熔断
本任务展示如何为连接、请求以及异常检测配置熔断。
熔断,是创建弹性微服务应用程序的重要模式。熔断能够使您的应用程序具备应对来自故障、潜在峰值和其他 未知网络因素影响的能力。
这个任务中,你将配置熔断规则,然后通过有意的使熔断器“跳闸”来测试配置。
开始之前
- 跟随安装指南安装 Istio。
启动 httpbin 样例程序。
如果您启用了 sidecar 自动注入,通过以下命令部署
httpbin
服务:$ kubectl apply -f @samples/httpbin/httpbin.yaml@
否则,您必须在部署
httpbin
应用程序前进行手动注入,部署命令如下:$ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/httpbin.yaml@)
应用程序 httpbin
作为此任务的后端服务。
配置熔断器
创建一个目标规则,在调用
httpbin
服务时应用熔断设置:$ kubectl apply -f - <<EOF apiVersion: networking.istio.io/v1alpha3 kind: DestinationRule metadata: name: httpbin spec: host: httpbin trafficPolicy: connectionPool: tcp: maxConnections: 1 http: http1MaxPendingRequests: 1 maxRequestsPerConnection: 1 outlierDetection: consecutiveErrors: 1 interval: 1s baseEjectionTime: 3m maxEjectionPercent: 100 EOF
验证目标规则是否已正确创建:
$ kubectl get destinationrule httpbin -o yaml apiVersion: networking.istio.io/v1alpha3 kind: DestinationRule metadata: name: httpbin ... spec: host: httpbin trafficPolicy: connectionPool: http: http1MaxPendingRequests: 1 maxRequestsPerConnection: 1 tcp: maxConnections: 1 outlierDetection: baseEjectionTime: 180.000s consecutiveErrors: 1 interval: 1.000s maxEjectionPercent: 100
增加一个客户
创建客户端程序以发送流量到 httpbin
服务。这是一个名为 Fortio
的负载测试客户的,其可以控制连接数、并发数及发送 HTTP 请求的延迟。通过 Fortio 能够有效的触发前面
在 DestinationRule
中设置的熔断策略。
向客户端注入 Istio Sidecar 代理,以便 Istio 对其网络交互进行管理:
$ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/sample-client/fortio-deploy.yaml@)
登入客户端 Pod 并使用 Fortio 工具调用
httpbin
服务。-curl
参数表明发送一次调用:$ FORTIO_POD=$(kubectl get pod | grep fortio | awk '{ print $1 }') $ kubectl exec -it $FORTIO_POD -c fortio -- /usr/bin/fortio load -curl http://httpbin:8000/get HTTP/1.1 200 OK server: envoy date: Tue, 16 Jan 2018 23:47:00 GMT content-type: application/json access-control-allow-origin: * access-control-allow-credentials: true content-length: 445 x-envoy-upstream-service-time: 36 { "args": {}, "headers": { "Content-Length": "0", "Host": "httpbin:8000", "User-Agent": "istio/fortio-0.6.2", "X-B3-Sampled": "1", "X-B3-Spanid": "824fbd828d809bf4", "X-B3-Traceid": "824fbd828d809bf4", "X-Ot-Span-Context": "824fbd828d809bf4;824fbd828d809bf4;0000000000000000", "X-Request-Id": "1ad2de20-806e-9622-949a-bd1d9735a3f4" }, "origin": "127.0.0.1", "url": "http://httpbin:8000/get" }
可以看到调用后端服务的请求已经成功!接下来,可以测试熔断。
触发熔断器
在 DestinationRule
配置中,您定义了 maxConnections: 1
和 http1MaxPendingRequests: 1
。
这些规则意味着,如果并发的连接和请求数超过一个,在 istio-proxy
进行进一步的请求和连接时,后续请求或
连接将被阻止。
发送并发数为 2 的连接(
-c 2
),请求 20 次(-n 20
):$ kubectl exec -it $FORTIO_POD -c fortio -- /usr/bin/fortio load -c 2 -qps 0 -n 20 -loglevel Warning http://httpbin:8000/get Fortio 0.6.2 running at 0 queries per second, 2->2 procs, for 5s: http://httpbin:8000/get Starting at max qps with 2 thread(s) [gomax 2] for exactly 20 calls (10 per thread + 0) 23:51:10 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) Ended after 106.474079ms : 20 calls. qps=187.84 Aggregated Function Time : count 20 avg 0.010215375 +/- 0.003604 min 0.005172024 max 0.019434859 sum 0.204307492 # range, mid point, percentile, count >= 0.00517202 <= 0.006 , 0.00558601 , 5.00, 1 > 0.006 <= 0.007 , 0.0065 , 20.00, 3 > 0.007 <= 0.008 , 0.0075 , 30.00, 2 > 0.008 <= 0.009 , 0.0085 , 40.00, 2 > 0.009 <= 0.01 , 0.0095 , 60.00, 4 > 0.01 <= 0.011 , 0.0105 , 70.00, 2 > 0.011 <= 0.012 , 0.0115 , 75.00, 1 > 0.012 <= 0.014 , 0.013 , 90.00, 3 > 0.016 <= 0.018 , 0.017 , 95.00, 1 > 0.018 <= 0.0194349 , 0.0187174 , 100.00, 1 # target 50% 0.0095 # target 75% 0.012 # target 99% 0.0191479 # target 99.9% 0.0194062 Code 200 : 19 (95.0 %) Code 503 : 1 (5.0 %) Response Header Sizes : count 20 avg 218.85 +/- 50.21 min 0 max 231 sum 4377 Response Body/Total Sizes : count 20 avg 652.45 +/- 99.9 min 217 max 676 sum 13049 All done 20 calls (plus 0 warmup) 10.215 ms avg, 187.8 qps
有趣的是,几乎所有的请求都完成了!
istio-proxy
确实允许存在一些误差。Code 200 : 19 (95.0 %) Code 503 : 1 (5.0 %)
将并发连接数提高到 3 个:
$ kubectl exec -it $FORTIO_POD -c fortio -- /usr/bin/fortio load -c 3 -qps 0 -n 30 -loglevel Warning http://httpbin:8000/get Fortio 0.6.2 running at 0 queries per second, 2->2 procs, for 5s: http://httpbin:8000/get Starting at max qps with 3 thread(s) [gomax 2] for exactly 30 calls (10 per thread + 0) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) 23:51:51 W http.go:617> Parsed non ok code 503 (HTTP/1.1 503) Ended after 71.05365ms : 30 calls. qps=422.22 Aggregated Function Time : count 30 avg 0.0053360199 +/- 0.004219 min 0.000487853 max 0.018906468 sum 0.160080597 # range, mid point, percentile, count >= 0.000487853 <= 0.001 , 0.000743926 , 10.00, 3 > 0.001 <= 0.002 , 0.0015 , 30.00, 6 > 0.002 <= 0.003 , 0.0025 , 33.33, 1 > 0.003 <= 0.004 , 0.0035 , 40.00, 2 > 0.004 <= 0.005 , 0.0045 , 46.67, 2 > 0.005 <= 0.006 , 0.0055 , 60.00, 4 > 0.006 <= 0.007 , 0.0065 , 73.33, 4 > 0.007 <= 0.008 , 0.0075 , 80.00, 2 > 0.008 <= 0.009 , 0.0085 , 86.67, 2 > 0.009 <= 0.01 , 0.0095 , 93.33, 2 > 0.014 <= 0.016 , 0.015 , 96.67, 1 > 0.018 <= 0.0189065 , 0.0184532 , 100.00, 1 # target 50% 0.00525 # target 75% 0.00725 # target 99% 0.0186345 # target 99.9% 0.0188793 Code 200 : 19 (63.3 %) Code 503 : 11 (36.7 %) Response Header Sizes : count 30 avg 145.73333 +/- 110.9 min 0 max 231 sum 4372 Response Body/Total Sizes : count 30 avg 507.13333 +/- 220.8 min 217 max 676 sum 15214 All done 30 calls (plus 0 warmup) 5.336 ms avg, 422.2 qps
现在,您将开始看到预期的熔断行为,只有 63.3% 的请求成功,其余的均被熔断器拦截:
Code 200 : 19 (63.3 %) Code 503 : 11 (36.7 %)
查询
istio-proxy
状态以了解更多熔断详情:$ kubectl exec $FORTIO_POD -c istio-proxy -- pilot-agent request GET stats | grep httpbin | grep pending cluster.outbound|80||httpbin.springistio.svc.cluster.local.upstream_rq_pending_active: 0 cluster.outbound|80||httpbin.springistio.svc.cluster.local.upstream_rq_pending_failure_eject: 0 cluster.outbound|80||httpbin.springistio.svc.cluster.local.upstream_rq_pending_overflow: 12 cluster.outbound|80||httpbin.springistio.svc.cluster.local.upstream_rq_pending_total: 39
可以看到
upstream_rq_pending_overflow
值12
,这意味着,目前为止已有 12 个调用被标记为熔断。
清理
清理规则:
$ kubectl delete destinationrule httpbin
下线 httpbin 服务和客户端:
$ kubectl delete deploy httpbin fortio-deploy $ kubectl delete svc httpbin