HTTP redirects and rewrites

Learn how to redirect or rewrite your HTTP traffic using NGINX Gateway Fabric.

Overview

HTTPRoute filters can be used to configure HTTP redirects or rewrites. Redirects return HTTP 3XX responses to a client, instructing it to retrieve a different resource. Rewrites modify components of a client request (such as hostname and/or path) before proxying it upstream.

Note:
NGINX Gateway Fabric currently does not support path-based redirects.

To see an example of a redirect using scheme and port, see the HTTPS Termination guide.

In this guide, we will be configuring a path URL rewrite.

Before you begin

Install NGINX Gateway Fabric.
Save the public IP address and port of NGINX Gateway Fabric into shell variables:
```
GW_IP=XXX.YYY.ZZZ.III
GW_PORT=<port number>
```

Note:
In a production environment, you should have a DNS record for the external IP address that is exposed, and it should refer to the hostname that the gateway will forward for.

Set up

Create the coffee application in Kubernetes by copying and pasting the following block into your terminal:

kubectl apply -f - <<EOF
apiVersion: apps/v1
kind: Deployment
metadata:
  name: coffee
spec:
  replicas: 1
  selector:
    matchLabels:
      app: coffee
  template:
    metadata:
      labels:
        app: coffee
    spec:
      containers:
      - name: coffee
        image: nginxdemos/nginx-hello:plain-text
        ports:
        - containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: coffee
spec:
  ports:
  - port: 80
    targetPort: 8080
    protocol: TCP
    name: http
  selector:
    app: coffee
EOF

This will create the coffee service and a deployment. Run the following command to verify the resources were created:

kubectl get pods,svc

Your output should include the coffee pod and the coffee service:

NAME                          READY   STATUS      RESTARTS   AGE
pod/coffee-6b8b6d6486-7fc78   1/1     Running   0          40s


NAME                 TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)   AGE
service/coffee       ClusterIP   10.96.189.37   <none>        80/TCP    40s

Configure a path rewrite

To create the cafe gateway, copy and paste the following into your terminal:

kubectl apply -f - <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: Gateway
metadata:
  name: cafe
spec:
  gatewayClassName: nginx
  listeners:
  - name: http
    port: 80
    protocol: HTTP
EOF

The following HTTPRoute defines two filters that will rewrite requests such as the following:

http://cafe.example.com/coffee to http://cafe.example.com/beans
http://cafe.example.com/coffee/flavors to http://cafe.example.com/beans
http://cafe.example.com/latte/prices to http://cafe.example.com/prices

To create the httproute resource, copy and paste the following into your terminal:

kubectl apply -f - <<EOF
apiVersion: gateway.networking.k8s.io/v1
kind: HTTPRoute
metadata:
  name: coffee
spec:
  parentRefs:
  - name: cafe
    sectionName: http
  hostnames:
  - "cafe.example.com"
  rules:
  - matches:
    - path:
        type: PathPrefix
        value: /coffee
    filters:
    - type: URLRewrite
      urlRewrite:
        path:
          type: ReplaceFullPath
          replaceFullPath: /beans
    backendRefs:
    - name: coffee
      port: 80
  - matches:
    - path:
        type: PathPrefix
        value: /latte
    filters:
    - type: URLRewrite
      urlRewrite:
        path:
          type: ReplacePrefixMatch
          replacePrefixMatch: /
    backendRefs:
    - name: coffee
      port: 80
EOF

Send traffic

Using the external IP address and port for NGINX Gateway Fabric, we can send traffic to our coffee application.

Note:
If you have a DNS record allocated for cafe.example.com, you can send the request directly to that hostname, without needing to resolve.

curl --resolve cafe.example.com:$GW_PORT:$GW_IP http://cafe.example.com:$GW_PORT/coffee/flavors

Notice in the output that the URI has been rewritten:

Server address: 10.244.0.6:8080
Server name: coffee-6b8b6d6486-7fc78
...
URI: /beans

Other examples:

curl --resolve cafe.example.com:$GW_PORT:$GW_IP http://cafe.example.com:$GW_PORT/coffee

Server address: 10.244.0.6:8080
Server name: coffee-6b8b6d6486-7fc78
...
URI: /beans

curl --resolve cafe.example.com:$GW_PORT:$GW_IP http://cafe.example.com:$GW_PORT/latte/prices

Server address: 10.244.0.6:8080
Server name: coffee-6b8b6d6486-7fc78
...
URI: /prices