it would be nice when multiple (redundant) LDAP servers could be configured for the external lookup. Currently, only one server is accepted and when this one fails the lookup fails too.
Implementation should be trivial; just change the configuration format from
| ExtLookupServer "ldap"
| ExtLookupPort 389
| ExtLookupURI "ldap://ldap-1:389 ldaps://ldap-2"
and pass this URI as-is to ldap_initialize(). Rest is done by the LDAP implementation.