infra/playbooks/roles/mail/templates/oauth2.inc.php.j2

<?php

$config['oauth_provider'] = 'generic';
$config['oauth_provider_name'] = 'hatecomputers.club <3';
$config['oauth_client_id'] = '{{ roundcube_oauth2_client_id }}';
$config['oauth_client_secret'] = '{{ roundcube_oauth2_client_basic_secret }}';
$config['oauth_auth_uri'] = '{{ roundcube_oauth2_auth_uri }}';
$config['oauth_token_uri'] = '{{ roundcube_oauth2_token_uri }}';
$config['oauth_identity_uri'] = '{{ roundcube_oauth2_user_uri }}';

$config['oauth_verify_peer'] = true;

$config['oauth_scope'] = 'email openid profile';
$config['oauth_identity_fields'] = ['email'];

$config['oauth_login_redirect'] = false;

$config['force_https'] = true;
$config['use_https'] = true;