Foswiki’s LDAPContrib module does not support configuring multiple LDAP servers for redundancy or resiliency purposes. I’m not talking about consuming multiple difference LDAP stores but rather having the ability to configure a primary and backup(s) LDAP server.

I created a patch to enable this in a rudimentary fashion. It is available on GitHub https://github.com/mike2038/LdapContrib/commit/9260ce093b73f09bd6bfefc1d8b455ee1c4e5c02?diff=unified

This relies on the Net::LDAP module’s behaviour when an array is passed to the host entry for new LDAP connections. This is a preference order based array of ldap:// or ldaps:// URIs, host:port pairs or hostnames.

A couple of points to note about this patch

• No caching of the most recently used LDAP server. For example, in a list of three LDAP servers where the first two are unavailable connection attempts will still be made to them before the third is tried. This will likely cause delays during login or other activities which require working LDAP connections. In my opinion, these delays are preferable to users being unable to login at all.
• If you need different ports or connection schemes (i.e. ldap vs ldaps) or different Root CA certs then results might be mixed. Assuming you have certificates issued by the same Root CA then Net::LDAP seems to work with different hosts and ports. I suggest testing be carried out.