Module 2 Lesson 2: Installing Docker

Before we can run containers, we need the engine. This lesson covers the installation path for the three major operating systems.

1. Windows: Docker Desktop

Docker Desktop is the recommended way to run Docker on Windows. It uses WSL 2 (Windows Subsystem for Linux) for the best performance.

• Prerequisites: Windows 10/11 (Pro, Enterprise, or Home) with WSL 2 enabled.
• Steps:
  1. Download the "Docker Desktop for Windows" installer from docker.com.
  2. Run the installer. Ensure the "Use WSL 2 instead of Hyper-V" option is checked.
  3. Restart your computer.
  4. Open the Docker Desktop app. Wait for the whale icon in the taskbar to stay still.

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2. Mac: Docker Desktop

Docker Desktop for Mac provides a seamless experience for both Intel and Apple Silicon (M1/M2/M3) chips.

• Prerequisites: macOS version 11 or newer.
• Steps:
  1. Download the correct installer (Intel vs. Apple Chip) from docker.com.
  2. Double-click the .dmg and drag the Docker icon to your Applications folder.
  3. Launch Docker from your Applications.
  4. Grant the necessary permissions for networking and privileged access.

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3. Linux (Ubuntu Example)

On Linux, we usually install the Docker Engine (no GUI) directly.

• Steps:
  1. Update your packages: sudo apt-get update.
  2. Install prerequisites: sudo apt-get install ca-certificates curl gnupg.
  3. Add Docker’s official GPG key and repository.
  4. Install the engine: sudo apt-get install docker-ce docker-ce-cli containerd.io.
• Post-Install (Crucial): By default, you have to run sudo docker. To run without sudo, add your user to the docker group:

  sudo usermod -aG docker $USER
  

  (Log out and log back in for this to take effect).

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4. Verifying the Installation

Open your terminal (Command Prompt, PowerShell, or Terminal) and run:

docker --version

Then, try the most famous first command:

docker run hello-world

If you see: "Hello from Docker! This message shows that your installation appears to be working correctly," you are ready!

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Troubleshooting Common Issues

• "Docker daemon not running": On Windows/Mac, make sure the Docker Desktop app is actually open.
• "WSL 2 installation is incomplete": Follow the link provided in the Docker error message to update the Linux kernel component from Microsoft.
• "Permission Denied": On Linux, make sure you performed the usermod step above.

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Exercise: System Check

1. Run docker info in your terminal. Look for the "Operating System" and "Kernel Version" entries. What do they say?
2. If you are on Windows/Mac, check the Docker Desktop settings. How many CPUs and how much RAM is Docker allowed to use by default?
3. Why is it better to use WSL 2 on Windows instead of the older "Hyper-V" backend? (Search for "Docker WSL2 benefits").

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Summary

You now have a working Docker environment. Whether you chose the GUI-friendly Desktop version or the raw Linux Engine, the core commands we learn next will work exactly the same way.

Next Lesson: We master the command line: Core Docker CLI commands.