istio.io/_docs/tasks/request-timeouts.md

title	overview	order	layout	type
Request Timeouts	This task shows you how to setup request timeouts in Envoy using Istio.	40	docs	markdown

This task shows you how to setup request timeouts in Envoy using Istio.

Before you begin

• Setup Istio by following the instructions in the Installation guide.

• Deploy the bookinfo sample application.

• Initialize the application version routing by running the following command:

  istioctl create -f route-rule-all-v1.yaml
  

Request timeouts

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 timeout to 1 second. To see its effect, however, we'll also introduce an artificial 2 second delay in calls to the ratings service.

1. Route requests to v2 of the reviews service, i.e., a version that calls the ratings service

   cat <<EOF | istioctl replace
   type: route-rule
   name: reviews-default
   spec:
     destination: reviews.default.svc.cluster.local
     route:
     - tags:
         version: v2
   EOF
   

2. Add a 2 second delay to calls to the ratings service:

   cat <<EOF | istioctl replace
   type: route-rule
   name: ratings-default
   spec:
     destination: ratings.default.svc.cluster.local
     route:
     - tags:
         version: v1
     httpFault:
       delay:
         percent: 100
         fixedDelay: 2s
   EOF
   

3. Open the Bookinfo URL (http://$GATEWAY_URL/productpage) in your browser

   You should see the bookinfo application working normally (with ratings stars displayed), but there is a 2 second delay whenever you refresh the page.

4. Now add a 1 second request timeout for calls to the reviews service

   cat <<EOF | istioctl replace
   type: route-rule
   name: reviews-default
   spec:
     destination: reviews.default.svc.cluster.local
     route:
     - tags:
         version: v2
     httpReqTimeout:
       simpleTimeout:
         timeout: 1s
   EOF
   

5. Refresh the Bookinfo web page

   You should now see that it returns in 1 second (instead of 2), but the reviews are unavailable.

Understanding what happened

In this task, we used Istio to set the request timeout for calls to the reviews microservice to 1 second (instead of the default 15 seconds). Since the reviews service subsequently calls the ratings service when handling requests, we used Istio to inject a 2 second delay in call to ratings, so that we would cause the reviews service to take longer than 1 second to complete and consequently we coud see the timeout in action.

We observed that the Bookinfo productpage (which calls the reviews service to populate the page), instead of displaying reviews, displayed the message: Sorry, product reviews are currently unavailable for this book. This was the result of it recieving the timeout error from the reviews service.

If you check out the fault injection task, you'll find out that the productpage 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. Had we instead set the timeout to something greater than 3 seconds (e.g., 4 seconds) the timeout would have had no effect since the more restrictive of the two will take precedence. More details can be found here.

One more thing to note about timeouts in Istio is that in addition to overriding them in route rules, as we 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 the timeout is specified in millisecond (instead of second) units.

What's next

• Learn more about failure handling.

• Learn more about routing rules.