Custom Errors

This example demonstrates how to use a custom backend to render custom error pages.

Customized default backend

First, create the custom default-backend. It will be used by the Ingress controller later on.

$ kubectl create -f custom-default-backend.yaml
service "nginx-errors" created
deployment.apps "nginx-errors" created

This should have created a Deployment and a Service with the name nginx-errors.

$ kubectl get deploy,svc
NAME                           DESIRED   CURRENT   READY     AGE
deployment.apps/nginx-errors   1         1         1         10s

NAME                   TYPE        CLUSTER-IP  EXTERNAL-IP   PORT(S)   AGE
service/nginx-errors   ClusterIP   10.0.0.12   <none>        80/TCP    10s

Ingress controller configuration

If you do not already have an instance of the nginx Ingress controller running, deploy it according to the deployment guide, then follow these steps:

1. Edit the nginx-ingress-controller Deployment and set the value of the --default-backend flag to the name of the newly created error backend.

2. Edit the nginx-configuration ConfigMap and create the key custom-http-errors with a value of 404,503.

3. Take note of the IP address assigned to the nginx Ingress controller Service.

    $ kubectl get svc ingress-nginx
    NAME            TYPE        CLUSTER-IP  EXTERNAL-IP   PORT(S)          AGE
    ingress-nginx ClusterIP   10.0.0.13   <none>        80/TCP,443/TCP   10m

!!! Note The ingress-nginx Service is of type ClusterIP in this example. This may vary depending on your environment. Make sure you can use the Service to reach nginx before proceeding with the rest of this example.

Testing error pages

Let us send a couple of HTTP requests using cURL and validate everything is working as expected.

A request to the default backend returns a 404 error with a custom message:

$ curl -D- http://10.0.0.13/
HTTP/1.1 404 Not Found
Server: nginx/1.13.12
Date: Tue, 12 Jun 2018 19:11:24 GMT
Content-Type: */*
Transfer-Encoding: chunked
Connection: keep-alive

<span>The page you're looking for could not be found.</span>

A request with a custom Accept header returns the corresponding document type (JSON):

$ curl -D- -H 'Accept: application/json' http://10.0.0.13/
HTTP/1.1 404 Not Found
Server: nginx/1.13.12
Date: Tue, 12 Jun 2018 19:12:36 GMT
Content-Type: application/json
Transfer-Encoding: chunked
Connection: keep-alive
Vary: Accept-Encoding

{ "message": "The page you're looking for could not be found" }

To go further with this example, feel free to deploy your own applications and Ingress objects, and validate that the responses are still in the correct format when a backend returns 503 (eg. if you scale a Deployment down to 0 replica).