Use extractors for headers

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 link

1. Follow the Get started guide to install Gloo Gateway, set up a gateway resource, and deploy the httpbin sample app.

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 link

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 link

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

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