Installing Docker

Before we containerize our e-commerce app, we need Docker running on your machine. The installation is straightforward on any operating system.

Docker Desktop

• Docker Engine - The runtime that runs containers
• Docker CLI - Command-line interface
• Docker Compose - Tool for multi-container apps
• Docker Desktop GUI - Visual management (optional)

Installation by Platform

macOS

• Download Docker Desktop from [docker.com/products/docker-desktop](https://www.docker.com/products/docker-desktop)
• Open the .dmg file
• Drag Docker to Applications
• Launch Docker from Applications
• Wait for the whale icon in the menu bar to stop animating

Windows

• Download Docker Desktop from [docker.com/products/docker-desktop](https://www.docker.com/products/docker-desktop)
• Run the installer
• Enable WSL 2 when prompted (recommended)
• Restart your computer
• Launch Docker Desktop

Linux (Ubuntu/Debian)

# Update packages
sudo apt-get update

# Install prerequisites
sudo apt-get install ca-certificates curl gnupg

# Add Docker's GPG key
sudo install -m 0755 -d /etc/apt/keyrings
curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo gpg --dearmor -o /etc/apt/keyrings/docker.gpg
sudo chmod a+r /etc/apt/keyrings/docker.gpg

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

# Install Docker
sudo apt-get update
sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

# Add your user to the docker group (avoids needing sudo)
sudo usermod -aG docker $USER

Log out and back in for the group change to take effect.

Verify Installation

Open a terminal and run:

docker --version

Docker version 24.0.7, build afdd53b

Your version may differ - anything 20+ is fine.

Now run the classic test:

docker run hello-world

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
...
Hello from Docker!
This message shows that your installation appears to be working correctly.

If you see this, Docker is ready to go.

Understanding Docker Architecture

Docker uses a client-server architecture:

┌──────────────────────────────────────────────────────┐
│                    Your Computer                      │
│                                                       │
│  ┌─────────────┐          ┌─────────────────────┐   │
│  │ Docker CLI  │  ──API─▶ │   Docker Daemon     │   │
│  │             │          │   (dockerd)         │   │
│  │ $ docker    │          │                     │   │
│  │   run       │          │  ┌───────────────┐  │   │
│  │   build     │          │  │  Containers   │  │   │
│  │   pull      │          │  └───────────────┘  │   │
│  └─────────────┘          │  ┌───────────────┐  │   │
│                           │  │    Images     │  │   │
│                           │  └───────────────┘  │   │
│                           └─────────────────────┘   │
└──────────────────────────────────────────────────────┘

When you run docker run hello-world:

• CLI sends command to daemon
• Daemon checks for hello-world image locally
• If not found, pulls from Docker Hub
• Daemon creates and runs a container from the image
• Container output is sent back to CLI

Essential Commands Check

Verify these commands work:

# Check Docker Compose (for multi-container apps)
docker compose version

# List running containers (empty for now)
docker ps

# List all containers (including stopped)
docker ps -a

# List downloaded images
docker images

Configure Resources (Optional)

For e-commerce development, you might need more resources. In Docker Desktop:

• Click the gear icon (Settings)
• Go to Resources
• Recommended minimums:

- Memory: 4GB+

- Disk: 20GB+

For our e-commerce stack (API + database + cache), 4GB RAM is comfortable.

Quick Troubleshooting

• Make sure Docker Desktop is running (whale icon in system tray)
• On Linux: sudo systemctl start docker

• On Linux: Add yourself to docker group: sudo usermod -aG docker $USER, then log out/in
• Or prefix commands with sudo

• Docker runs in a Linux VM on these systems
• Allocate more RAM in Docker Desktop settings
• Use volume caching options (covered later)

Key Takeaways

• Docker Desktop is the easiest installation method
• docker --version verifies installation
• docker run hello-world tests the full system
• Docker uses a client-server architecture
• Daemon runs containers, CLI sends commands

Next, let's run real containers and explore how they work!