Istio - Configuring Request Routing

TIP

Screencast: https://asciinema.org/a/229605?t=427 (opens new window)

https://istio.io/docs/tasks/traffic-management/request-routing/ (opens new window)

This task shows you how to route requests dynamically to multiple versions of a microservice.

Apply a virtual service

Apply the virtual services which will route all traffic to v1 of each microservice:

kubectl apply -f samples/bookinfo/networking/virtual-service-all-v1.yaml

Display the defined routes:

kubectl get virtualservices -o yaml

Output:

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

Open the Bookinfo site in your browser http://$GATEWAY_URL/productpage and notice that the reviews part of the page displays with no rating stars, no matter how many times you refresh.

---

Route based on user identity

https://istio.io/docs/tasks/traffic-management/request-routing/#route-based-on-user-identity (opens new window)

All traffic from a user named jason will be routed to the service reviews:v2 by forwarding HTTP requests with custom end-user header to the appropriate reviews service.

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

Output:

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

On the /productpage of the Bookinfo app, log in as user jason and refresh the browser. The black star ratings appear next to each review.

Log in as another user (pick any name you wish) and refresh the browser. Now the stars are gone. This is because traffic is routed to reviews:v1 for all users except Jason.

---

You can do the same with user-agent header or URI for example:

  ...
  http:
    - match:
      - headers:
        user-agent:
          regex: '.*Firefox.*'
  ...
  http:
    - match:
      - uri:
        prefix: /api/v1
  ...