I am using ingress-nginx in my GKE cluster to expose my services. I have 2 different GKE cluster (v1.19.12-gke.2101) that both use ingress-nginx (chart v4.0.6).

On those cluster, I expose some services with a oauth-proxy. It works perfectly on the first cluster, but it doesn't on the second one with a 404 on the path /test/. I have been investigating a long time without finding what could cause this issue. The main difference I have found is in the nginx.conf file where the location differs. Here is the difference :

First cluster (working):

location ~* "^/test(/|$)(.*)/" {

Second cluster (not working):

location /test(/|$)(.*)/ {

Here is the ingress used for this line :

apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  annotations:
    nginx.ingress.kubernetes.io/auth-url: "<auth-url>"
    nginx.ingress.kubernetes.io/auth-signin: "<auth-signin>"
    nginx.ingress.kubernetes.io/auth-realm: 'Authentication Required'
    kubernetes.io/tls-acme: 'true'
    ingress.kubernetes.io/force-ssl-redirect: 'true'
    nginx.ingress.kubernetes.io/proxy-body-size: 500m
    cert-manager.io/cluster-issuer: "letsencrypt-prod-dns01"
  name: service-oauth
  namespace: default
spec:
  rules:
  - host: "test.com"
    http:
      paths:
      - path: "/test(/|$)(.*)"
        pathType: ImplementationSpecific
        backend:
          service:
            name: test
            port:
              number: 1234
  ingressClassName: nginx
  tls:
  - secretName: test-tls
    hosts:
      - "test.com"

I have checked all my configuration files (ingress, services) without finding any differences. If you have any idea where the problem could come from, let me know.

Thanks for your help.