Issue
I installed Docker Engine on Linux Mint Una using this official guide. Everything seems OK. Later when I try to update I get errors:
W: "stable / source / Sources" file acquisition skipped as the repository "https://download.docker.com/linux/ubuntu focal InRelease" does not seem to provide this file (wrong sources.list entry?)
E: The "https://download.docker.com/linux/ubuntu una Release" repository does not have a Release file.
PS: Don't move me the question to Ubuntu, because they will say it's not Ubuntu (even though Linux Mint is based on Ubuntu) and they will remove it. Thank you
How to solve? Thank you
Solution
I had the same problem. On Linux Mint 20.X, you can't install docker using the repository. Instead, install it from .deb packages by following instructions in this paragraph of the official documentation.
Basically you'll need to download 3 .deb files: containerd.io, docker-ce-cli and docker-ce. There are multiple versions, so pick the latest ones (make sure you get all 3 from the same day, or you can experienced some issues later on).
Then install with dpkg -i {deb file} (per official instruction), first containerd.io, then docker-ce-cli and finally docker-ce (there are dependencies and it'll complain if you try installing in the wrong order).
Then be sure to follow the post-installation instructions
EDIT: Ignore everything above!! installing from packages leads to another issue after installing docker compose with apt-get install docker-compose.
Welcome to the wonderful linux world. It's a hell of a mess. Nothing works, but hey, it's free!
The official docker installation documentation for Ubuntu tells you about three paths: install from repository, install from package and install using convenience script.
The first path does NOT work on Linux Mint 20.X, because $(lsb_release -cs) returns una (Mint 20.3) uma (20.2), ulyssa (20.1) or ulyana (20.0) and none of these appear to be working with the package repository mentioned in the official docker documentation. You can quickly find out following the instructions in the doc and running sudo apt update.
A normal person then tries the second path. They download packages manually and install them with dpkg -i, per documentation. I did that and it worked, but after installing docker-compose with sudo apt install docker-compose everything blew up. I wasted a lot of time figuring out what was going on.
It turns out this command sudo apt install docker-compose installs EVERYTHIG you need. It installs docker-ce, docker-ce-cli and containerd.io packages plus, of course, docker-compose. If you have previous versions (installed manually with dpkg -i they collide, docker.service gets masked)
It turns out those packages ARE in official ubuntu repository, so all those 3 installation paths in the official documentation don't make any sense. The correct way to install everything is to run sudo apt install docker-compose
Answered By - PawelRoman Answer Checked By - Willingham (WPSolving Volunteer)