Traefik Reverse Proxy to external Server - reverse-proxy

Question

I would like to access a Keycloak server that is on the internet and not on my docker network. I want to hide the domain of the Keycloak server behind my own domain. So if I go to http://localhost/auth/ then the page from the Keycloak server should be displayed. I don't want to have a redirect to the actual Keycloak server.
I have tried the following configuration but it does not work. When I go to http://localhost/auth I get a "404 page not found". I hope you can help me. Thank you very much for your help :)
docker-compose.yml
version: "3.7"
services:
proxy:
image: traefik:v2.2
command:
- "--api.insecure=true"
- "--providers.docker=true"
- "--providers.docker.exposedbydefault=false"
- "--providers.file=true"
- "--providers.file.filename=/etc/traefik/rules.yml"
- "--entrypoints.web.address=:80"
ports:
- 80:80
volumes:
- /var/run/docker.sock:/var/run/docker.sock
- ./rules.yml:/etc/traefik/rules.yml
website:
image: containous/whoami
labels:
- "traefik.enable=true"
- "traefik.http.routers.website.rule=Host(`localhost`)"
- "traefik.http.routers.website.entrypoints=web"
rules.yml
http:
routers:
my-route:
rule: "Host(`localhost`) && PathPrefix(`/auth`)"
service: my-keycloak-server
services:
my-keycloak-server:
loadBalancer:
servers:
- url: "https://keycloak.domain.com/auth"

Answer 1

Change:
- ./rules.yml:/etc/traefik/rules.yml
to:
- /etc/traefik/rules.yml:/etc/traefik/rules.yml
That should do it!
P.S.
Thanks for the question; really enjoyed learning about Traefik and Keycloak!