mirror of https://github.com/istio/istio.io.git
275 lines
12 KiB
Markdown
275 lines
12 KiB
Markdown
---
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title: 熔断
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description: 本任务展示如何为连接、请求以及异常检测配置熔断。
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weight: 50
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keywords: [traffic-management,circuit-breaking]
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owner: istio/wg-networking-maintainers
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test: yes
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---
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本任务展示如何为连接、请求以及异常检测配置熔断。
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熔断，是创建弹性微服务应用程序的重要模式。
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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。
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这个任务中，您将配置熔断规则，然后通过有意的使熔断器“跳闸”来测试配置。
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## 开始之前 {#before-you-begin}
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* 跟随[安装指南](/zh/docs/setup/)安装 Istio。
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{{< boilerplate start-httpbin-service >}}
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应用程序 `httpbin` 作为此任务的后端服务。
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## 配置熔断器 {#configuring-the-circuit-breaker}
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1. 创建一个[目标规则](/zh/docs/reference/config/networking/destination-rule/)，
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在调用 `httpbin` 服务时应用熔断设置：
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{{< warning >}}
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如果您的 Istio 启用了双向 TLS 身份验证，则必须在应用目标规则之前将 TLS 流量策略
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`mode：ISTIO_MUTUAL` 添加到 `DestinationRule`。否则请求将产生 503 错误，
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如[这里](/zh/docs/ops/common-problems/network-issues/#service-unavailable-errors-after-setting-destination-rule)所述。
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{{< /warning >}}
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{{< text bash >}}
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$ kubectl apply -f - <<EOF
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apiVersion: networking.istio.io/v1
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kind: DestinationRule
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metadata:
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name: httpbin
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spec:
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host: httpbin
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trafficPolicy:
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connectionPool:
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tcp:
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maxConnections: 1
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http:
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http1MaxPendingRequests: 1
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maxRequestsPerConnection: 1
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outlierDetection:
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consecutive5xxErrors: 1
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interval: 1s
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baseEjectionTime: 3m
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maxEjectionPercent: 100
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EOF
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{{< /text >}}
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1. 验证目标规则是否已正确创建：
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{{< text bash yaml >}}
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$ kubectl get destinationrule httpbin -o yaml
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apiVersion: networking.istio.io/v1
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kind: DestinationRule
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...
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spec:
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host: httpbin
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trafficPolicy:
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connectionPool:
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http:
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http1MaxPendingRequests: 1
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maxRequestsPerConnection: 1
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tcp:
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maxConnections: 1
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outlierDetection:
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baseEjectionTime: 3m
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consecutive5xxErrors: 1
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interval: 1s
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maxEjectionPercent: 100
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{{< /text >}}
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## 增加一个客户端 {#adding-a-client}
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创建客户端程序以发送流量到 `httpbin` 服务。这是一个名为
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[Fortio](https://github.com/istio/fortio) 的负载测试客户端，
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它可以控制连接数、并发数及发送 HTTP 请求的延迟。
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通过 Fortio 能够有效的触发前面在 `DestinationRule` 中设置的熔断策略。
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1. 向客户端注入 Istio Sidecar 代理，以便 Istio 对其网络交互进行管理：
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如果您启用了[自动注入 Sidecar](/zh/docs/setup/additional-setup/sidecar-injection/#automatic-sidecar-injection)，
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可以直接部署 `fortio` 应用：
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{{< text bash >}}
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$ kubectl apply -f @samples/httpbin/sample-client/fortio-deploy.yaml@
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{{< /text >}}
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否则，您需要在部署 `fortio` 应用前手动注入 Sidecar：
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{{< text bash >}}
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$ kubectl apply -f <(istioctl kube-inject -f @samples/httpbin/sample-client/fortio-deploy.yaml@)
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{{< /text >}}
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1. 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：
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{{< text bash >}}
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$ export FORTIO_POD=$(kubectl get pods -l app=fortio -o 'jsonpath={.items[0].metadata.name}')
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$ kubectl exec "$FORTIO_POD" -c fortio -- /usr/bin/fortio curl -quiet http://httpbin:8000/get
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HTTP/1.1 200 OK
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server: envoy
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date: Tue, 25 Feb 2020 20:25:52 GMT
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content-type: application/json
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content-length: 586
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access-control-allow-origin: *
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access-control-allow-credentials: true
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x-envoy-upstream-service-time: 36
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{
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"args": {},
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"headers": {
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"Content-Length": "0",
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"Host": "httpbin:8000",
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"User-Agent": "fortio.org/fortio-1.3.1",
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"X-B3-Parentspanid": "8fc453fb1dec2c22",
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"X-B3-Sampled": "1",
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"X-B3-Spanid": "071d7f06bc94943c",
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"X-B3-Traceid": "86a929a0e76cda378fc453fb1dec2c22",
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"X-Forwarded-Client-Cert": "By=spiffe://cluster.local/ns/default/sa/httpbin;Hash=68bbaedefe01ef4cb99e17358ff63e92d04a4ce831a35ab9a31d3c8e06adb038;Subject=\"\";URI=spiffe://cluster.local/ns/default/sa/default"
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},
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"origin": "127.0.0.1",
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"url": "http://httpbin:8000/get"
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}
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{{< /text >}}
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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。
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## 触发熔断器 {#tripping-the-circuit-breaker}
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在 `DestinationRule` 配置中，您定义了 `maxConnections: 1` 和 `http1MaxPendingRequests: 1`。
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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。
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1. 发送并发数为 2 的连接（`-c 2`），请求 20 次（`-n 20`）：
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{{< text bash >}}
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$ kubectl exec "$FORTIO_POD" -c fortio -- /usr/bin/fortio load -c 2 -qps 0 -n 20 -loglevel Warning http://httpbin:8000/get
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20:33:46 I logger.go:97> Log level is now 3 Warning (was 2 Info)
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Fortio 1.3.1 running at 0 queries per second, 6->6 procs, for 20 calls: http://httpbin:8000/get
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Starting at max qps with 2 thread(s) [gomax 6] for exactly 20 calls (10 per thread + 0)
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20:33:46 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:33:47 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:33:47 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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Ended after 59.8524ms : 20 calls. qps=334.16
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Aggregated Function Time : count 20 avg 0.0056869 +/- 0.003869 min 0.000499 max 0.0144329 sum 0.113738
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# range, mid point, percentile, count
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>= 0.000499 <= 0.001 , 0.0007495 , 10.00, 2
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> 0.001 <= 0.002 , 0.0015 , 15.00, 1
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> 0.003 <= 0.004 , 0.0035 , 45.00, 6
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> 0.004 <= 0.005 , 0.0045 , 55.00, 2
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> 0.005 <= 0.006 , 0.0055 , 60.00, 1
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> 0.006 <= 0.007 , 0.0065 , 70.00, 2
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> 0.007 <= 0.008 , 0.0075 , 80.00, 2
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> 0.008 <= 0.009 , 0.0085 , 85.00, 1
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> 0.011 <= 0.012 , 0.0115 , 90.00, 1
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> 0.012 <= 0.014 , 0.013 , 95.00, 1
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> 0.014 <= 0.0144329 , 0.0142165 , 100.00, 1
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# target 50% 0.0045
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# target 75% 0.0075
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# target 90% 0.012
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# target 99% 0.0143463
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# target 99.9% 0.0144242
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Sockets used: 4 (for perfect keepalive, would be 2)
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Code 200 : 17 (85.0 %)
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Code 503 : 3 (15.0 %)
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Response Header Sizes : count 20 avg 195.65 +/- 82.19 min 0 max 231 sum 3913
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Response Body/Total Sizes : count 20 avg 729.9 +/- 205.4 min 241 max 817 sum 14598
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All done 20 calls (plus 0 warmup) 5.687 ms avg, 334.2 qps
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{{< /text >}}
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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。
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{{< text plain >}}
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Code 200 : 17 (85.0 %)
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Code 503 : 3 (15.0 %)
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{{< /text >}}
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1. 将并发连接数提高到 3 个：
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{{< text bash >}}
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$ kubectl exec "$FORTIO_POD" -c fortio -- /usr/bin/fortio load -c 3 -qps 0 -n 30 -loglevel Warning http://httpbin:8000/get
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20:32:30 I logger.go:97> Log level is now 3 Warning (was 2 Info)
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Fortio 1.3.1 running at 0 queries per second, 6->6 procs, for 30 calls: http://httpbin:8000/get
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Starting at max qps with 3 thread(s) [gomax 6] for exactly 30 calls (10 per thread + 0)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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20:32:30 W http_client.go:679> Parsed non ok code 503 (HTTP/1.1 503)
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Ended after 51.9946ms : 30 calls. qps=576.98
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Aggregated Function Time : count 30 avg 0.0040001633 +/- 0.003447 min 0.0004298 max 0.015943 sum 0.1200049
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# range, mid point, percentile, count
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>= 0.0004298 <= 0.001 , 0.0007149 , 16.67, 5
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> 0.001 <= 0.002 , 0.0015 , 36.67, 6
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> 0.002 <= 0.003 , 0.0025 , 50.00, 4
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> 0.003 <= 0.004 , 0.0035 , 60.00, 3
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> 0.004 <= 0.005 , 0.0045 , 66.67, 2
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> 0.005 <= 0.006 , 0.0055 , 76.67, 3
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> 0.006 <= 0.007 , 0.0065 , 83.33, 2
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> 0.007 <= 0.008 , 0.0075 , 86.67, 1
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> 0.008 <= 0.009 , 0.0085 , 90.00, 1
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> 0.009 <= 0.01 , 0.0095 , 96.67, 2
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> 0.014 <= 0.015943 , 0.0149715 , 100.00, 1
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# target 50% 0.003
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# target 75% 0.00583333
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# target 90% 0.009
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# target 99% 0.0153601
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# target 99.9% 0.0158847
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Sockets used: 20 (for perfect keepalive, would be 3)
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Code 200 : 11 (36.7 %)
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Code 503 : 19 (63.3 %)
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Response Header Sizes : count 30 avg 84.366667 +/- 110.9 min 0 max 231 sum 2531
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Response Body/Total Sizes : count 30 avg 451.86667 +/- 277.1 min 241 max 817 sum 13556
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All done 30 calls (plus 0 warmup) 4.000 ms avg, 577.0 qps
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{{< /text >}}
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现在，您将开始看到预期的熔断行为，只有 36.7% 的请求成功，其余的均被熔断器拦截：
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{{< text plain >}}
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Code 200 : 11 (36.7 %)
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Code 503 : 19 (63.3 %)
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{{< /text >}}
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1. 查询 `istio-proxy` 状态以了解更多熔断详情:
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{{< text bash >}}
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$ kubectl exec "$FORTIO_POD" -c istio-proxy -- pilot-agent request GET stats | grep httpbin | grep pending
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.circuit_breakers.default.remaining_pending: 1
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.circuit_breakers.default.rq_pending_open: 0
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.circuit_breakers.high.rq_pending_open: 0
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.upstream_rq_pending_active: 0
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.upstream_rq_pending_failure_eject: 0
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.upstream_rq_pending_overflow: 21
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cluster.outbound|8000||httpbin.default.svc.cluster.local;.upstream_rq_pending_total: 29
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{{< /text >}}
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可以看到 `upstream_rq_pending_overflow` 值 `21`，这意味着，目前为止已有 21 个调用被标记为熔断。
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## 清理 {#cleaning-up}
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1. 清理规则:
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{{< text bash >}}
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$ kubectl delete destinationrule httpbin
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{{< /text >}}
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1. 下线 [httpbin]({{< github_tree >}}/samples/httpbin) 服务和客户端：
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{{< text bash >}}
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$ kubectl delete -f @samples/httpbin/sample-client/fortio-deploy.yaml@
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$ kubectl delete -f @samples/httpbin/httpbin.yaml@
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{{< /text >}}
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