Configuration for Gitea

In Gitea, go to Site Administration > Authentication Sources and click Add Authentication Source Select LDAP (via BindDN)

Host: Your lldap server's ip/hostname
Port: Your lldap server's port (3890 by default)
Bind DN: uid=admin,ou=people,dc=example,dc=com
Bind Password: Your bind user's password
User Search Base: ou=people,dc=example,dc=com
User Filter: In this example only members of the group git_user can log in. To log in they can either use their email address or user name:
(&(memberof=cn=git_user,ou=groups,dc=example,dc=com)(|(uid=%[1]s)(mail=%[1]s)))
For more info on the user filter, see: https://docs.gitea.io/en-us/authentication/#ldap-via-binddn
Admin Filter: Use similar string as above or leave it empty if you don't want LDAP users to be admins.
Username Attribute: uid
Email Attribute: mail
Check Enable User Synchronization

Replace every instance of dc=example,dc=com with your configured domain.

After applying the above settings, users should be able to log in with either their user name or email address.