/usr/share/tripleo-image-elements/horizon/element-deps is in python-tripleo-image-elements 0.7.1-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 | apache2
iptables
os-apply-config
os-refresh-config
os-svc-install
source-repositories
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