Docker has become an essential tool in modern software development, offering a streamlined way to build, test, and deploy applications within isolated environments known as containers. A container is a compact, self-contained unit that encapsulates the application along with all its dependencies—libraries, configuration files, and runtime requirements—allowing it to run consistently across different computing environments.

This portability and consistency make Docker indispensable for developers today. Whether deploying on local machines or cloud infrastructure, Docker ensures that applications behave the same way everywhere.

Docker offers two primary editions: Docker Community Edition (CE) and Docker Enterprise Edition (EE). The former is open-source and free to use, while the latter is a commercial offering tailored for enterprise environments.

In this guide, we will walk through how to install Docker CE on both Rocky Linux and AlmaLinux distributions.

Step 1: Add Docker Repository on Rocky Linux

By default, Docker is not included in the standard package repositories of Rocky Linux. However, Docker provides an official repository which we can add manually.

To do so, execute the following command in your terminal:

<code>$ sudo dnf config-manager --add-repo=https://download.docker.com/linux/centos/docker-ce.repo</code>

Step 2: Install Docker in Rocky Linux / AlmaLinux

Once the repository has been added, update your system’s package list before proceeding with the installation.

Run the update command:

<code>$ sudo dnf update</code>

Then install Docker CE, the Docker CLI, and containerd using the following command:

<code>$ sudo dnf install -y docker-ce docker-ce-cli containerd.io</code>

After installation, verify the installed version of Docker:

<code>$ docker --version

<strong>Docker version 20.10.8, build 3967b7d</strong></code>

Step 3: Start and Enable Docker Service

Now that Docker is installed, we need to start the Docker service. Before doing so, ensure that it starts automatically at boot time.

Enable the Docker service:

<code>$ sudo systemctl enable docker</code>

Start the Docker daemon:

<code>$ sudo systemctl start docker</code>

Check the status of the Docker service to confirm it's running properly:

<code>$ sudo systemctl status docker</code>

Great! The Docker service is up and running.

Step 4: Add User to the Docker Group

By default, only the root user has permission to execute Docker commands. To allow a regular user to run Docker without sudo privileges, we must add them to the docker group, which is created automatically during installation.

For example, to add the user tecmint to the docker group:

<code>$ sudo usermod -aG docker tecmint</code>

You can verify the group membership of the user using the id command:

<code>$ id tecmint</code>

Step 5: Test Docker Installation on Rocky Linux

To verify that Docker is working correctly, let’s run the official hello-world container:

<code>$ docker run hello-world</code>

This command downloads the hello-world image from Docker Hub and runs it inside a container. It outputs a message confirming successful installation.

Let’s try something more advanced. We’ll pull an Ubuntu image and interact with it.

Pull Ubuntu Image

Download the latest Ubuntu image using:

<code>$ docker pull ubuntu</code>

List available images:

<code>$ docker images</code>

Run Ubuntu Container

To access the shell of the Ubuntu container:

<code>$ docker run -it ubuntu</code>

Inside the container, you can run commands just like on a regular Ubuntu system. When finished, type exit to leave the container environment.

Final Thoughts

That concludes our guide. You now have Docker CE successfully installed on either Rocky Linux or AlmaLinux. You’ve also learned how to pull Docker images and run interactive containers—laying the foundation for further exploration into Docker-based development and deployment workflows.

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