apt-transport-s3-go is a Go port of apt-transport-s3.
# download from https://github.com/winebarrel/apt-transport-s3-go/releases
dpkg -i apt-transport-s3-go_x.x.x_amd64.deb
# aws s3 ls s3://my-bucket/repo/
# PRE dists/
# PRE pool/
echo 'Acquire::s3::region ap-northeast-1;' > /etc/apt/apt.conf.d/s3
echo 'deb s3://my-bucket/repo/ xenial main' > /etc/apt/sources.list.d/s3.list
apt update
apt install any-pkg
export ATS3_LOG_LEVEL=debug
apt update
/usr/lib/apt/methods/s3 s3://my-bucket/key