Repositories configuration
Most of servers may use same repositories set:
deb http://ftp.us.debian.org/debian/ buster main contrib non-free
deb http://ftp.us.debian.org/debian/ buster-updates main
deb http://security.debian.org/ buster/updates main
deb http://pkg.yeti-switch.org/debian/buster 1.11 main
deb http://apt.postgresql.org/pub/repos/apt/ buster-pgdg main
System repositories can be changed by editing of file: /etc/apt/sources.list. Since we use our own package repository you have add our key to trusted.
# wget http://pkg.yeti-switch.org/key.gpg -O - | apt-key add -
PGDG repository key also should be added to trusted list
# wget https://www.postgresql.org/media/keys/ACCC4CF8.asc -O - | apt-key add -