Install Docker on popular Linux distributions: a Linux Docker installation guide

Level: Intermediate
Estimated time: ~15 minutes
Goal: Configure a secure, decentralized environment by setting up Docker to self-host personal services like Nextcloud, Bitwarden, and Matrix.

Introduction

Hosting your own "Cloud" services guarantees privacy and complete data ownership. To deploy services like Nextcloud (for file storage), Bitwarden (for password management), or Matrix (for secure communication) without dealing with complex host-level dependencies, you need isolated environments. In this tutorial, we will cover how to install Docker on Linux to build a robust, reproducible self-hosting foundation. Whether you need a complete Docker setup on Linux for a single server or a fleet, every step below applies to Ubuntu, Debian, and RHEL-compatible distributions. By the end of this Linux Docker installation guide you will have a production-ready environment configured with best-practice security defaults.

Terminology

Before proceeding, ensure you understand these core concepts:

• Docker: A platform for developing, shipping, and running applications in isolated environments.
• Docker Engine: The core client-server technology that creates and runs containers.
• Container: A standardized, executable component combining application source code with the operating system libraries and dependencies required to run it.
• Image: A read-only template with instructions for creating a container.
• Docker daemon: The background service running on the host that manages building, running, and distributing containers.
• Docker CLI: The command-line interface used to interact with the daemon.
• Docker Hub: A public registry maintained by Docker for finding and sharing container images.
• Registry: A storage and distribution system for container images.
• Installation: The process of making programs ready for execution.
• Package manager: A software tool that automates installing, upgrading, configuring, and removing programs.
• Repository: A central location where software packages are stored and maintained.
• Official Docker repository: The trusted source maintained by Docker for obtaining stable software packages.
• Package: A compressed file archive containing all the files that come with a particular application.
• Dependency: A program or library required by another program to function correctly.
• Stable release: A software version that has been thoroughly tested and is considered reliable for production use.
• Version: A unique state of the software reflecting its specific features and fixes.

Prerequisites

Before you begin, make sure the following conditions are met:

• Operating system: Ubuntu 20.04/22.04/24.04 LTS, Debian 11/12/13, or RHEL-compatible (AlmaLinux, Rocky, RHEL) 8/9/10
• Access: sudo or root access to the server
• Required knowledge: confident use of the Linux command line

Step 1: Set up the Docker repository

To ensure you get the latest secure and stable release, always use the Official Docker repository rather than the default OS repositories.

For Ubuntu:

First, update your Linux package manager index and install required packages to allow apt to use a repository over HTTPS:

sudo apt update
sudo apt install ca-certificates curl gnupg lsb-release

Add Docker's official GPG key:

sudo mkdir -m 0755 -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | \
  sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

Set up the stable repository:

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
  https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

For Debian:

The steps to install Docker on Debian mirror the Ubuntu flow but point to the Debian-specific repository URL. First, update your Linux package manager index and install required packages:

sudo apt update
sudo apt install ca-certificates curl gnupg lsb-release

Add Docker's official GPG key:

ssudo mkdir -m 0755 -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/debian/gpg | \
  sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg

Set up the stable repository:

echo \
  "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] \
  https://download.docker.com/linux/debian $(lsb_release -cs) stable" | \
  sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

For RHEL-compatible (AlmaLinux, Rocky, RHEL):

Install the yum-utils package and set up the stable repository:

sudo yum install -y yum-utils
sudo yum-config-manager \
    --add-repo \
    https://download.docker.com/linux/centos/docker-ce.repo

Result: The Docker repository is now added to your system, enabling the package manager to fetch the latest Docker packages.

Step 2: Install Docker on Ubuntu and Debian

With the Docker repository configured, proceed to install Docker Engine on Ubuntu (or Debian - the commands are identical). This step applies to both distributions.

First, remove any conflicting packages provided by the OS repositories:

sudo apt remove docker.io podman-docker containerd runc

Update the apt package index again, and use the Linux package manager to install the required components:

sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io docker-buildx-plugin \
  docker-compose-plugin

Result: The command runs, fetching the packages and any required dependency from the Docker repository. You should see the package manager complete the installation of the Docker Engine without errors.

Step 3: Install Docker on RHEL-compatible (AlmaLinux, Rocky, RHEL)

For RHEL-based systems, use yum to install the Docker Engine.

First, remove any conflicting packages provided by the OS repositories:

sudo yum remove docker docker-client docker-client-latest docker-common \
  docker-latest docker-latest-logrotate docker-logrotate docker-engine \
  podman runc

Run the following command:

sudo yum install docker-ce docker-ce-cli containerd.io docker-buildx-plugin \
  docker-compose-plugin

Result: The package manager installs the necessary packages. You will be prompted to accept the GPG key (unless you pass the -y flag); confirm it. Once complete, you will see a success message.

Step 4: Docker Engine installation verification

After installation, the Docker daemon behavior varies by distribution. On Ubuntu and Debian, docker.service starts automatically upon installation. On RHEL-family distributions, it does not.

sudo reboot

Skipping this step may cause systemctl start docker to fail with br_netfilter / addrtype errors because the running kernel no longer matches the installed modules.

Once the server is running on the current kernel, start and enable the service. The following commands are idempotent and safe to run on all systems:

sudo systemctl start docker
sudo systemctl enable docker

Result: The Docker daemon starts, and the system creates a symlink to ensure it starts automatically on every reboot.

Verify that the Docker Engine installation is successful by running the hello-world image:

sudo docker run hello-world

Result: The Docker CLI contacts the Docker daemon, pulls the hello-world image from Docker Hub, and runs a container. You should see a message stating "Hello from Docker!" printed in your terminal.

Step 5: Post-install Docker steps

By default, running Docker commands requires sudo. To run Docker commands as a non-root user, you need to add your user to the docker group. These are essential post-install Docker steps for managing your self-hosted infrastructure comfortably.

Create the docker group (if it doesn't already exist):

getent group docker || sudo groupadd docker

Add your user to the docker group:

sudo usermod -aG docker $USER

Result: Your user is added to the group. For the changes to take effect, you must log out and log back in, or activate the new group membership in the current session:

newgrp docker

After running newgrp docker (or logging out and back in), test the configuration by running a command without sudo:

docker run hello-world

Result: You should see the "Hello from Docker!" message again, confirming that your post-install Docker steps were successful.

Alternative: Quick install via convenience script

For testing or development environments, Docker provides a convenience script.

It is recommended to download the script and inspect it before execution:

curl -fsSL https://get.docker.com -o get-docker.sh
sh get-docker.sh

Step 6 (Optional): Run Docker rootless

For self-hosting environments, running Docker rootless enhances security by executing the Docker daemon and containers as a non-root user.

6.1 Prerequisites

First, stop and disable the system-wide Docker service and socket, and remove the socket file:

sudo systemctl stop docker.service docker.socket
sudo systemctl disable docker.service docker.socket
sudo rm -f /var/run/docker.sock

Verify that your user has subuid and subgid configured (usually set up automatically):

cat /etc/subuid
cat /etc/subgid

Enable lingering for your user so the daemon can start on boot:

sudo loginctl enable-linger $USER

6.2 Install additional packages

For Ubuntu/Debian:

sudo apt install docker-ce-rootless-extras uidmap dbus-user-session

For AlmaLinux/RHEL (shadow-utils provides uidmap and is usually pre-installed):

sudo yum install docker-ce-rootless-extras

6.3 Install the rootless daemon

Run the setup script from a full login session of the target user (not from sudo su or a non-login SSH shell). If you are in a non-login context, export the required variables first:

export XDG_RUNTIME_DIR=/run/user/$(id -u)
export DBUS_SESSION_BUS_ADDRESS=unix:path=$XDG_RUNTIME_DIR/bus

Then run the setup script:

dockerd-rootless-setuptool.sh install

6.4 Configure environment variables

Add the following variables to your shell configuration file (e.g., ~/.bashrc):

export PATH=/usr/bin:$PATH
export DOCKER_HOST=unix:///run/user/$(id -u)/docker.sock

Source the file or restart your shell to apply.

6.5 Limitations of rootless mode

• Cannot publish ports < 1024 (Docker provides workarounds like setcap, slirp4netns port forwarding, or routing).
• No --net=host support.
• Swarm mode and overlay networks are not supported.
• AppArmor is not supported.
• The --privileged flag does not grant host-level root access.
• Data is stored in ~/.local/share/docker (consider this for backups and quotas).
• Requires cgroup v2.
• Uses the overlayfs storage driver instead of overlay2.

Rollback

If you need to revert the Docker installation on Linux - whether it is a standard Docker for Linux setup or a rootless configuration - follow the steps below in order.

1. Rootless rollback (skip if rootless was not configured):

If you configured rootless mode, revert those changes first, before removing packages:

dockerd-rootless-setuptool.sh uninstall
rm -rf ~/.local/share/docker
sudo loginctl disable-linger $USER

2. Remove packages:

Debian/Ubuntu:

sudo apt purge docker-ce docker-ce-cli containerd.io docker-buildx-plugin \
  docker-compose-plugin docker-ce-rootless-extras
sudo rm -rf /var/lib/docker /var/lib/containerd
sudo rm -f /etc/apt/sources.list.d/docker.list /etc/apt/keyrings/docker.gpg

AlmaLinux/Rocky/RHEL:

sudo yum remove docker-ce docker-ce-cli containerd.io docker-buildx-plugin \
  docker-compose-plugin docker-ce-rootless-extras
sudo rm -rf /var/lib/docker /var/lib/containerd
sudo rm -f /etc/yum.repos.d/docker-ce.repo

3. Remove the group:

sudo groupdel docker || true

Conclusion

Your Docker installation on Linux is complete and verified. The foundation is now set up securely. You can proceed to deploy containers for your self-hosted tools, ensuring complete control over your Nextcloud files, Bitwarden vaults, and Matrix communications.

Document Version: 1.0
Last Updated: May 2026
Owner: Technical Documentation Team