How to Install Docker on CentOS / Rocky Linux

Docker is a popular platform for developing, shipping, and running applications in containers. Below are the steps to install Docker on CentOS / Rocky Linux.

Prerequisites

1. A CentOS 8 system with root or sudo privileges.
2. A stable internet connection.
3. Terminal access.

Step 1: Update the System

Before installing Docker, ensure your system is up to date.

sudo dnf update -y

Step 2: Add the Docker Repository

Docker is not available in the default CentOS 8 repositories, so you need to add the official Docker repository.

1. Install the dnf-plugins-core package to manage repositories:
   sudo dnf install -y dnf-plugins-core

2. Add the Docker repository:
   sudo dnf config-manager --add-repo=https://download.docker.com/linux/centos/docker-ce.repo

Step 3: Install Docker

1. Install Docker Engine (Community Edition) and its dependencies:
   sudo dnf install docker-ce docker-ce-cli containerd.io -y

2. Verify the installation by checking the Docker version:
   docker --version

   You should see output like: Docker version 20.10.x, build xxxxxxx.

Step 4: Start and Enable Docker

1. Start the Docker service:
   sudo systemctl start docker

2. Enable Docker to start on boot:
   sudo systemctl enable docker

3. Check the status of the Docker service:
   sudo systemctl status docker

   You should see active (running) in the output.

Step 5: Verify Docker Installation

1. Run a test container to ensure Docker is working:
   sudo docker run hello-world

   If Docker is installed correctly, you’ll see a message like:

   Hello from Docker!
   This message shows that your installation appears to be working correctly.

Manage Docker as a Non-Root User (Optional)

By default, Docker requires root privileges. To run Docker commands without sudo, add your user to the docker group:

1. Add your user to the docker group:
   sudo usermod -aG docker $USER

2. Log out and log back in for the changes to take effect.
3. Verify that you can run Docker commands without sudo:
   docker run hello-world

Uninstall Docker (Optional)

If you ever need to uninstall Docker, use the following commands:

1. Remove Docker packages:
   sudo dnf remove docker-ce docker-ce-cli containerd.io

2. Delete Docker images, containers, and volumes:
   sudo rm -rf /var/lib/docker

You’ve successfully installed Docker on CentOS 8! You can now start using Docker to deploy and manage containers. For more advanced configurations, refer to the official Docker documentation.

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