Introduction

Installing Docker on Linux should be straightforward, but the official documentation often fragments the process into separate pages for Debian and Ubuntu. In reality, these operating systems belong to the same family, and their installation processes are nearly identical.

Whether you are running the latest Ubuntu 24.04 LTS, Debian 13 (Trixie), or a derivative distribution like Kali Linux, ParrotSec, or Linux Mint, the logic remains the same.

This guide provides a unified, "evergreen" method to install Docker Engine using the modern DEB822 source format. This approach is cleaner, safer, and future-proof for modern apt-based systems.

Step 1: Prepare the system

First, we need to ensure the package index is updated and install the necessary dependencies to allow apt to use repositories over HTTPS.

Update the package index and install dependencies:

Step 2: Define your distribution base

This is the only step where you need to make a choice. Docker repositories are organized by the "upstream" distribution.

• Choose debian if you use: Debian, Kali Linux, ParrotSec, Raspbian.
• Choose ubuntu if you use: Ubuntu, Linux Mint, Pop!_OS, Zorin OS.

Export the variable to make subsequent commands universal for your session:

Step 3: Add Docker’s official GPG key

Now we will create a dedicated directory for the keyrings. Unlike the old method of putting keys in /etc/apt/trusted.gpg, putting them in a dedicated directory is safer.

Create the directory with the correct permissions:

Download the official Docker GPG key. By using the $DOCKER_DISTRO variable, this command automatically fetches the correct key for your system:

Ensure the GPG key file is readable by all users. This is necessary because the apt package manager runs as a non-privileged user (_apt) and requires read access to verify signatures:

Step 4: Configure the repository (DEB822 style)

We will add the repository using the modern DEB822 format. This is superior to the old one-line sources.list format because it is structured and easier to parse.

Note for Derivative Distros: The command below uses $(... echo ...) magic to automatically detect your release codename (like bookworm or noble). It is designed to work on both standard and derivative systems automatically.

Create the source file:

Now, update the apt cache to recognize the new Docker repository:

Step 5: Install Docker engine

With the repository configured, installing the Docker packages is the same for all distributions.

Install the Docker engine, CLI, containerd, and plugins:

Step 6: Post-installation setup

By default, Docker requires root privileges (sudo). To run Docker commands as a regular user, you need to add your user to the docker group.

Add your current user to the docker group:

Activate the group changes immediately without logging out:

Step 7: Verify installation

Finally, let's verify that the Docker service is active and capable of running containers.

Check the system service status:

Run the classic "Hello World" container to ensure the daemon can pull and run images correctly:

Conclusion

You now have a fully functional Docker installation configured with the modern DEB822 repository standard. This setup is robust and will receive updates directly from Docker's official repositories, ensuring you always have the latest patches and features regardless of whether you are running Debian, Ubuntu, or a security-focused distro like Kali.