3.http-headers

Modify HTTP request and response headers

This use case shows how to modify HTTP headers

cd into the lab directory

cd ~/NGINX-Gateway-Fabric-Lab/labs/3.http-headers

Deploy the sample application

kubectl apply -f 0.app.yaml

Verify that all pods are in the Running state

kubectl get all

Output should be similar to

NAME                           READY   STATUS    RESTARTS   AGE
pod/headers-67f468496f-ncf8s   1/1     Running   0          18s

NAME                 TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)   AGE
service/headers      ClusterIP   10.105.244.169   <none>        80/TCP    18s
service/kubernetes   ClusterIP   10.96.0.1        <none>        443/TCP   268d

NAME                      READY   UP-TO-DATE   AVAILABLE   AGE
deployment.apps/headers   1/1     1            1           18s

NAME                                 DESIRED   CURRENT   READY   AGE
replicaset.apps/headers-67f468496f   1         1         1       18s

Create the gateway object. This deploys the NGINX Gateway Fabric dataplane pod in the current namespace

kubectl apply -f 1.gateway.yaml

Check the NGINX Gateway Fabric dataplane pod status

kubectl get pods

gateway-nginx-c9bcdf4d4-j9pw5 pod is the NGINX Gateway Fabric dataplane

NAME                            READY   STATUS    RESTARTS   AGE
gateway-nginx-c9bcdf4d4-j9pw5   1/1     Running   0          49s
headers-67f468496f-ncf8s        1/1     Running   0          92s

Check the gateway

kubectl get gateway

Output should be similar to

NAME      CLASS   ADDRESS      PROGRAMMED   AGE
gateway   nginx   10.99.25.2   True         4s

Check the NGINX Gateway Fabric Service

kubectl get service

gateway-nginx is the NGINX Gateway Fabric dataplane service

NAME            TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)        AGE
gateway-nginx   NodePort    10.99.25.2       <none>        80:30344/TCP   4m19s
headers         ClusterIP   10.105.244.169   <none>        80/TCP         5m2s
kubernetes      ClusterIP   10.96.0.1        <none>        443/TCP        268d

Create the HTTP routes

kubectl apply -f 2.httproute.yaml

Check the HTTP routes

kubectl get httproute

Output should be similar to

NAME      HOSTNAMES              AGE
headers   ["echo.example.com"]   3s

Get NGINX Gateway Fabric dataplane instance IP and HTTP port

export NGF_IP=`kubectl get pod -l app.kubernetes.io/instance=ngf -o json|jq '.items[0].status.hostIP' -r`
export HTTP_PORT=`kubectl get svc gateway-nginx -o jsonpath='{.spec.ports[0].nodePort}'`

Check NGINX Gateway Fabric dataplane instance IP and HTTP port

echo -e "NGF address: $NGF_IP\nHTTP port  : $HTTP_PORT"

Access the test application

curl -i --resolve echo.example.com:$HTTP_PORT:$NGF_IP http://echo.example.com:$HTTP_PORT/nofilter -H "My-Cool-Header:my-client-value" -H "My-Overwrite-Header:dont-see-this" 

Output should be similar to

HTTP/1.1 200 OK
Server: nginx
Date: Thu, 18 Sep 2025 21:42:45 GMT
Content-Type: text/plain
Content-Length: 450
Connection: keep-alive

Headers:
  header 'Host' is 'echo.example.com:30177'
  header 'X-Forwarded-For' is '10.1.1.8'
  header 'X-Real-IP' is '10.1.1.8'
  header 'X-Forwarded-Proto' is 'http'
  header 'X-Forwarded-Host' is 'echo.example.com'
  header 'X-Forwarded-Port' is '80'
  header 'Connection' is 'close'
  header 'User-Agent' is 'curl/7.81.0'
  header 'Accept' is '*/*'
  header 'My-Cool-Header' is 'my-client-value'
  header 'My-Overwrite-Header' is 'dont-see-this'

Request headers of note:

• User-Agent header is present.
• The header My-Cool-header has its single my-client-value value.
• The header My-Overwrite-Header has its single dont-see-this value.
• Accept-encoding header is not present.

Response Headers X-Header-Set and X-Header-Add are not present.

Access the test application via filters route

curl -i --resolve echo.example.com:$HTTP_PORT:$NGF_IP http://echo.example.com:$HTTP_PORT/headers -H "My-Cool-Header:my-client-value" -H "My-Overwrite-Header:dont-see-this" 

Output should be similar to

HTTP/1.1 200 OK
Server: nginx
Date: Thu, 12 Jun 2025 11:09:02 GMT
Content-Type: text/plain
Content-Length: 495
Connection: keep-alive
X-Header-Add: this-is-the-appended-value
X-Header-Set: overwritten-value

Headers:
  header 'Accept-Encoding' is 'compress'
  header 'My-cool-header' is 'my-client-value,this-is-an-appended-value'
  header 'My-Overwrite-Header' is 'this-is-the-only-value'
  header 'Host' is 'echo.example.com:30344'
  header 'X-Forwarded-For' is '192.168.2.26'
  header 'X-Real-IP' is '192.168.2.26'
  header 'X-Forwarded-Proto' is 'http'
  header 'X-Forwarded-Host' is 'echo.example.com'
  header 'X-Forwarded-Port' is '80'
  header 'Connection' is 'close'
  header 'Accept' is '*/*'

Request headers have been modified:

• User-Agent header is absent.
• The header My-Cool-header gets appended with the new value my-client-value.
• The header My-Overwrite-Header gets overwritten from dont-see-this to this-is-the-only-value.
• The header Accept-encoding remains unchanged as we did not modify it in the curl request sent.

Response headers have been modified:

• Header X-Header-Set set to overwritten-value
• Value this-is-the-appended-value appended to the X-Header-Add header
• X-Header-Remove removed

Delete the lab

kubectl delete -f .