Bash script to automate the installation of Docker CE on Ubuntu systems. The script ensures that all necessary prerequisites are met and sets up Docker to run as a service, automatically starting at boot. It also adds the current user to the Docker group to allow running Docker commands without `sudo`.

install_docker_ubuntu.sh

#!/bin/bash

# This script is intended for Ubuntu distributions to automate the Docker installation.
# 
# Additional Setup Instructions:
# 1. Save the script as `install-docker-ubuntu.sh`.
# 2. Make the script executable with the command: `chmod +x install-docker-ubuntu.sh`.
# 3. Run the script using `sudo ./install-docker-ubuntu.sh`.
# 4. After the installation, log out and log back into your system to ensure that group changes take effect. This is required to run Docker commands without `sudo`.

# Alert user about root privileges requirement
if [ "$(id -u)" -ne 0 ]; then
    echo "Please run this script with sudo or as root."
    exit 1
fi

# Update the apt package index to ensure access to the latest package listings
sudo apt update

# Install packages to allow apt to use a repository over HTTPS
sudo apt install -y apt-transport-https ca-certificates curl software-properties-common

# Import Docker's official public key to verify packages
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

# Add Docker's stable repository to fetch and install its latest version
sudo add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"

# Update the package index again after adding Docker's repository
sudo apt update

# Install Docker Community Edition
sudo apt install -y docker-ce

# Start Docker service immediately after the installation
sudo systemctl start docker

# Set Docker service to start automatically upon system boot
sudo systemctl enable docker

# Add the current user to the Docker group to manage Docker without superuser privileges
sudo usermod -aG docker $USER

# Machine-readable output to verify Docker install status and version
echo "Docker installed successfully."
echo "Docker service status: $(sudo systemctl is-active docker)"
echo "Docker version: $(sudo docker --version)"

# Inform the user that a re-login is necessary to apply user group changes
echo "Please log out and log back in to apply the group changes."