After reading the man-page of apt-key, on CIS Ubuntu Linux 20.04 LTS, I had to do these:
- Added the new key
$ sudo apt-key add /usr/share/keyrings/jenkins-keyring.asc
OK
- List all the existing keys to be sure:
$ apt-key list
/etc/apt/trusted.gpg
--------------------
[...]
pub rsa4096 2023-03-27 [SC] [expires: 2026-03-26]
6366 7EE7 4BBA 1F0A 08A6 9872 5BA3 1D57 EF59 75CA
uid [ unknown] Jenkins Project <jenkinsci-board@googlegroups.com>
sub rsa4096 2023-03-27 [E] [expires: 2026-03-26]
[...]
- Updated the file /etc/apt/sources.list.d/jenkins.list like this:
deb https://pkg.jenkins.io/debian-stable binary/
- Re-run the apt update command:
$ sudo apt update
Hit:1 http://eu-west-1.ec2.archive.ubuntu.com/ubuntu focal InRelease
Hit:2 http://eu-west-1.ec2.archive.ubuntu.com/ubuntu focal-updates InRelease
Hit:3 http://eu-west-1.ec2.archive.ubuntu.com/ubuntu focal-backports InRelease
Ign:4 https://pkg.jenkins.io/debian-stable binary/ InRelease
Hit:5 https://pkg.jenkins.io/debian-stable binary/ Release
Hit:6 http://security.ubuntu.com/ubuntu focal-security InRelease
Reading package lists... Done
Building dependency tree
Reading state information... Done
All packages are up to date.