mirror of https://github.com/istio/istio.io.git
143 lines
4.9 KiB
Markdown
143 lines
4.9 KiB
Markdown
---
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title: Setting Request Timeouts
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description: This task shows you how to setup request timeouts in Envoy using Istio.
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weight: 28
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aliases:
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- /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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## 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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* Deploy the [Bookinfo](/docs/examples/bookinfo/) sample application.
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* Initialize the application version routing by running the following command:
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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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A timeout for http requests can be specified using the *httpReqTimeout* field of a routing rule.
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By default, the timeout is 15 seconds, 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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1. Route requests to v2 of the `reviews` service, i.e., a version that calls the `ratings` service:
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{{< text bash >}}
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$ cat <<EOF | kubectl apply -f -
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apiVersion: networking.istio.io/v1alpha3
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kind: VirtualService
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metadata:
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name: reviews
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spec:
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hosts:
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- reviews
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http:
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- route:
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- destination:
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host: reviews
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subset: v2
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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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{{< text bash >}}
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$ cat <<EOF | kubectl apply -f -
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apiVersion: networking.istio.io/v1alpha3
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kind: VirtualService
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metadata:
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name: ratings
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spec:
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hosts:
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- ratings
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http:
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- fault:
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delay:
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percent: 100
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fixedDelay: 2s
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route:
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- destination:
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host: ratings
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subset: v1
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EOF
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{{< /text >}}
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1. Open the Bookinfo URL `http://$GATEWAY_URL/productpage` in your browser.
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You should see the Bookinfo application working normally (with ratings stars displayed),
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but there is a 2 second delay whenever you refresh the page.
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1. Now add a half second request timeout for calls to the `reviews` service:
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{{< text bash >}}
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$ cat <<EOF | kubectl apply -f -
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apiVersion: networking.istio.io/v1alpha3
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kind: VirtualService
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metadata:
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name: reviews
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spec:
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hosts:
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- reviews
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http:
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- route:
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- destination:
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host: reviews
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subset: v2
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timeout: 0.5s
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EOF
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{{< /text >}}
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1. Refresh the Bookinfo web page.
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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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> 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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## 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 instead of the default of 15 seconds.
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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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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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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/#failure-handling-faq).
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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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## Cleanup
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* Remove the application routing rules:
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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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