Add Try Request Timeouts Doc

Signed-off-by: noobwei <[email protected]>

content/en/docs/userguide/try_request_timeouts.md

@@ -0,0 +1,123 @@
+---
+draft: false
+linktitle: Try Request Timeouts
+menu:
+  docs:
+    parent: user guide
+    weight: 8
+title: Try Request Timeouts
+toc: true
+type: docs
+
+
+
+---
+
+### Preparation
+
+1. Make default namespace managed by Kmesh
+
+2. Deploy bookinfo as sample application and sleep as curl client
+
+3. Install service granularity waypoint for reviews service
+
+*The above steps could refer to [Install Waypoint | Kmesh](https://kmesh.net/en/docs/userguide/install_waypoint/#preparation)*
+
+4. And install waypoint for ratings service
+```bash
+istioctl x waypoint apply -n default --name ratings-svc-waypoint
+kubectl label service ratings istio.io/use-waypoint=ratings-svc-waypoint
+kubectl annotate gateway ratings-svc-waypoint sidecar.istio.io/proxyImage=ghcr.io/kmesh-net/waypoint:latest
+```
+
+### Request timeouts
+
+A timeout for HTTP requests can be specified using a timeout field in a route rule. By default, the request timeout is disabled, but in this task you override the `reviews` service timeout to half a second. To see its effect, however, you 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:
+
+```bash
+kubectl apply -f - <<EOF
+apiVersion: networking.istio.io/v1alpha3
+kind: VirtualService
+metadata:
+  name: reviews
+spec:
+  hosts:
+    - reviews
+  http:
+  - route:
+    - destination:
+        host: reviews
+        subset: v2
+EOF
+```
+
+2. Add a 2 second delay to calls to the `ratings` service:
+
+```bash
+kubectl apply -f - <<EOF
+apiVersion: networking.istio.io/v1alpha3
+kind: VirtualService
+metadata:
+  name: ratings
+spec:
+  hosts:
+  - ratings
+  http:
+  - fault:
+      delay:
+        percentage:
+          value: 100
+        fixedDelay: 2s
+    route:
+    - destination:
+        host: ratings
+        subset: v1
+EOF
+```
+
+3. Open the Bookinfo URL `http://$GATEWAY_URL/productpage` in your browser, where `$GATEWAY_URL` is the External IP address of the ingress, as explained in the Bookinfo doc.
+
+You should see the Bookinfo application working normally (with ratings stars displayed), but there is a 2 second delay whenever you refresh the page.
+
+![Request_Timeout1](/docs/user_guide/request_timeout1.png)
+
+4. Now add a half second request timeout for calls to the `reviews` service:
+
+```bash
+kubectl apply -f - <<EOF
+apiVersion: networking.istio.io/v1alpha3
+kind: VirtualService
+metadata:
+  name: reviews
+spec:
+  hosts:
+  - reviews
+  http:
+  - route:
+    - destination:
+        host: reviews
+        subset: v2
+    timeout: 0.5s
+EOF
+```
+5. Refresh the Bookinfo web page. You should now see that it returns in about 1 second, instead of 2, and the reviews are unavailable.
+![Request_Timeout2](/docs/user_guide/request_timeout2.png)
+
+### Understanding what happened
+
+In this task, you used Kmesh to set the request timeout for calls to the `reviews` microservice to half a second. By default the request timeout is disabled. Since the `reviews` service subsequently calls the `ratings` service when handling requests, you used Kmesh 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 `reviews` service.
+
+If you examine the [fault injection task](https://kmesh.net/en/docs/userguide/try_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. Notice that in this task you used an Kmesh 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.
+
+### Cleanup
+
+1.  Remove the application routing rules:
+```bash
+kubectl delete virtualservice reviews
+kubectl delete virtualservice ratings
+```
+2. If you are not planning to explore any follow-on tasks, refer to the [Install Waypoint/Cleanup](https://kmesh.net/en/docs/userguide/install_waypoint/#cleanup) instructions to shutdown the application.