The Debian Archive Software consisting of dak (Debian Archive Kit) for the archive and the buildd related parts wanna-build/sbuild.
dak is the collection of programs (scripts) used to maintain the Debian project archive. You need a running postgresql
Logs of Dak activity are also available in /srv/ftp-master.debian.org/log/current there as well.
Dak is part of a larger ecosystem of multiple pieces of software interacting to make the FTP archive works.
The above graphic is generated from a dot file which is maintained in CollabMaint:
See also the releases workflow.