Wrong Authelia URL in redirection for unauthenticated users

[mathieures]

Hello, I have been trying to set up Authelia for the first time since a few days, with the aim to access it from https://mydomain.tld/auth.

However, I found that the configMap.session.cookies[].path key was not taken into account when filling the values file. I am using a modified version of the values.local.yaml file, with many defaults but the specific key configMap.session.cookies set to:

[...]
configMap:
  session:
    cookies:
      -
        subdomain: ''
        domain: 'mydomain.tld'
        path: 'auth'
[...]

However, I was getting the following error whenever trying to access an application behind a Traefik v2 reverse proxy (the default with k3s):

time="2024-08-04T22:12:01Z" level=info msg="Access to https://mydomain.tld/myapplication/index.html (method GET) is not authorized to user <anonymous>, responding with status code 302 with location redirect to https://mydomain.tld/?rd=https%3A%2F%2Fmydomain.tld%2Fmyapplication%2Findex.html&rm=GET" method=GET path=/api/authz/forward-auth remote_ip=10.42.0.1

Notice the redirection URL being https://mydomain.tld/?rd=..., not taking into account the auth subpath that should be there.

Fortunately, I have solved the problem by manually editing the configuration.yaml ConfigMap to add the missing subpath to the session.cookies[].authelia_url key, going from the original:

[...]
    session:
      name: 'authelia_session'
      same_site: 'lax'
      inactivity: '5 minutes'
      expiration: '1 hour'
      remember_me: '1 month'
      cookies:
        - domain: 'mydomain.tld'
          authelia_url: 'https://mydomain.tld'
[...]

To the working:

[...]
    session:
      name: 'authelia_session'
      same_site: 'lax'
      inactivity: '5 minutes'
      expiration: '1 hour'
      remember_me: '1 month'
      cookies:
        - domain: 'mydomain.tld'
          authelia_url: 'https://mydomain.tld/auth' # added '/auth' here
[...]

I have no knowledge in writing Helm charts so I couldn't make a pull request, but I believe this line is to blame:

chartrepo/charts/authelia/templates/configMap.yaml

Line 205 in 7c554d6

authelia_url: {{ printf "https://%s" (include "authelia.ingress.host" (merge (dict "SubDomain" $cookie.subdomain "Domain" $cookie.domain) $)) | squote }}

I decided to create this issue because I have seen others getting the same error, so hopefully this can help someone. Even if it’s a configuration issue on my end, I’d be glad to know that it is one. If needed, I can provide the whole values file.

Thank you for your time.