Do this in your python virtual env
pip install diskimage-builder
git clone https://github.com/openstack/octavia.git
cd octavia/diskimage-create/
./diskimage-create.sh -b haproxy -a amd64 -o amphora-x64-haproxy -t qcow2 -s 3 -i centos
openstack image create --tag amphora --container-format bare --disk-format qcow2 --file amphora-x64-haproxy.qcow2 Amphora-CentOS7-x64-Haproxy
#Or update an existing image with the tag
glance image-tag-update e4af2c6c-f7fd-4b45-a512-145282236044 amphora