🐳 Docker Installation Guide (Ubuntu)

This document provides the exact commands used to install Docker on an Ubuntu system, along with short explanations.

📁 1. Create Keyrings Directory

sudo install -m 0755 -d /etc/apt/keyrings

Creates a directory to securely store Docker GPG keys with proper permissions.

🔐 2. Add Docker GPG Key

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | \
    sudo gpg --dearmor -o /etc/apt/keyrings/docker-archive-keyring.gpg

Downloads Docker’s official GPG key and converts it into a format usable by APT.

🔓 3. Set Read Permissions for Key

sudo chmod a+r /etc/apt/keyrings/docker-archive-keyring.gpg

Ensures all users can read the GPG key.

📦 4. Add Docker Repository

echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/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

Adds the official Docker repository to APT sources based on system architecture and Ubuntu version.

🔄 5. Update Package Index

sudo apt update

Refreshes package lists to include Docker repository packages.

📥 6. Install Docker Packages

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

Installs:

• Docker Engine (docker-ce)
• Docker CLI
• Container runtime (containerd)
• Buildx plugin
• Docker Compose plugin

✅ 7. Verify Installation

docker ps -a

Lists all containers to confirm Docker is working.

docker image ls

Displays available Docker images.