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Copy edit for Setting Request Timeouts. (#1730) 

Signed-off-by: Stephen Gilson <gilsonsm@google.com>
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Stephen Gilson 2018-07-10 08:29:33 -04:00 committed by Martin Taillefer
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content/docs/tasks/traffic-management/request-timeouts/index.md
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@ -27,12 +27,12 @@ This task shows you how to setup request timeouts in Envoy using Istio.
## Request timeouts ## Request timeouts
A timeout for http requests can be specified using the *httpReqTimeout* field of a routing rule. A timeout for http requests can be specified using the *httpReqTimeout* field of a routing rule.
By default, the timeout is 15 seconds, but in this task we'll override the `reviews` service By default, the timeout is 15 seconds, but in this task you override the `reviews` service
timeout to 1 second. timeout to 1 second.
To see its effect, however, we'll also introduce an artificial 2 second delay in calls To see its effect, however, you also introduce an artificial 2 second delay in calls
to the `ratings` service. to the `ratings` service.
1. Route requests to v2 of the `reviews` service, i.e., a version that calls the `ratings` service 1. Route requests to v2 of the `reviews` service, i.e., a version that calls the `ratings` service:
{{< text bash >}} {{< text bash >}}
$ cat <<EOF | istioctl replace -f - $ cat <<EOF | istioctl replace -f -
@ -74,12 +74,12 @@ to the `ratings` service.
EOF EOF
{{< /text >}} {{< /text >}}
1. Open the Bookinfo URL (http://$GATEWAY_URL/productpage) in your browser 1. Open the Bookinfo URL `http://$GATEWAY_URL/productpage` in your browser.
You should see the Bookinfo application working normally (with ratings stars displayed), You should see the Bookinfo application working normally (with ratings stars displayed),
but there is a 2 second delay whenever you refresh the page. but there is a 2 second delay whenever you refresh the page.
1. Now add a 1 second request timeout for calls to the `reviews` service 1. Now add a 1 second request timeout for calls to the `reviews` service:
{{< text bash >}} {{< text bash >}}
$ cat <<EOF | istioctl replace -f - $ cat <<EOF | istioctl replace -f -
@ -99,44 +99,42 @@ to the `ratings` service.
EOF EOF
{{< /text >}} {{< /text >}}
1. Refresh the Bookinfo web page 1. Refresh the Bookinfo web page.
You should now see that it returns in 1 second (instead of 2), but the reviews are unavailable. You should now see that it returns in 1 second, instead of 2, but the reviews are unavailable.
## Understanding what happened ## Understanding what happened
In this task, you used Istio to set the request timeout for calls to the `reviews` In this task, you used Istio to set the request timeout for calls to the `reviews`
microservice to 1 second (instead of the default 15 seconds). microservice to 1 second instead of the default of 15 seconds.
Since the `reviews` service subsequently calls the `ratings` service when handling requests, Since the `reviews` service subsequently calls the `ratings` service when handling requests,
you used Istio to inject a 2 second delay in calls to `ratings`, so that you would cause the you used Istio to inject a 2 second delay in calls to `ratings` to cause the
`reviews` service to take longer than 1 second to complete and consequently you could see the `reviews` service to take longer than 1 second to complete and consequently you could see the timeout in action.
timeout in action.
You observed that the Bookinfo productpage (which calls the `reviews` service to populate the page), You observed that instead of displaying reviews, the Bookinfo productpage (which calls the `reviews` service to populate the page) displayed
instead of displaying reviews, displayed
the message: Sorry, product reviews are currently unavailable for this book. the message: Sorry, product reviews are currently unavailable for this book.
This was the result of it receiving the timeout error from the `reviews` service. This was the result of it receiving the timeout error from the `reviews` service.
If you check out the [fault injection task](/docs/tasks/traffic-management/fault-injection/), you'll find out that the `productpage` If you examine the [fault injection task](/docs/tasks/traffic-management/fault-injection/), you'll find out that the `productpage`
microservice also has its own application-level timeout (3 seconds) for calls to the `reviews` microservice. microservice also has its own application-level timeout (3 seconds) for calls to the `reviews` microservice.
Notice that in this task we used an Istio route rule to set the timeout to 1 second. Notice that in this task we used an Istio route rule to set the timeout to 1 second.
Had you instead set the timeout to something greater than 3 seconds (e.g., 4 seconds) the timeout Had you instead set the timeout to something greater than 3 seconds (such as 4 seconds) the timeout
would have had no effect since the more restrictive of the two will take precedence. would have had no effect since the more restrictive of the two takes precedence.
More details can be found [here](/docs/concepts/traffic-management/#failure-handling-faq). More details can be found [here](/docs/concepts/traffic-management/#failure-handling-faq).
One more thing to note about timeouts in Istio is that in addition to overriding them in route rules, One more thing to note about timeouts in Istio is that in addition to overriding them in route rules,
as you did in this task, they can also be overridden on a per-request basis if the application adds as you did in this task, they can also be overridden on a per-request basis if the application adds
an "x-envoy-upstream-rq-timeout-ms" header on outbound requests. In the header an `x-envoy-upstream-rq-timeout-ms` header on outbound requests. In the header,
the timeout is specified in millisecond (instead of second) units. the timeout is specified in milliseconds instead of seconds.
## Cleanup ## Cleanup
* Remove the application routing rules. * Remove the application routing rules:
{{< text bash >}} {{< text bash >}}
$ istioctl delete -f @samples/bookinfo/routing/route-rule-all-v1.yaml@ $ istioctl delete -f @samples/bookinfo/routing/route-rule-all-v1.yaml@
{{< /text >}} {{< /text >}}
* If you are not planning to explore any follow-on tasks, refer to the * If you are not planning to explore any follow-on tasks, see the
[Bookinfo cleanup](/docs/examples/bookinfo/#cleanup) instructions [Bookinfo cleanup](/docs/examples/bookinfo/#cleanup) instructions
to shutdown the application. to shutdown the application.