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ilylia
Istio Automation
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---
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title: Request Timeouts
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description: This task shows you how to setup request timeouts in Envoy using Istio.
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title: 设置请求超时
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description: 本任务用于示范如何使用 Istio 在 Envoy 中设置请求超时。
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weight: 40
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aliases:
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- /docs/tasks/request-timeouts.html
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- /zh/docs/tasks/request-timeouts.html
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keywords: [traffic-management,timeouts]
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---
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This task shows you how to setup request timeouts in Envoy using Istio.
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本任务用于示范如何使用 Istio 在 Envoy 中设置请求超时。
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## Before you begin
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## 开始之前{#before-you-begin}
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* Setup Istio by following the instructions in the
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[Installation guide](/docs/setup/).
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* 按照[安装指南](/zh/docs/setup/)中的说明安装 Istio。
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* Deploy the [Bookinfo](/docs/examples/bookinfo/) sample application including the
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[default destination rules](/docs/examples/bookinfo/#apply-default-destination-rules).
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* 部署示例应用程序 [Bookinfo](/zh/docs/examples/bookinfo/)，并应用[默认目标规则](/zh/docs/examples/bookinfo/#apply-default-destination-rules)。
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* Initialize the application version routing by running the following command:
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* 运行以下命令初始化应用的版本路由：
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{{< text bash >}}
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$ kubectl apply -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
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{{< /text >}}
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## Request timeouts
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## 请求超时{#request-timeouts}
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A timeout for http requests can be specified using the *timeout* field of the [route rule](/docs/reference/config/networking/virtual-service/#HTTPRoute).
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By default, the timeout is disabled, but in this task you override the `reviews` service
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timeout to 1 second.
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To see its effect, however, you also introduce an artificial 2 second delay in calls
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to the `ratings` service.
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http 请求的超时可以用[路由规则](/zh/docs/reference/config/networking/virtual-service/#HTTPRoute)的 *timeout* 字段来指定。
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默认情况下，超时是禁用的，本任务中，会把 `reviews` 服务的超时设置为 1 秒。
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为了观察效果，还需要在对 `ratings` 服务的调用上人为引入 2 秒的延迟。
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1. Route requests to v2 of the `reviews` service, i.e., a version that calls the `ratings` service:
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1. 将请求路由到 `reviews` 服务的 v2 版本，它会发起对 `ratings` 服务的调用：
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{{< text bash >}}
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$ kubectl apply -f - <<EOF
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@ -50,7 +46,7 @@ to the `ratings` service.
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EOF
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{{< /text >}}
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1. Add a 2 second delay to calls to the `ratings` service:
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1. 给对 `ratings` 服务的调用添加 2 秒的延迟：
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{{< text bash >}}
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$ kubectl apply -f - <<EOF
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@ -73,12 +69,11 @@ to the `ratings` service.
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EOF
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{{< /text >}}
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1. Open the Bookinfo URL `http://$GATEWAY_URL/productpage` in your browser.
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1. 在浏览器中打开 Bookinfo 的网址 `http://$GATEWAY_URL/productpage`。
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You should see the Bookinfo application working normally (with ratings stars displayed),
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but there is a 2 second delay whenever you refresh the page.
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这时可以看到 Bookinfo 应用运行正常（显示了评级的星型符号），但是每次刷新页面，都会有 2 秒的延迟。
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1. Now add a half second request timeout for calls to the `reviews` service:
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1. 现在给对 `reviews` 服务的调用增加一个半秒的请求超时：
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{{< text bash >}}
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$ kubectl apply -f - <<EOF
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@ -98,48 +93,38 @@ to the `ratings` service.
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EOF
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{{< /text >}}
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1. Refresh the Bookinfo web page.
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1. 刷新 Bookinfo 页面。
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You should now see that it returns in about 1 second, instead of 2, and the reviews are unavailable.
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这时候应该看到 1 秒钟就会返回，而不是之前的 2 秒钟，但 `reviews` 是不可用的。
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{{< tip >}}
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The reason that the response takes 1 second, even though the timeout is configured at half a second, is
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because there is a hard-coded retry in the `productpage` service, so it calls the timing out `reviews` service
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twice before returning.
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即使超时配置为半秒，响应仍需要 1 秒，是因为 `productpage` 服务中存在硬编码重试，因此它在返回之前调用 `reviews` 服务超时两次。
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{{< /tip >}}
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## Understanding what happened
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## 理解原理{#understanding-what-happened}
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In this task, you used Istio to set the request timeout for calls to the `reviews`
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microservice to half a second. By default the request timeout is disabled.
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Since the `reviews` service subsequently calls the `ratings` service when handling requests,
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you used Istio to inject a 2 second delay in calls to `ratings` to cause the
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`reviews` service to take longer than half a second to complete and consequently you could see the timeout in action.
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本任务中，使用 Istio 为对 `reviews` 微服务的调用配置了半秒的请求超时。默认情况下请求超时是禁用的。
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`reviews` 服务在处理请求时会接着调用 `ratings` 服务，用 Istio 在对 `ratings` 的调用中注入了两秒钟的延迟，这样就让
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`reviews` 服务要花费超过半秒的时间来完成调用，因此可以观察到超时。
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You observed that instead of displaying reviews, the Bookinfo product page (which calls the `reviews` service to populate the page) displayed
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the message: Sorry, product reviews are currently unavailable for this book.
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This was the result of it receiving the timeout error from the `reviews` service.
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可以观察到，Bookinfo 的页面（调用 `reviews` 服务来生成页面）没显示评论，而是显示了消息：
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**Sorry, product reviews are currently unavailable for this book.**
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这就是它收到了来自 `reviews` 服务的超时错误信息。
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If you examine the [fault injection task](/docs/tasks/traffic-management/fault-injection/), you'll find out that the `productpage`
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microservice also has its own application-level timeout (3 seconds) for calls to the `reviews` microservice.
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Notice that in this task you used an Istio route rule to set the timeout to half a second.
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Had you instead set the timeout to something greater than 3 seconds (such as 4 seconds) the timeout
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would have had no effect since the more restrictive of the two takes precedence.
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More details can be found [here](/docs/concepts/traffic-management/#network-resilience-and-testing).
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如果看过[故障注入任务](/zh/docs/tasks/traffic-management/fault-injection/)，就会发现 `productpage`
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微服务在调用 `reviews` 微服务时，还有它自己的应用级的超时（3 秒）设置。
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注意在本任务中使用 Istio 路由规则设置了半秒的超时。
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如果将超时设置为大于 3 秒（比如 4 秒），则超时将不会有任何影响，因为这两个超时的限制性更强。
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更多细节可以参考[这里](/zh/docs/concepts/traffic-management/#network-resilience-and-testing)。
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One more thing to note about timeouts in Istio is that in addition to overriding them in route rules,
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as you did in this task, they can also be overridden on a per-request basis if the application adds
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an `x-envoy-upstream-rq-timeout-ms` header on outbound requests. In the header,
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the timeout is specified in milliseconds instead of seconds.
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还有一点关于 Istio 中超时控制方面的补充说明，除了像本文一样在路由规则中进行超时设置之外，还可以进行请求一级的设置，只需在应用的对外请求中加入 `x-envoy-upstream-rq-timeout-ms` 请求头即可。在这个请求头中的超时设置单位是毫秒而不是秒。
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## Cleanup
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## 清理{#cleanup}
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* Remove the application routing rules:
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* 删除应用程序的路由规则：
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{{< text bash >}}
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$ kubectl delete -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
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{{< /text >}}
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* If you are not planning to explore any follow-on tasks, see the
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[Bookinfo cleanup](/docs/examples/bookinfo/#cleanup) instructions
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to shutdown the application.
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* 如果您不打算探索任何后续任务，请参阅 [Bookinfo 清理](/zh/docs/examples/bookinfo/#cleanup) 的说明关闭应用程序。
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