Response Override

Response Override allows you to override the response from the backend with a custom one. This can be useful for scenarios such as returning a custom 404 page when the requested resource is not found or a custom 500 error message when the backend is failing.

Installation

Follow the steps from the Quickstart to install Envoy Gateway and the example manifest. Before proceeding, you should be able to query the example backend using HTTP.

Testing Response Override

cat <<EOF | kubectl apply -f -
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: BackendTrafficPolicy
metadata:
  name: response-override
spec:
  targetRef:
    group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: backend
  responseOverride:
    - match:
        statusCodes:
          - type: Value
            value: 404
      response:
        contentType: text/plain
        body:
          type: Inline
          inline: "Oops! Your request is not found."
    - match:
        statusCodes:
          - type: Value
            value: 500
          - type: Range
            range:
              start: 501
              end: 511
      response:
        contentType: application/json
        body:
          type: ValueRef
          valueRef:
            group: ""
            kind: ConfigMap
            name: response-override-config
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: response-override-config
data:
  response.body: '{"error": "Internal Server Error"}'
EOF

Save and apply the following resource to your cluster:

---
apiVersion: gateway.envoyproxy.io/v1alpha1
kind: BackendTrafficPolicy
metadata:
  name: response-override
spec:
  targetRef:
    group: gateway.networking.k8s.io
    kind: HTTPRoute
    name: backend
  responseOverride:
    - match:
        statusCodes:
          - type: Value
            value: 404
      response:
        contentType: text/plain
        body:
          type: Inline
          inline: "Oops! Your request is not found."
    - match:
        statusCodes:
          - type: Value
            value: 500
          - type: Range
            range:
              start: 501
              end: 511
      response:
        contentType: application/json
        body:
          type: ValueRef
          valueRef:
            group: ""
            kind: ConfigMap
            name: response-override-config
---
apiVersion: v1
kind: ConfigMap
metadata:
  name: response-override-config
data:
  response.body: '{"error": "Internal Server Error"}'
curl --verbose --header "Host: www.example.com" http://$GATEWAY_HOST/status/404
*   Trying 127.0.0.1:80...
* Connected to 172.18.0.200 (172.18.0.200) port 80
> GET /status/404 HTTP/1.1
> Host: www.example.com
> User-Agent: curl/8.5.0
> Accept: */*
>
< HTTP/1.1 404 Not Found
< content-type: text/plain
< content-length: 32
< date: Thu, 07 Nov 2024 09:22:29 GMT
<
* Connection #0 to host 172.18.0.200 left intact
Oops! Your request is not found.
curl --verbose --header "Host: www.example.com" http://$GATEWAY_HOST/status/500
*   Trying 127.0.0.1:80...
* Connected to 172.18.0.200 (172.18.0.200) port 80
> GET /status/500 HTTP/1.1
> Host: www.example.com
> User-Agent: curl/8.5.0
> Accept: */*
>
< HTTP/1.1 500 Internal Server Error
< content-type: application/json
< content-length: 34
< date: Thu, 07 Nov 2024 09:23:02 GMT
<
* Connection #0 to host 172.18.0.200 left intact
{"error": "Internal Server Error"}

Last modified December 6, 2024: feat: add body to ext auth (#4671) (ac86045)