Comment 2 for bug 2003811

Hey Swogat,

We only download images that are used in the roles during the container image prepare step. So the DCN role isn't one of the defaults, we never would have downloaded the etcd container to the undercloud. In the case of etcd, we only download the image if there is a role using the OS::TripleO::Services:Etcd service:
https://github.com/openstack/tripleo-common/blob/master/container-images/tripleo_containers.yaml.j2#L218-L224

You can pass the `--roles-file` argument to the container image prepare command and specify the roles_data.yaml you're using for dcn:

`openstack tripleo container image prepare -e containers-prepare-parameter.yaml --roles-file roles_data.yaml`

https://github.com/openstack/python-tripleoclient/blob/master/tripleoclient/v1/container_image.py#L515-L523