Configuring Request Routing
This task shows you how to route requests dynamically to multiple versions of a microservice.
Before you begin
Setup Istio by following the instructions in the Installation guide.
Deploy the Bookinfo sample application.
Review the Traffic Management concepts doc. Before attempting this task, you should be familiar with important terms such as destination rule, virtual service, and subset.
About this task
The Istio Bookinfo sample consists of four separate microservices, each with multiple versions.
Three different versions of one of the microservices,
reviews, have been deployed and are running concurrently.
To illustrate the problem this causes, access the Bookinfo app’s
/productpage in a browser and refresh several times.
You’ll notice that sometimes the book review output contains star ratings and other times it does not.
This is because without an explicit default service version to route to, Istio routes requests to all available versions
in a round robin fashion.
The initial goal of this task is to apply rules that route all traffic to
v1 (version 1) of the microservices. Later, you
will apply a rule to route traffic based on the value of an HTTP request header.
Apply a virtual service
To route to one version only, you apply virtual services that set the default version for the microservices.
In this case, the virtual services will route all traffic to
v1 of each microservice.
Run the following command to apply the virtual services:
$ kubectl apply -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
Because configuration propagation is eventually consistent, wait a few seconds for the virtual services to take effect.
Display the defined routes with the following command:
$ kubectl get virtualservices -o yaml apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: details ... spec: hosts: - details http: - route: - destination: host: details subset: v1 --- apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: productpage ... spec: gateways: - bookinfo-gateway - mesh hosts: - productpage http: - route: - destination: host: productpage subset: v1 --- apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: ratings ... spec: hosts: - ratings http: - route: - destination: host: ratings subset: v1 --- apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: reviews ... spec: hosts: - reviews http: - route: - destination: host: reviews subset: v1 ---
You can also display the corresponding
subsetdefinitions with the following command:
$ kubectl get destinationrules -o yaml
You have configured Istio to route to the
v1 version of the Bookinfo microservices,
most importantly the
reviews service version 1.
Test the new routing configuration
You can easily test the new configuration by once again refreshing the
of the Bookinfo app.
Open the Bookinfo site in your browser. The URL is
$GATEWAY_URLis the External IP address of the ingress, as explained in the Bookinfo doc.
Notice that the reviews part of the page displays with no rating stars, no matter how many times you refresh. This is because you configured Istio to route all traffic for the reviews service to the version
reviews:v1and this version of the service does not access the star ratings service.
You have successfully accomplished the first part of this task: route traffic to one version of a service.
Route based on user identity
Next, you will change the route configuration so that all traffic from a specific user
is routed to a specific service version. In this case, all traffic from a user
named Jason will be routed to the service
Note that Istio doesn’t have any special, built-in understanding of user
identity. This example is enabled by the fact that the
adds a custom
end-user header to all outbound HTTP requests to the reviews
reviews:v2 is the version that includes the star ratings feature.
Run the following command to enable user-based routing:
$ kubectl apply -f @samples/bookinfo/networking/virtual-service-reviews-test-v2.yaml@
Confirm the rule is created:
$ kubectl get virtualservice reviews -o yaml apiVersion: networking.istio.io/v1alpha3 kind: VirtualService metadata: name: reviews ... spec: hosts: - reviews http: - match: - headers: end-user: exact: jason route: - destination: host: reviews subset: v2 - route: - destination: host: reviews subset: v1
/productpageof the Bookinfo app, log in as user
Refresh the browser. What do you see? The star ratings appear next to each review.
Log in as another user (pick any name you wish).
Refresh the browser. Now the stars are gone. This is because traffic is routed to
reviews:v1for all users except Jason.
You have successfully configured Istio to route traffic based on user identity.
Understanding what happened
In this task, you used Istio to send 100% of the traffic to the
of each of the Bookinfo services. You then set a rule to selectively send traffic
v2 of the
reviews service based on a custom
end-user header added
to the request by the
Note that Kubernetes services, like the Bookinfo ones used in this task, must adhere to certain restrictions to take advantage of Istio’s L7 routing features. Refer to the Requirements for Pods and Services for details.
In the traffic shifting task, you will follow the same basic pattern you learned here to configure route rules to gradually send traffic from one version of a service to another.
Remove the application virtual services:
$ kubectl delete -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
If you are not planning to explore any follow-on tasks, refer to the Bookinfo cleanup instructions to shutdown the application.