augopkgtest-cloud worker script uses deprecated apt-key tool

[Paride Legovini]

See:

https://git.launchpad.net/autopkgtest-cloud/tree/charms/focal/autopkgtest-cloud-worker/autopkgtest-cloud/worker/worker?id=92bb0adb7a6d8c6237d7f7d5d1b792c2213f044c#n643

From the apt-key(8) manpage:

  apt-key(8) will last be available in Debian 11 and Ubuntu 22.04.

As of today the tool is still present in Kinetic, but we have to move away from it.

[Brian Murray (brian-murray)]

We'll need to see in what releases the replacement tool is supported as we still need to run xenial autopkgtests.

[Paride Legovini (paride)]

Dropping keys in /etc/apt/trusted.gpg.d is supported already in Xenial, however the DEPRECATION section in apt-key(8) says that:

  The binary OpenPGP format works for all apt versions,
  while the ASCII armored format works for apt version >= 1.4.

Xenial has apt 1.2.35 (xenial-updates), so we have to stick to the binary format if we want to cover all the releases. This *should* work:

wget -qO- "https://keyserver.ubuntu.com/pks/lookup?op=get&search=FINGERPRINT" | gpg --dearmor > /etc/apt/trusted.gpg.d/fooppa.gpg