This task shows you how to setup request timeouts in Envoy using Istio.
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:
Note: This assumes you don’t have any routes set yet. If you’ve already created route rules for the sample, you’ll need to use
createin the following command.
istioctl create -f samples/apps/bookinfo/route-rule-all-v1.yaml
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
Route requests to v2 of the
reviews service, i.e., a version that calls the
cat <<EOF | istioctl replace type: route-rule name: reviews-default spec: destination: reviews.default.svc.cluster.local route: - tags: version: v2 EOF
Add a 2 second delay to calls to the
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
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.
Now add a 1 second request timeout for calls to the
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
Refresh the BookInfo web page
You should now see that it returns in 1 second (instead of 2), but the reviews are unavailable.
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). 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
reviews service to take longer than 1 second to complete and consequently you could see the timeout in action.
You 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 receiving the timeout error from the
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 you 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 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 the timeout is specified in millisecond (instead of second) units.