This task shows you how to shift traffic from one version of a microservice to another.
A common use case is to migrate traffic gradually from an older version of a microservice to a new one. In Istio, you accomplish this goal by configuring a sequence of routing rules that redirect a percentage of traffic from one destination to another.
In this task, you will use send 50% of traffic to
reviews:v1 and 50% to
reviews:v3. Then, you will
complete the migration by sending 100% of traffic to
Before you begin
Setup Istio by following the instructions in the Installation guide.
Deploy the Bookinfo sample application.
Review the Traffic Management concepts doc.
Apply weight-based routing
- To get started, run this command to route all traffic to the
$ kubectl apply -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
$ kubectl apply -f @samples/bookinfo/gateway-api/route-reviews-v1.yaml@
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.
Transfer 50% of the traffic from
reviews:v3with the following command:
$ kubectl apply -f @samples/bookinfo/networking/virtual-service-reviews-50-v3.yaml@
$ kubectl apply -f @samples/bookinfo/gateway-api/route-reviews-50-v3.yaml@
- Wait a few seconds for the new rules to propagate and then confirm the rule was replaced:
$ kubectl get virtualservice reviews -o yaml apiVersion: networking.istio.io/v1beta1 kind: VirtualService ... spec: hosts: - reviews http: - route: - destination: host: reviews subset: v1 weight: 50 - destination: host: reviews subset: v3 weight: 50
$ kubectl get httproute reviews -o yaml apiVersion: gateway.networking.k8s.io/v1beta1 kind: HTTPRoute ... spec: parentRefs: - group: gateway.networking.k8s.io kind: Service name: reviews port: 9080 rules: - backendRefs: - group: "" kind: Service name: reviews-v1 port: 9080 weight: 50 - group: "" kind: Service name: reviews-v3 port: 9080 weight: 50 matches: - path: type: PathPrefix value: / status: parents: - conditions: - lastTransitionTime: "2022-11-10T18:13:43Z" message: Route was valid observedGeneration: 14 reason: Accepted status: "True" type: Accepted ...
/productpagein your browser and you now see red colored star ratings approximately 50% of the time. This is because the
reviewsaccesses the star ratings service, but the
v1version does not.
Assuming you decide that the
reviews:v3microservice is stable, you can route 100% of the traffic to
reviews:v3by applying this virtual service:
$ kubectl apply -f @samples/bookinfo/networking/virtual-service-reviews-v3.yaml@
$ kubectl apply -f @samples/bookinfo/gateway-api/route-reviews-v3.yaml@
- Refresh the
/productpageseveral times. Now you will always see book reviews with red colored star ratings for each review.
Understanding what happened
In this task you migrated traffic from an old to new version of the
reviews service using Istio’s weighted routing feature. Note that this is very different than doing version migration using the deployment features of container orchestration platforms, which use instance scaling to manage the traffic.
With Istio, you can allow the two versions of the
reviews service to scale up and down independently, without affecting the traffic distribution between them.
For more information about version routing with autoscaling, check out the blog article Canary Deployments using Istio.
- Remove the application routing rules:
$ kubectl delete -f @samples/bookinfo/networking/virtual-service-all-v1.yaml@
$ kubectl delete httproute reviews
- If you are not planning to explore any follow-on tasks, refer to the Bookinfo cleanup instructions to shutdown the application.