This is what you should do. someone correct me if I'm wrong.
## If you looking for stable release then use following, otherwise you can checkout specific tag also like 14.x.x
## Example to build multiple images or specific.
$ kolla-build --registry
10.10.1.100:4000 -b ubuntu -t source -T 16 --tag zed fluentd kolla-toolbox cron chrony memcached mariadb rabbitmq dnsmasq keepalived haproxy
## If you want to customize image do following, Create template-overrides.j2 file and add following (In my example its horizon)
{% extends parent_template %}
# Horizon
{% block horizon_ubuntu_source_setup %}
RUN apt update -y
RUN apt install -y net-tools vim
RUN touch /root/foobar.txt
{% endblock %}
## Run to build a custom horizon image.
$ kolla-build --registry
10.10.1.100:4000 -b ubuntu -t source --tag zed-1 --template-override template-overrides.j2 horizon