delete -f istio/resilience/virtual-service-node-timeout.yaml

---