Ubuntu Docker Installation

docker.sh

#!/bin/bash

set -e

# Ensure script is executed as root
if [ "$(id -u)" -ne 0 ]; then
  echo "❌ Please run this script with sudo or as root."
  exit 1
fi

echo "🚀 Starting Docker CE installation on Ubuntu..."

# 1. Remove old/unofficial Docker packages
echo "Removing old Docker packages if any..."
apt-get remove -y docker.io docker-doc docker-compose docker-compose-v2 podman-docker containerd runc || true

# 2. Update apt index and install prerequisites
echo "Updating package index and installing prerequisites..."
apt-get update
apt-get install -y ca-certificates curl gnupg lsb-release

# 3. Add Docker’s official GPG key
echo "Adding Docker GPG key..."
mkdir -p /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg \
  | gpg --dearmor -o /etc/apt/keyrings/docker.gpg
chmod a+r /etc/apt/keyrings/docker.gpg

# 4. Add Docker apt repository
echo "Adding Docker repository..."
ARCH=$(dpkg --print-architecture)
CODENAME=$(. /etc/os-release && echo "${UBUNTU_CODENAME:-$VERSION_CODENAME}")
echo "deb [arch=$ARCH signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $CODENAME stable" \
  | tee /etc/apt/sources.list.d/docker.list > /dev/null

# 5. Update apt index
echo "Updating apt-index with the new Docker repository..."
apt-get update

# 6. Install Docker Engine and related components
echo "Installing Docker Engine and components..."
apt-get install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# 7. Start and enable Docker service
echo "Enabling and starting Docker service..."
systemctl enable docker
systemctl start docker

# 8. Post-install: allow non-root users to use Docker (optional)
if [ "$1" == "--non-root" ] || [ "$1" == "-u" ]; then
  echo "Adding $SUDO_USER (or current user) to docker group..."
  TARGET_USER="${SUDO_USER:-$(logname)}"
  groupadd docker 2>/dev/null || true
  usermod -aG docker "$TARGET_USER"
  echo "✅ User $TARGET_USER added to 'docker' group. Re-login or run 'newgrp docker' to apply changes."
fi

# 9. Test Docker installation
echo "Running hello-world test..."
docker run --rm hello-world

echo "🎉 Docker installation completed successfully!"

Usage Instructions

1. Save the script to a file, e.g., docker.sh.

2. Make it executable:

   chmod +x docker.sh

3. Run it with root privileges:

   sudo ./docker.sh

4. Optional: To allow your user to run Docker without sudo, pass the flag:

   sudo ./docker.sh --non-root

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