apt/apt-get
commands may use SRV record to find nearby APT service. [1]
However, offical Debian/Ubuntu images cannot utilize such functonality unless /etc/services
file is present.
This means APT will download packages from deb.debian.org
/ archive.ubuntu.com
as usual. 🤣
This also means local APT (cache/proxy) servers is bypassed and the build process may be slowed down if the bandwidth is limited.
Workaround