How do I redirect a www url to a no-www url using nginx-ingress-controller? - redirect

Question

I am trying to get the url www.example.com to redirect itself to example.com while preserving everything about the original request in k8s 1.11.1
I am attempting to do this using a simple Ingress, and am then using annotations to redirect it.
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
annotations:
kubernetes.io/tls-acme: "true"
kubernetes.io/ingress.class: "nginx"
nginx.ingress.kubernetes.io/permanent-redirect: https://example.com
nginx.ingress.kubernetes.io/ssl-redirect: "True"
name: example-redirect
spec:
tls:
- hosts:
- www.example.com
secretName: example-tls
rules:
- host: www.example.com
http:
paths:
- backend:
serviceName: example
servicePort: http
The issue here is that I don't want to have any rules/backend. I simply want to redirect www.example.com to example.com using an Ingress, but k8s Ingresses require me to have rules. Are there any workarounds here?

Answer 1

Actually, Ingress resource has strongly defined prerequisites for the relevant API specification. You may exclude rules: field from the general configuration, however backend: should be definitely specified, in the way that Nginx Ingress controller could route network traffic to the target endpoint in case no rules declared or matched.
Whenever you create any specific settings for Nginx Ingress controller either via Annotations or ConfigMaps, both of the options doing the same job of applying some specific configuration to the underlying nginx.conf file which resides on nginx-ingress-controller Pod. It means that Ingress controller applies server {} and location {} blocks into the corresponded Nginx web server Pod for particular host:
server {
server_name www.example.com ;
listen 80;
listen [::]:80;
set $proxy_upstream_name "-";
listen 443 ssl http2;
listen [::]:443 ssl http2;
.............
location / {
set $namespace "default";
set $ingress_name "example-redirect";
set $service_name "example";
set $service_port "http";
set $location_path "/";
......................
}
}
Therefore, I suppose that you can capture nginx.conf file, based on Ingress resource configuration and then apply it independently inside Ingress controller Pod.
I assume that you may consider also to use nginx.ingress.kubernetes.io/from-to-www-redirect: "true" annotation in order to achieve the goal in current scenario.

Answer 2

Following should do:
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
annotations:
kubernetes.io/tls-acme: "true"
kubernetes.io/ingress.class: "nginx"
nginx.ingress.kubernetes.io/configuration-snippet: |
if ($host = 'www.example.com' ) {
rewrite ^ https://example.com$request_uri permanent;
}
name: example-redirect
spec:
tls:
- hosts:
- www.example.com
secretName: example-tls
rules:
- host: www.example.com
http:
paths:
- backend:
serviceName: example
servicePort: http