I've been looking for a variable I can use in my dovecot.conf within the INDEX= setting so I can have one index dir per imap server on NFS. I've been looking at http://wiki.dovecot.org/Variables but no variable seems to contain something like server hostname, and I've been hunting for the variable expansion code in dovecot but haven't been able to find it. %l (local IP) won't help me because when using our load balancer, %l is the same IP on all of my servers. %r is close to useful but having a local webmail server on each server means I'd end up with 127.0.0.1 being shared (also I would end up with one directory per unique user/clientIP combo).
Is there a variable that holds the server hostname or something else unique per server, or could one be added, or could someone point me at the code? Thanks.