/usr/lib/python2.7/dist-packages/charmtools/templates/bash/files/hooks/relation-name-relation-joined is in charm-tools 2.1.2-0ubuntu4.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 | #!/bin/sh
# This must be renamed to the name of the relation. The goal here is to
# affect any change needed by relationships being formed
# This script should be idempotent.
#raw
juju-log $JUJU_REMOTE_UNIT joined
#end raw
|