Alibaba Cloud Service Mesh:Define a routing rule based on traffic labels

Prerequisites

Traffic labels are created. For more information, see Label traffic.

Procedure

1. Create a file named dr-productpage.yaml and copy the following content to the file.

   The following example configures multiple subsets, such as test1, test2, and test3, for productpage:

   apiVersion: networking.istio.io/v1alpha3
   kind: DestinationRule
   metadata:
     name: dr-productpage
   spec:
     host: productpage
     subsets:
     - name: test1
       labels:
         version: test1
     - name: test2
       labels:
         version: test2
     - name: test3
       labels:
         version: test3
     ...
     - name: testn
       labels:
         version: testn
     - name: base
       labels:
         version: base

2. Run the following command to create a destination rule:

   kubectl apply -f dr-productpage.yaml

3. Create a file named vs-productpage.yaml and copy the following content to the file.

   A combination of match.headers and route.destination.subset indicates that traffic with the label is routed to the corresponding destination workload. In the following example, requests with the asm-labels-test label name and the test1 label value are routed to the test1 subset, those with the test2 label value are routed to the test2 subset, and those with the test3 label value are routed to the test3 subset:

   apiVersion: networking.istio.io/v1alpha3
   kind: VirtualService
   metadata:
     name: vs-productpage
   spec:
     hosts:
       - productpage
     http:
     - match:
       - headers:
           asm-labels-test:
            exact: test1
       route:
       - destination:
           host: productpage
           subset: test1
     - match:
       - headers:
           asm-labels-test:
            exact: test2
       route:
       - destination:
           host: productpage
           subset: test2
     - match:
       - headers:
           asm-labels-test:
            exact: test3
       route:
       - destination:
           host: productpage
           subset: test3
     - route:
       - destination:
           host: productpage
           subset: base

   Parameter	Description
   match.headers.asm-labels-test	The name of the traffic label.
   match.headers.exact	The value of the traffic label.
   route.destination.subset	The subset to which the destination workload of the route belongs.

4. Run the following command to create a virtual service:

   kubectl apply -f vs-productpage.yaml

Related operations

Simplify the definition of a virtual service

If workloads of multiple versions exist, the configuration of the virtual service becomes complicated. You can use the following code to simplify the definition of the virtual service and shift traffic to workloads of other versions of the destination workload that is unavailable:

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: vs-productpage
spec:
  hosts:
    - productpage
  http:
  - route:
    - destination:
        host: productpage
        subset: $asm-labels-test
                

Extend the definition of a virtual service and shift traffic between service versions

When the destination service is unavailable, a Service Mesh (ASM) instance of Enterprise Edition allows you to shift traffic to a backup service. The fallback parameter under route specifies the backup service to which requests fall back when the destination service of the label-based route is unavailable. For example, the destination service is not defined or the corresponding pod does not exist. Sample YAML code:

apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
  name: vs-productpage
spec:
  hosts:
    - productpage
  http:
  - route:
    - destination:
        host: productpage
        subset: $asm-labels-test
      fallback:
        target:
          host: productpage
          subset: base