Currently, the frontend flask application is responsible for running pungi directly. We should change this and split it out into a separate backend process.

It's "ok" to do this using only the database as a medium between frontend and backend. Also, using fedmsg, or celery, or whatever else is okay too... those things just increase the operational/deployment complexity. DB as a medium is probably simplest.

We need this for multiple reasons:

• Permissions - the frontend shouldn't have to run privileged so that it can do composes itself.
• Resources - if the pungi task grows, it could exhaust resources on the frontend and crash the webapp.
• There are scaling oddities. We might want two webapp nodes for load balancing, but .. do they both run composes? which ones where? Separate the compose execution out a separate backend process to make the question moot.