Extract 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.

2. Follow the Sample app guide to create a gateway proxy with an HTTP listener and deploy the httpbin sample app.

3. 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 GlooTrafficPolicy with 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: gloo.solo.io/v1alpha1
   kind: GlooTrafficPolicy
   metadata:
     name: transformation
     namespace: httpbin
   spec:
     targetRefs:
     - group: gateway.networking.k8s.io
       kind: HTTPRoute
       name: httpbin
     glooTransformation:
       stages:
         early:
           requests:
           - transformation:
               template:
                 extractors:
                   account_id:
                     header: account
                     regex: '(\w+)'
                     subgroup: 1
                 headers:
                   x-account-solo: "account: {{ account_id }}-solo"
   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 glootrafficpolicy transformation -n httpbin