With virt-builder we are trying to persuade Linux distros to start publishing high quality metadata about their cloud and VM images. Then virt-builder will just pull down those images automatically. It's been a very long and slow process. So far we can only support Ubuntu, OpenSuSE and (coming shortly) CentOS.

Even though Red Hat sponsors the project, we've still not managed to get either Fedora or RHEL to publish metadata, after 2+ years of trying. But I believe this method of publishing metadata is the way to make the whole process sustainable long term.

Edit: I should say I didn't read your original posting closely enough. It sounds as if you're looking for fully formed applications (eg. PostgreSQL or whatever) in appliances. Personally I wouldn't use an existing appliance like that for trust reasons (also the reason I'm not over-keen on half-baked Docker repositories), but with virt-builder you can do something like:

    $ virt-builder centos-7.2 --install postgresql-server

I'd like to see a good opinionated base stack for say Django (i.e. Postgres, uwsgi and redis) as well as fully fledged installs for stuff like Sentry, Gitlab, Zulip and similar apps.

We've of course built our own Django deploy using Ansible but I'd like to see some community efforts that are shared and get reviewed, critiqued etc.

The downside is everything then is fragmented depending on the builder you choose (ansible vs whatever).