In this guide, you use an extractor to retrieve the account ID from an account request header by using a regular expression. The extractor is then used to build a custom value for the x-account-solo header. You return the transformed header as a request header.

Before you begin

  2. Get the external address of the gateway and save it in an environment variable.

      export INGRESS_GW_ADDRESS=$(kubectl get svc -n gloo-system gloo-proxy-http -o jsonpath="{.status.loadBalancer.ingress[0]['hostname','ip']}")
echo $INGRESS_GW_ADDRESS  
  
      kubectl port-forward deployment/gloo-proxy-http -n gloo-system 8080:8080

Use extractors for headers

  1. Create a RouteOption or VirtualHostOption resource that defines the following transformation rules:

    • Use a regular expression to capture the value of the account request header and store that value in the account_id extractor.
    • Use the account_id extractor to build a custom string and add this string to the x-account-solo request header.
        kubectl apply -f- <<EOF
apiVersion: gateway.solo.io/v1
kind: RouteOption
metadata:
  name: transformation
  namespace: httpbin
spec:
  targetRefs:
  - group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: httpbin
  options:
    transformations:
      requestTransformation:
        transformationTemplate: 
          parseBodyBehavior: "DontParse"
          extractors:
            account_id:
              header: account
              regex: '(\w+)'
              subgroup: 1
          headers:
            x-account-solo:
              text: "account: {{ account_id }}-solo"
EOF
  
        kubectl apply -n gloo-system -f- <<EOF
apiVersion: gateway.solo.io/v1
kind: VirtualHostOption
metadata:
  name: transformation
  namespace: gloo-system
spec:
  options:
    transformations:
      requestTransformation:
        transformationTemplate:
          parseBodyBehavior: "DontParse"
          extractors:
            account_id:
              header: account
              regex: '(\w+)'
              subgroup: 1
          headers:
            x-account-solo:
              text: "account: {{ account_id }}-solo"
  targetRefs:
  - group: gateway.networking.k8s.io
    kind: Gateway
    name: http
    namespace: gloo-system
EOF

  2. Send a request to the httpbin app with the account: abc123 header. Verify that you see the transformed account value in the x-account-solo request header.

      curl -vik -H "host: www.example.com:8080" \
  -H "Content-Type: application/json" \
  -H "account:abc123" \
  http://$INGRESS_GW_ADDRESS:8080/headers  
  
      curl -vik localhost:8080/headers \
  -H "host: www.example.com" \
  -H "Content-Type: application/json" \
  -H "account:abc123"

    Example output:

       < HTTP/1.1 200 OK
   HTTP/1.1 200 OK
   < access-control-allow-credentials: true
   ...
   < 

   {
     "headers": {
       "Accept": [
        "*/*"
       ],
       "Account": [
         "abc123"
       ],
       "Host": [
         "www.example.com:8080"
       ],
       "X-Account-Solo": [
         "account: abc123-solo"
       ],
       "User-Agent": [
         "curl/8.7.1"
       ],
       "X-Envoy-Expected-Rq-Timeout-Ms": [
         "15000"
       ],
       "X-Forwarded-Proto": [
         "http"
       ],
       "X-Request-Id": [
         "7f2340db-c971-4449-b6cf-3bd8dd377f02"
       ]
     }
   }

Cleanup

You can remove the resources that you created in this guide.

  kubectl delete virtualhostoption transformation -n gloo-system
kubectl delete routeoption transformation -n httpbin