Pungi consists of multiple separate executables backed by a common library.
The main entry-point is the pungi-koji script. It loads the compose configuration
and kicks off the process. Composing itself is done in phases. Each phase is
responsible for generating some artifacts on disk and updating the compose
object that is threaded through all the phases.
Pungi itself does not actually do that much. Most of the actual work is delegated
to separate executables. Pungi just makes sure that all the commands are invoked
in the appropriate order and with correct arguments. It also moves the artifacts
to correct locations.
