Set Up Docker on a CentOS VPS

Why Docker

• Portable. A container holds the app and its dependencies, so it runs the same everywhere.
• Scalable. Start more containers when you need more capacity.
• Isolated. Each container is separate from the others and from the host.
• Efficient. Containers use fewer resources than virtual machines.

What you need

• A CentOS (or compatible, such as AlmaLinux or Rocky Linux) VPS, 64-bit.
• Root or sudo access.
• A supported version of the system. Check the Docker documentation for the list.
• Internet access to download packages.
• Open ports in the firewall for the services you run in containers.

Step 1: Update the system

sudo yum update -y

Remove old Docker versions if any:

sudo yum remove docker docker-client docker-client-latest docker-common docker-latest docker-latest-logrotate docker-logrotate docker-engine

Step 2: Add the Docker repository

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

Step 3: Install Docker Engine

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

Step 4: Start Docker and enable it at boot

sudo systemctl start docker
sudo systemctl enable docker
sudo systemctl status docker

Step 5: Test it

sudo docker run hello-world

If you see the "Hello from Docker!" message, Docker works.

Run Docker as a normal user (optional)

sudo usermod -aG docker $USER

Log out and in again. Members of the docker group have root-equivalent power, so add only people you trust.

Useful commands

docker ps              # running containers
docker images          # downloaded images
docker pull nginx      # get an image
docker run -d -p 80:80 nginx

If firewalld is on, open the ports you publish, for example sudo firewall-cmd --add-port=80/tcp --permanent && sudo firewall-cmd --reload.

Quick recap

• Add the Docker CE repository, install docker-ce, start the service and run hello-world.