How to force https for redirect_url parameter with OIDC

[DonDebonair]

I'm trying to setup OIDC with Authelia for Technitium DNS. When I try to login with OpenID Connect, Technitium gives the following error: Error! Failed to reach SSO provider. Please contact your administrator.

The Authelia logs show the following:

Pushed Authorization Request failed with error: The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed. The 'redirect_uri' parameter does not match any of the OAuth 2.0 Client's pre-registered 'redirect_uris'. The 'redirect_uris' registered with OAuth 2.0 Client with id 'technitium-dns' did not match 'redirect_uri' value 'http://dns.mydomain.com/sso/callback'

In Authelia the OIDC client has https://dns.mydomain.com/sso/callback as redirect url.

Both Technitium DNS and Authelia are behind a reverse proxy that providers HTTPS, but Technitium DNS is still using http for the redirect_url parameter. How can I fix this?

[ShreyasZare]

Thanks for asking. You need to configure a few extra headers on your reverse proxy so that the DNS server can figure out the redirect URL correctly. You will find the instructions for that on the same SSO config page regarding the X-Forwarded-Proto and other headers.

[DonDebonair]

Thanks for the quick answer! Are you referring to the Technitium documentation? Can you link the page you're referring to?

edit: nevermind, you're referring to the SSO config page in the Technitium DNS console. Will try to configure my reverse proxy correctly.

[DonDebonair]

I checked my reverse proxy config and X-Forwarded-Proto and X-Forwarded-Host are already correctly set for all upstream backends, where X-Forwarded-Proto is https. So I don't get why Technitium DNS is using http when constructing the redirect url.

[ShreyasZare]

You need to configure the Reverse Proxy Addresses option in Settings > Web Service section for this to work.

[DonDebonair]

Thanks, I managed to get that setting working. Is it possible to set the Reverse Proxy Addresses through an environment variable? I'd like to fully automate the setup of Technitium DNS.

[ShreyasZare]

Good to know you got it working. There is no environment variable for it currently but will get it added in the next update.