Oracle LD_LIBRARY_PATH for ruby-oci8/rails
Just putting this somewhere on the internet to hopefully save some other poor bastard the trouble of figuring it out.
To get the oracle instant client libraries to always be found even by background services etc (say monit restarting a mongrel) add a file in /etc/ld.so.conf.d called oracle-client.conf with a single unquoted line that is the path to your oracle instant client install eg /opt/oracle/instantclient_11_1 save it and run ldconfig.
All fixed.