I guess the only thing that really matters is the gitlab.rb file?
[root@gitlab ~]# cat /etc/gitlab/gitlab.rb
## THIS CONFIGURATION IS MANAGED BY PUPPET
# for all possible paramters, see:
# https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/files/gitlab-config-template/gitlab.rb.template
## Url on which GitLab will be reachable.
## For more details on configuring external_url see:
## https://gitlab.com/gitlab-org/omnibus-gitlab/blob/629def0a7a26e7c2326566f0758d4a27857b52a3/README.md#configuring-the-external-url-for-gitlab
external_url 'http://gitlab.olindata.vm'
############################################
# Url on which GitLab CI will be reachable #
############################################
## see https://gitlab.com/gitlab-org/omnibus-gitlab/tree/629def0a7a26e7c2326566f0758d4a27857b52a3/doc/gitlab-ci/README.md
ci_external_url 'http://ci.olindata.vm'
#############################################
# Url on which Mattermost will be reachable #
#############################################
## see http://doc.gitlab.com/omnibus/gitlab-mattermost/
mattermost_external_url 'http://chat.olindata.vm'