Unable to use FQDN for Authentik

[drtech981]

I am hosting my authentik server on a different server than my endpoints.
Authentik -> Server A
Uptime-Kuma -> Server B

Authentik is hosted behind NGINX Proxy Manager, with no custom config.

On NPM infront of Uptime-Kuma, everything works if I post the default custom config as generated by Authentik.

However, if I change
proxy_pass https://local.ip:9000/outpost.goauthentik.io;
to
proxy_pass https://authentik.mydomain.cc/outpost.goauthentik.io;

I start getting a Server Error 500.

What should be done in this case?

[ImmanuelVonNeumann]

What type of virtualization are you using? (Docker, Podman, K8S, Bare-Metal)

My first guess would be that NGINX Proxy Manager can't resolve authentik.mydomain.cc.
When using virtualization, the containerization engine likely adds dns routes for your container's name so try replacing authentik.mydomain.cc with your authentik container's name.
The proxy_pass variable is not visible outside your network and thus does not need to be set to your external FQDN.

[drtech981]

I'm using docker, but the application (uptime-kuma) is hosted on a separate physical server (with a different cloud provider) than my authentik container.

I've checked authentik.mydomain.cc is reachable from within the nextcloud container.

[ImmanuelVonNeumann]

I'm using docker, but the application (uptime-kuma) is hosted on a separate physical server (with a different cloud provider) than my authentik container.

I've checked authentik.mydomain.cc is reachable from within the nextcloud container.

Please check if it is reachable from within nginx-proxy-manager and check if it is really the authentik container (by verifying the resolved ip or content using curl)

[drtech981]

Using curl, I'm getting a 301 Moved Permanently

[joetheshmo]

I'm also having this same issue with NPM proxying authentik. If I use the proxy_pass to the host bound ports (9000 or 9443) and update the embedded outpost to also use it, the proxy works using authentik login first. If I use the FQDN in NPM that is proxying authentik (and update the embedded outpost as well), I get 500 errors endlessly. I confirmed I can reach the NPM server proxying authentik (and getting the proper IP from DNS) in the NPM container proxying the app I am trying to protect with authentik. Did you ever figure this out?