For instructions, see ldap.conf
docker run -it --rm alpine /bin/sh -c "apk add openldap-clients;ldapsearch -x -b 'cn=users,dc=in-ulm,dc=de' -H 'ldap://ldap.in-ulm.de'"
append_host_config:
"in-ulm.de":
auth_method: ldap
ldap_servers:
- "ldap.in-ulm.de"
ldap_base: "cn=users,dc=in-ulm,dc=de"