Configuring Request Routing

This task shows you how to configure dynamic request routing based on weights and HTTP headers.

Before you begin

Note: This task assumes you are deploying the application on Kubernetes. All of the example commands are using the Kubernetes version of the rule yaml files (e.g., samples/bookinfo/kube/route-rule-all-v1.yaml). If you are running this task in a different environment, change kube to the directory that corresponds to your runtime (e.g., samples/bookinfo/consul/route-rule-all-v1.yaml for the Consul-based runtime).

Content-based routing

Because the BookInfo sample deploys 3 versions of the reviews microservice, we need to set a default route. Otherwise if you access the application several times, you’ll notice that sometimes the output contains star ratings. This is because without an explicit default version set, Istio will route requests to all available versions of a service in a random fashion.

Note: This task assumes you don’t have any routes set yet. If you’ve already created conflicting route rules for the sample, you’ll need to use replace rather than create in one or both of the following commands.

  1. Set the default version for all microservices to v1.

    istioctl create -f samples/bookinfo/kube/route-rule-all-v1.yaml

    Note: In a Kubernetes deployment of Istio, you can replace istioctl with kubectl in the above, and for all other CLI commands. Note, however, that kubectl currently does not provide input validation.

    You can display the routes that are defined with the following command:

    istioctl get routerules -o yaml

    apiVersion: config.istio.io/v1alpha2
kind: RouteRule
metadata:
  name: details-default
  namespace: default
  ...
spec:
  destination:
    name: details
  precedence: 1
  route:
  - labels:
      version: v1
---
apiVersion: config.istio.io/v1alpha2
kind: RouteRule
metadata:
  name: productpage-default
  namespace: default
  ...
spec:
  destination:
    name: productpage
  precedence: 1
  route:
  - labels:
      version: v1
---
apiVersion: config.istio.io/v1alpha2
kind: RouteRule
metadata:
  name: ratings-default
  namespace: default
  ...
spec:
  destination:
    name: ratings
  precedence: 1
  route:
  - labels:
      version: v1
---
apiVersion: config.istio.io/v1alpha2
kind: RouteRule
metadata:
  name: reviews-default
  namespace: default
  ...
spec:
  destination:
    name: reviews
  precedence: 1
  route:
  - labels:
      version: v1
---

    Since rule propagation to the proxies is asynchronous, you should wait a few seconds for the rules to propagate to all pods before attempting to access the application.

  2. Open the BookInfo URL (http://$GATEWAY_URL/productpage) in your browser

    You should see the BookInfo application productpage displayed. Notice that the productpage is displayed with no rating stars since reviews:v1 does not access the ratings service.

  3. Route a specific user to reviews:v2

    Lets enable the ratings service for test user “jason” by routing productpage traffic to reviews:v2 instances.

    istioctl create -f samples/bookinfo/kube/route-rule-reviews-test-v2.yaml

    Confirm the rule is created:

    istioctl get routerule reviews-test-v2 -o yaml

    apiVersion: config.istio.io/v1alpha2
kind: RouteRule
metadata:
  name: reviews-test-v2
  namespace: default
  ...
spec:
  destination:
    name: reviews
  match:
    request:
      headers:
        cookie:
          regex: ^(.*?;)?(user=jason)(;.*)?$
  precedence: 2
  route:
  - labels:
      version: v2

  4. Log in as user “jason” at the productpage web page.

    You should now see ratings (1-5 stars) next to each review. Notice that if you log in as any other user, you will continue to see reviews:v1.

Understanding what happened

In this task, you used Istio to send 100% of the traffic to the v1 version of each of the BookInfo services. You then set a rule to selectively send traffic to version v2 of the reviews service based on a header (i.e., a user cookie) in a request.

Once the v2 version has been tested to our satisfaction, we could use Istio to send traffic from all users to v2, optionally in a gradual fashion. We’ll explore this in a separate task.

Cleanup

  • Remove the application routing rules.

    istioctl delete -f samples/bookinfo/kube/route-rule-all-v1.yaml
istioctl delete -f samples/bookinfo/kube/route-rule-reviews-test-v2.yaml

  • If you are not planning to explore any follow-on tasks, refer to the BookInfo cleanup instructions to shutdown the application.

Further reading