/usr/lib/python2.7/dist-packages/charmtools/templates/bash/files/hooks/install 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 8 9 10 | #!/bin/bash
#
# Here do anything needed to install the service
# i.e. apt-get install -y foo or bzr branch http://myserver/mycode /srv/webroot
#
# Make sure this hook exits cleanly and is idempotent, common problems here are
# failing to account for a debconf question on a dependency, or trying to pull
# from github without installing git first.
apt-get install -y $metadata.package
|