Setting Request Timeouts
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:
$ kubectl apply -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
A timeout for http requests can be specified using the timeout field of the route rule.
By default, the timeout is 15 seconds, but in this task you override the
timeout to 1 second.
To see its effect, however, you also introduce an artificial 2 second delay in calls
Route requests to v2 of the
reviewsservice, i.e., a version that calls the
cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: reviews spec: hosts: - reviews http: - route: - destination: host: reviews subset: v2 EOF
Add a 2 second delay to calls to the
cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: ratings spec: hosts: - ratings http: - fault: delay: percent: 100 fixedDelay: 2s route: - destination: host: ratings subset: v1 EOF
Open the Bookinfo URL
http://$GATEWAY_URL/productpagein 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 half second request timeout for calls to the
cat <<EOF | kubectl apply -f - apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: reviews spec: hosts: - reviews http: - route: - destination: host: reviews subset: v2 timeout: 0.5s EOF
Refresh the Bookinfo web page.
You should now see that it returns in about 1 second, instead of 2, and the reviews are unavailable.
The reason that the response takes 1 second, even though the timeout is configured at half a second, is because there is a hard-coded retry in the
productpageservice, so it calls the timing out
reviewsservice twice before returning.
Understanding what happened
In this task, you used Istio to set the request timeout for calls to the
microservice to half a second instead of the default of 15 seconds.
reviews service subsequently calls the
ratings service when handling requests,
you used Istio to inject a 2 second delay in calls to
ratings to cause the
reviews service to take longer than half a second to complete and consequently you could see the timeout in action.
You observed that instead of displaying reviews, the Bookinfo product page (which calls the
reviews service to populate the page) 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 examine the fault injection task, you’ll find out that the
microservice also has its own application-level timeout (3 seconds) for calls to the
Notice that in this task you used an Istio route rule to set the timeout to half a second.
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 takes 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
x-envoy-upstream-rq-timeout-ms header on outbound requests. In the header,
the timeout is specified in milliseconds instead of seconds.
Remove the application routing rules:
$ kubectl delete -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
If you are not planning to explore any follow-on tasks, see the Bookinfo cleanup instructions to shutdown the application.
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