How to configure header matching - Alibaba Cloud Service Mesh

You can include custom fields in request headers to differentiate requests and perform different handling operations based on these custom fields. This topic describes how to configure header matching.

Prerequisites

The preparations are completed, and the helloworld and sleep services are deployed. For more information, see Preparations.

Procedure

Check whether the service configurations take effect.
1. Use kubectl to connect to the Container Service for Kubernetes (ACK) cluster based on the information in the kubeconfig file, and then run the following command to enable bash for the sleep service:
```
kubectl exec -it deploy/sleep -- sh
```
2. Run the following command to send a request to the helloworld service:
```
curl helloworld:5000/hello
```
  The expected output is that helloworld-v1 or helloworld-v2 randomly responds to the request.
```
Hello version: v2, instance: helloworld-v2-6b96c5684-4****
Hello version: v1, instance: helloworld-v1-6d77f4c4cf-p****
```

Use the following content to configure a destination rule. For more information, see Manage destination rules.

apiVersion: networking.istio.io/v1beta1
kind: DestinationRule
metadata:
  name: helloworld
  namespace: default
spec:
  host: helloworld
  subsets:
    - labels:
        version: v1
      name: v1
    - labels:
        version: v2
      name: v2

Use the following content to create a virtual service and add a header matching configuration. For more information, see Manage virtual services.
The following configuration indicates that the test-header request header is exactly matched. If the value is v1, the request is sent to helloworld-v1. If the value is v2, the request is sent to helloworld-v2.

apiVersion: networking.istio.io/v1beta1
kind: VirtualService
metadata:
  name: helloworld-vs
  namespace: default
spec:
  hosts:
    - helloworld
  http:
    - match:
        - headers:
            test-header:
              exact: v1
      route:
        - destination: 
            host: helloworld
            subset: v1
    - match:
        - headers:
            test-header:
              exact: v2
      route:
        - destination: 
            host: helloworld
            subset: v2

Check whether the configurations take effect.
1. Use kubectl to connect to the ACK cluster based on the information in the kubeconfig file, and then run the following command to enable bash for the sleep service:
```
kubectl exec -it deploy/sleep -- sh
```
2. Run the following command to send a request with the test-header: v1 header to the helloworld service:
```
curl -H "test-header:v1" helloworld:5000/hello
```
  Expected output:
```
Hello version: v1, instance: helloworld-v1-6d77f4c4cf-p****
```
3. Run the following command to send a request with the test-header: v2 header to the helloworld service:
```
curl -H "test-header:v2" helloworld:5000/hello
```
  Expected output:
```
Hello version: v2, instance: helloworld-v2-6b96c5684-4****
```