I just moved a drupal website from one server to another. On the original server the site was set up directly in apache. On the new server, i have a docker layer in between:
The machine runs a debian system with docker, and the (currently only) docker container features a debian/apache2/mysql/php setup. The container's ports 80 and 443 are exposed to the outside, and the migrated website works just fine. With one exception:
The migrated drupal website contains an openid_provider module. I used this to login to other sites. However, since the migration this function has broken: On most of the sites i try to login using openid (other drupal sites, wordpress, mediawiki) the login fails. These sites raise messages in the form "OpenID verification failed: Server denied check_authentication".
Fun fact: openid login still works on stackexchange sites ;)
Does anyone have a clue what is going on? There's no (related) errors or warnings in the apache logs - neither on the open_id providing, migrated site, nor in the client logs.
I don't have an idea where and how to start debugging. Let me know, if you need more details.
Here's the drupal module i use: https://www.drupal.org/project/openid_provider (I know, it's deprecated).
Any help would be appreciated.