CiviLDAP provides LDAP authentication for Gitlab based on civicrm.org logins. In the past, it also provided LDAP authentication to JIRA and Confluence.
The service runs on
Gitlab issues should be tagged with ldap (although it also includes the ssh LDAP service, which is a separate service running off OpenLDAP).
More documentation: https://lab.civicrm.org/infrastructure/ops/blob/master/ldap-websites.md