Installing and Configuring Docker on Linux

Prerequisites

Before installing Docker on a Linux system, ensure you have:

1. A 64-bit installation of a compatible Linux distribution.
2. Root or a user with sudo privileges.
3. Internet access for downloading packages.

Supported Linux Distributions

Docker supports several Linux distributions. This guide will cover the installation process for:

• Ubuntu
• CentOS
• Debian

Table 1: Supported Distributions

Step-by-Step Installation

Installing Docker on Ubuntu

1. Update Your System:
   bash
sudo apt update
sudo apt upgrade -y

2. Install Required Packages:
   bash
sudo apt install apt-transport-https ca-certificates curl software-properties-common -y

3. Add Docker’s Official GPG Key:
   bash
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

4. Set Up Docker Repository:
   bash
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

5. Install Docker Engine:
   bash
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io -y

6. Verify Installation:
   bash
sudo systemctl status docker
docker --version

Installing Docker on CentOS

1. Update Your System:
   bash
sudo yum update -y

2. Install Required Packages:
   bash
sudo yum install -y yum-utils

3. Set Up Docker Repository:
   bash
sudo yum-config-manager --add-repo https://download.docker.com/linux/centos/docker-ce.repo

4. Install Docker Engine:
   bash
sudo yum install docker-ce docker-ce-cli containerd.io -y

5. Start Docker:
   bash
sudo systemctl start docker
sudo systemctl enable docker

6. Verify Installation:
   bash
sudo systemctl status docker
docker --version

Installing Docker on Debian

1. Update Your System:
   bash
sudo apt update
sudo apt upgrade -y

2. Install Required Packages:
   bash
sudo apt install apt-transport-https ca-certificates curl gnupg lsb-release -y

3. Add Docker’s Official GPG Key:
   bash
curl -fsSL https://download.docker.com/linux/debian/gpg | sudo gpg --dearmor -o /usr/share/keyrings/docker-archive-keyring.gpg

4. Set Up Docker Repository:
   bash
echo "deb [arch=$(dpkg --print-architecture) signed-by=/usr/share/keyrings/docker-archive-keyring.gpg] https://download.docker.com/linux/debian $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null

5. Install Docker Engine:
   bash
sudo apt update
sudo apt install docker-ce docker-ce-cli containerd.io -y

6. Verify Installation:
   bash
sudo systemctl status docker
docker --version

Post-Installation Steps

Managing Docker as a Non-Root User

1. Create Docker Group:
   bash
sudo groupadd docker

2. Add Your User to the Docker Group:
   bash
sudo usermod -aG docker $USER

3. Apply the New Group Membership:
   bash
newgrp docker

4. Verify Docker Runs Without sudo:
   bash
docker run hello-world

Configuring Docker to Start on Boot

Enable Docker to start at boot time:

sudo systemctl enable docker

Checking Docker Service Status

To check the status of the Docker service:

sudo systemctl status docker

Docker Configuration Files

Docker Daemon Configuration File

Docker’s configuration parameters are stored in /etc/docker/daemon.json. Example configuration:

{
  "log-driver": "json-file",
  "log-level": "warn",
  "storage-driver": "overlay2"
}

Reload Daemon and Restart Docker

After making changes to daemon.json, reload and restart Docker:

sudo systemctl daemon-reload
sudo systemctl restart docker

Troubleshooting Common Issues

Docker Service Fails to Start

1. Check Docker Logs:
   bash
sudo journalctl -u docker

2. Verify Configuration:
   Ensure no syntax errors in /etc/docker/daemon.json.

Problems with Docker Commands

Ensure the user is added to the docker group:

groups $USER

If not, follow the steps under “Managing Docker as a Non-Root User.”

Summary Table: Common Commands

By following these detailed instructions, you can confidently install and configure Docker on a Linux system, enabling you to efficiently manage containerized applications.