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      • Install Docker on CentOS

      This chapter covers how to install and configure Docker Engine on CentOS.

      System Requirements

      Docker Engine supports the following CentOS versions:

      • CentOS 9 Stream
      • CentOS 8 Stream
      • CentOS 7 (maintenance mode)

      Hardware requirements: 64-bit processor, kernel 3.10+, at least 2GB RAM (4GB+ recommended). The centos-extras repository must be enabled.

      Uninstall Old Versions

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

      1. Install yum-utils

      sudo yum install -y yum-utils

      2. Add Docker Repository

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

      3. Install Docker Engine

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

      4. Start Docker

      sudo systemctl start docker

      5. Verify Installation

      sudo docker run hello-world

      Convenience Script

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

      Post-Installation Setup

      Run Docker Without sudo

      sudo groupadd docker
sudo usermod -aG docker $USER
newgrp docker

      Enable on Boot

      sudo systemctl enable docker.service
sudo systemctl enable containerd.service

      Common Issues

      firewalld Conflicts

      # Restart Docker after firewalld changes
sudo systemctl restart docker

# Or allow Docker interface
sudo firewall-cmd --zone=trusted --add-interface=docker0 --permanent
sudo firewall-cmd --reload

      SELinux Issues

      # Check SELinux status
getenforce

# Temporarily set to permissive
sudo setenforce 0

# Permanent change
sudo sed -i 's/SELINUX=enforcing/SELINUX=permissive/' /etc/selinux/config

      💡 In production, keep SELinux enabled and configure policies for compatibility.

      CentOS 7 Kernel Upgrade

      CentOS 7 has an older kernel. Consider upgrading for better Docker support:

      sudo rpm --import https://www.elrepo.org/RPM-GPG-KEY-elrepo.org
sudo yum install https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm
sudo yum --enablerepo=elrepo-kernel install kernel-ml
sudo reboot

      Uninstall Docker

      sudo yum remove docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
sudo rm -rf /var/lib/docker
sudo rm -rf /var/lib/containerd

      Further Reading