install-docker

install-docker.sh

#!/bin/bash

#===============================================================================
# Docker & Docker Compose Installation Script for Ubuntu
# Based on: https://docs.docker.com/engine/install/ubuntu/
# Includes post-installation steps from: https://docs.docker.com/engine/install/linux-postinstall/
#===============================================================================

set -e  # Exit on any error

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

print_status() {
    echo -e "${GREEN}[INFO]${NC} $1"
}

print_warning() {
    echo -e "${YELLOW}[WARNING]${NC} $1"
}

print_error() {
    echo -e "${RED}[ERROR]${NC} $1"
}

#-------------------------------------------------------------------------------
# Check if running as root or with sudo
#-------------------------------------------------------------------------------
check_root() {
    if [[ $EUID -ne 0 ]]; then
        print_error "This script must be run as root or with sudo"
        exit 1
    fi
}

#-------------------------------------------------------------------------------
# Check OS compatibility
#-------------------------------------------------------------------------------
check_os() {
    print_status "Checking OS compatibility..."
    
    if [[ ! -f /etc/os-release ]]; then
        print_error "Cannot determine OS. /etc/os-release not found."
        exit 1
    fi
    
    . /etc/os-release
    
    if [[ "$ID" != "ubuntu" ]]; then
        print_warning "This script is designed for Ubuntu. Detected: $ID"
        read -p "Do you want to continue anyway? (y/N): " -n 1 -r
        echo
        if [[ ! $REPLY =~ ^[Yy]$ ]]; then
            exit 1
        fi
    fi
    
    print_status "Detected: $PRETTY_NAME"
}

#-------------------------------------------------------------------------------
# Uninstall old/conflicting versions
#-------------------------------------------------------------------------------
uninstall_old_versions() {
    print_status "Removing any old or conflicting Docker packages..."
    
    # List of packages to remove
    local packages_to_remove=(
        docker.io
        docker-compose
        docker-compose-v2
        docker-doc
        podman-docker
        containerd
        runc
    )
    
    # Get list of installed packages from the list
    local installed_packages=""
    for pkg in "${packages_to_remove[@]}"; do
        if dpkg -l "$pkg" &>/dev/null 2>&1; then
            installed_packages+=" $pkg"
        fi
    done
    
    if [[ -n "$installed_packages" ]]; then
        print_status "Removing:$installed_packages"
        apt-get remove -y $installed_packages || true
    else
        print_status "No conflicting packages found."
    fi
}

#-------------------------------------------------------------------------------
# Set up Docker's apt repository
#-------------------------------------------------------------------------------
setup_repository() {
    print_status "Setting up Docker's apt repository..."
    
    # Update package index
    apt-get update
    
    # Install prerequisites
    print_status "Installing prerequisites (ca-certificates, curl)..."
    apt-get install -y ca-certificates curl
    
    # Create keyrings directory
    install -m 0755 -d /etc/apt/keyrings
    
    # Download and install Docker's official GPG key
    print_status "Adding Docker's official GPG key..."
    curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
    chmod a+r /etc/apt/keyrings/docker.asc
    
    # Add the repository to apt sources
    print_status "Adding Docker repository to apt sources..."
    
    # Get the Ubuntu codename
    . /etc/os-release
    CODENAME="${UBUNTU_CODENAME:-$VERSION_CODENAME}"
    
    tee /etc/apt/sources.list.d/docker.sources > /dev/null <<EOF
Types: deb
URIs: https://download.docker.com/linux/ubuntu
Suites: ${CODENAME}
Components: stable
Signed-By: /etc/apt/keyrings/docker.asc
EOF
    
    # Update package index again
    apt-get update
    
    print_status "Docker repository configured successfully."
}

#-------------------------------------------------------------------------------
# Install Docker Engine packages
#-------------------------------------------------------------------------------
install_docker() {
    print_status "Installing Docker Engine, CLI, containerd, and plugins..."
    
    apt-get install -y \
        docker-ce \
        docker-ce-cli \
        containerd.io \
        docker-buildx-plugin \
        docker-compose-plugin
    
    print_status "Docker packages installed successfully."
}

#-------------------------------------------------------------------------------
# Post-installation: Configure docker group for non-root access
#-------------------------------------------------------------------------------
configure_docker_group() {
    print_status "Configuring Docker group for non-root access..."
    
    # Create docker group if it doesn't exist
    if ! getent group docker > /dev/null 2>&1; then
        groupadd docker
        print_status "Created 'docker' group."
    else
        print_status "'docker' group already exists."
    fi
    
    # Get the actual user (not root when using sudo)
    local ACTUAL_USER="${SUDO_USER:-$USER}"
    
    if [[ "$ACTUAL_USER" != "root" ]]; then
        # Add user to docker group
        if ! groups "$ACTUAL_USER" | grep -q '\bdocker\b'; then
            usermod -aG docker "$ACTUAL_USER"
            print_status "Added user '$ACTUAL_USER' to the 'docker' group."
            print_warning "You need to log out and back in for group changes to take effect."
            print_warning "Or run: newgrp docker"
        else
            print_status "User '$ACTUAL_USER' is already in the 'docker' group."
        fi
    else
        print_warning "Running as root. No user to add to docker group."
    fi
}

#-------------------------------------------------------------------------------
# Post-installation: Enable Docker to start on boot
#-------------------------------------------------------------------------------
enable_docker_on_boot() {
    print_status "Enabling Docker to start on boot..."
    
    systemctl enable docker.service
    systemctl enable containerd.service
    
    print_status "Docker services enabled for startup."
}

#-------------------------------------------------------------------------------
# Start Docker service
#-------------------------------------------------------------------------------
start_docker() {
    print_status "Starting Docker service..."
    
    systemctl start docker
    
    if systemctl is-active --quiet docker; then
        print_status "Docker service is running."
    else
        print_error "Failed to start Docker service."
        exit 1
    fi
}

#-------------------------------------------------------------------------------
# Verify installation
#-------------------------------------------------------------------------------
verify_installation() {
    print_status "Verifying Docker installation..."
    
    echo ""
    echo "========================================"
    echo "Docker Version:"
    echo "========================================"
    docker version
    
    echo ""
    echo "========================================"
    echo "Docker Compose Version:"
    echo "========================================"
    docker compose version
    
    echo ""
    print_status "Running hello-world container to verify..."
    docker run --rm hello-world
    
    echo ""
    print_status "Installation verification complete!"
}

#-------------------------------------------------------------------------------
# Print summary
#-------------------------------------------------------------------------------
print_summary() {
    echo ""
    echo "========================================"
    echo -e "${GREEN}Docker Installation Complete!${NC}"
    echo "========================================"
    echo ""
    echo "Installed components:"
    echo "  - Docker Engine (docker-ce)"
    echo "  - Docker CLI (docker-ce-cli)"
    echo "  - containerd.io"
    echo "  - Docker Buildx plugin"
    echo "  - Docker Compose plugin"
    echo ""
    echo "Post-installation configuration:"
    echo "  - Docker group configured"
    echo "  - Docker enabled to start on boot"
    echo ""
    
    local ACTUAL_USER="${SUDO_USER:-$USER}"
    if [[ "$ACTUAL_USER" != "root" ]]; then
        echo -e "${YELLOW}IMPORTANT:${NC}"
        echo "  To run Docker without sudo, either:"
        echo "  1. Log out and log back in, OR"
        echo "  2. Run: newgrp docker"
        echo ""
    fi
    
    echo "Useful commands:"
    echo "  docker --version          # Check Docker version"
    echo "  docker compose version    # Check Docker Compose version"
    echo "  docker info               # Display system-wide information"
    echo "  docker run hello-world    # Test Docker installation"
    echo ""
}

#-------------------------------------------------------------------------------
# Main function
#-------------------------------------------------------------------------------
main() {
    echo "========================================"
    echo "Docker Installation Script for Ubuntu"
    echo "========================================"
    echo ""
    
    check_root
    check_os
    
    echo ""
    read -p "This will install Docker and Docker Compose. Continue? (Y/n): " -n 1 -r
    echo ""
    if [[ $REPLY =~ ^[Nn]$ ]]; then
        print_status "Installation cancelled."
        exit 0
    fi
    
    echo ""
    
    uninstall_old_versions
    setup_repository
    install_docker
    configure_docker_group
    enable_docker_on_boot
    start_docker
    verify_installation
    print_summary
}

# Run main function
main "$@"