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Istio Example: Request Routing

Bookinfo Application

Tasks > Traffic Management > Request Routing

tags: ITRI, istio, example

Reference

Target

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

Review Bookinfo

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其中 Bookinfo 對 review 部屬了 v1~v3 共三種 version。

# kubectl get pod  -l app=reviews -n istio-example
NAME                          READY   STATUS    RESTARTS   AGE
reviews-v1-5787f7b87-5g6k4    2/2     Running   0          5h9m
reviews-v2-6d8b975647-t9t2m   2/2     Running   0          5h9m
reviews-v3-7d5549f9-sphc8     2/2     Running   0          5h9m

If you refresh the page several times (重新整理頁面多次時), you should see different versions of reviews shown in productpage.

  • This is because without an explicit default service version to route to, Istio routes requests to all available versions in a round robin fashion.
  • Since we haven’t yet used Istio to control the version routing.
  • Then it is presented in a round robin style (no stars, red stars, black stars).

Apply default destination rules

Before using Istio to control the Bookinfo version routing, we need to define the available versions, called subsets, in destination rules.

Create default destination rules for the Bookinfo services.

Since we did not enable mutual TLS,

# kubectl apply -f samples/bookinfo/networking/destination-rule-all.yaml -n istio-example

Display the destination rules.

# kubectl get destinationrules -n istio-example
NAME          HOST          AGE
details       details       1d
productpage   productpage   1d
ratings       ratings       1d
reviews       reviews       1d

Request Routing

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

In this task, we apply rules that route all traffic to v1 (version 1) of the microservices.

Apply a virtual service

To route to one version only, we 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.

Virtual services were applied in samples/bookinfo/networking/virtual-service-all-v1.yaml.





















































apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: productpage
spec:
  hosts:
  - productpage
  http:
  - route:
    - destination:
        host: productpage
        subset: v1
---
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: reviews
spec:
  hosts:
  - reviews
  http:
  - route:
    - destination:
        host: reviews
        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: details
spec:
  hosts:
  - details
  http:
  - route:
    - destination:
        host: details
        subset: v1
---

Apply the virtual services.

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

Check the virtual services.

# kubectl get virtualservice
NAME          GATEWAYS   HOSTS           AGE
details                  [details]       1h
productpage              [productpage]   1h
ratings                  [ratings]       1h
reviews                  [reviews]       1h

Result

Go to the url: http://100.86.1.141/productpage, we would see no stars are on the page again.

Route based on user identity

Target

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 reviews:v2.

How to identify the specific user?

Istio doesn’t have any special, built-in understanding of user identity. This example is enabled by the fact that the productpage service adds a custom end-user header to all outbound HTTP requests to the reviews service.

  • 因此 Istio 實際上並不知道倒底是哪個 user 發出 request。
    • 再將上方說明文字解釋一次：這個例子是 productpage service → review service 的 request 加上 end-user header field 並通過判斷 header 實現的。
  • Reminder that reviews:v2 is the version that includes the star ratings feature.
    Version GUI
    v2
  • Version v2 calls the ratings service, and displays each rating as 1 to 5 black stars.
    		•

Apply a virtual service

Virtual services were applied in samples/bookinfo/networking/virtual-service-reviews-test-v2.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
  • When matching end-user=jason, this request would be routed to reviews:v2.
  • Other requests would be routed to reviews:v1.

Apply the virtual services.

# kubectl apply -f samples/bookinfo/networking/virtual-service-reviews-test-v2.yaml -n istio-example

Result

Open browser to http://$GATEWAY_URL/productpage to view the Bookinfo web page. And sign in jason without any password.

Refresh the browser. We would see the black start as review:v2 there always.

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:v1 for all users except Jason.

Clean Up

Remove the application virtual services.

# kubectl delete -f samples/bookinfo/networking/virtual-service-all-v1.yaml -n istio-example

If we want to clear all the Bookinfo example, use the script.

# samples/bookinfo/platform/kube/cleanup.sh

Confirm shutdown.

# kubectl get virtualservices -n istio-example    #-- there should be no virtual services
# kubectl get destinationrules -n istio-example   #-- there should be no destination rules
# kubectl get gateway -n istio-example            #-- there should be no gateway
# kubectl get pods -n istio-example               #-- the Bookinfo pods should be deleted
** End **
Last changed by 
 
Yihsuan Huang
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