Download for Debian should use `gnupg` instead of `apt-key`

[julianfortune]

Steps

1. docker run -it debian
2. (inside container)
   apt update && apt install -y curl
3. Run the install instruction for Linux (Deb), specifically the line for establishing the GPG key (again inside the container):
   curl -sL "https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x2EE0EA64E40A89B84B2DF73499E82A75642AC823" | apt-key add

Problem

This produces the warning:

Warning: apt-key is deprecated. Manage keyring files in trusted.gpg.d instead (see apt-key(8)).

From the man page:

Use of apt-key is deprecated, except for the use of apt-key del in maintainer scripts to remove existing keys from the main keyring. If such usage of apt-key is desired the additional installation of the GNU Privacy Guard suite (packaged in gnupg) is required.

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

Solution

Instead, we can use gnupg

mkdir -p /etc/apt/keyrings
curl -sL "https://keyserver.ubuntu.com/pks/lookup?op=get&search=0x2EE0EA64E40A89B84B2DF73499E82A75642AC823" | gpg --dearmor -o /etc/apt/keyrings/sbt.gpg
echo "deb [signed-by=/etc/apt/keyrings/sbt.gpg] https://repo.scala-sbt.org/scalasbt/debian all main" | sudo tee /etc/apt/sources.list.d/sbt.list
echo "deb [signed-by=/etc/apt/keyrings/sbt.gpg] https://repo.scala-sbt.org/scalasbt/debian /" | sudo tee /etc/apt/sources.list.d/sbt_old.list

Note the signed-by additions on the last two lines