Preparing the Container Learning Environment

This document explains how to install the necessary tools and prepare your environment before starting the container course. It covers Docker installation, Docker Compose verification, account creation, and editor setup.

Complete all steps in this document before starting the course, and make sure the final verification commands produce the expected output.

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1. System Requirements

Docker requires the following minimum specifications to run.

Item	Minimum	Recommended
RAM	4GB	8GB or more
Free disk space	10GB	20GB or more
CPU	2 cores	4 cores or more
Virtualization	VT-x/AMD-V enabled in BIOS	-

Verification (Linux environment)

free -h

Expected Output

               total        used        free      shared  buff/cache   available
Mem:           7.8Gi       2.1Gi       3.2Gi       120Mi       2.5Gi       5.3Gi

If total is 4Gi or more, the minimum requirement is met.

df -h /

Expected Output

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda1       50G   15G   33G  32% /

If Avail is 10G or more, you are good to go.

Warning

If RAM is less than 4GB, the system may slow down when running multiple Docker containers. During learning, it is recommended to close unused programs to free up memory.

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2. Installing Docker

The installation method varies by operating system. Follow the section that matches your environment.

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2.1 Windows: Installing Docker Desktop

Prerequisites

• WSL2 must be installed (refer to 01-linux/00-prerequisites.md).
• The WSL2 backend must be enabled. Docker Desktop runs on top of WSL2.

Installation Steps

Step 1: Download Docker Desktop.

Go to https://www.docker.com/products/docker-desktop/ and click "Download for Windows".

Step 2: Run the installer.

When the installation wizard appears, verify the following options:

• "Use WSL 2 instead of Hyper-V" checked (required)
• "Add shortcut to desktop" checked (optional)

Step 3: Reboot your computer after installation is complete.

Step 4: Launch Docker Desktop.

Search for "Docker Desktop" in the Start menu and launch it. On the first launch, a terms of service agreement screen will appear. Agree and proceed.

Step 5: Verify WSL2 integration.

Click the gear icon (Settings) at the top of Docker Desktop and:

1. General tab: Verify that "Use the WSL 2 based engine" is checked.
2. Resources > WSL Integration tab: Verify that your Ubuntu distribution is enabled.

Step 6: Verify that Docker works from the WSL2 terminal.

Open the WSL2 Ubuntu terminal and run:

docker --version

Expected Output

Docker version 27.5.1, build 9f9e405

Warning

• Docker Desktop must be running for the docker command to work in WSL2. Check that Docker is running in the system tray icon.
• If you see "Docker Desktop - WSL2 backend requires WSL update", run wsl --update in PowerShell (as administrator).

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2.2 Mac: Installing Docker Desktop

Apple Silicon vs Intel Check

First, check which chip your Mac has.

Click the Apple menu in the top left > "About This Mac".

• Chip: Apple M1, M2, M3, etc. -- Apple Silicon
• Processor: Intel Core -- Intel

Installation Steps

Step 1: Download Docker Desktop.

Go to https://www.docker.com/products/docker-desktop/ and:

• Apple Silicon Mac: Click "Download for Mac - Apple Silicon"
• Intel Mac: Click "Download for Mac - Intel Chip"

Warning

Installing the wrong version for your chip type may cause it to not work properly. Make sure to select the version that matches your chip.

Step 2: Open the downloaded .dmg file and drag the Docker icon to the Applications folder.

Step 3: Launch Docker from Applications.

On the first launch, it may request system access permissions. Allow them.

Step 4: When the Docker icon (whale) appears in the menu bar, installation is complete.

Step 5: Verify in the terminal.

docker --version

Expected Output

Docker version 27.5.1, build 9f9e405

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2.3 Linux: Direct Docker Engine Installation

On Linux, install Docker Engine directly instead of Docker Desktop.

Installation Steps

Step 1: Remove any previous versions if present.

sudo apt remove docker docker-engine docker.io containerd runc 2>/dev/null

Expected Output

Reading package lists... Done
Building dependency tree... Done

This will proceed without errors even if the packages are not already present.

Step 2: Install required packages.

sudo apt update && sudo apt install -y ca-certificates curl gnupg

Step 3: Add the official Docker 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

Step 4: Add the 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

Step 5: Install Docker Engine.

sudo apt update && sudo apt install -y docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin

Expected Output (final portion)

Setting up docker-ce (5:27.5.1-1~ubuntu.22.04~jammy) ...
Processing triggers for man-db (2.10.2-1) ...

Step 6: Add the current user to the docker group.

sudo usermod -aG docker $USER

Warning

You must log out and log back in or reboot after the group change. Until you log back in, you need to use sudo docker to run commands.

After logging back in, verify without sudo:

docker --version

Expected Output

Docker version 27.5.1, build 9f9e405

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3. Verifying Docker Installation: hello-world

The most reliable way to verify that Docker is installed correctly is to run the hello-world container.

docker run hello-world

Expected Output

Unable to find image 'hello-world:latest' locally
latest: Pulling from library/hello-world
c1ec31eb5944: Pull complete
Digest: sha256:d211f485f2dd1dee407a80973c8f129f00d54604d2c90732e8e320e5038a0348
Status: Downloaded newer image for hello-world:latest

Hello from Docker!
This message shows that your installation appears to be working correctly.

To generate this message, Docker took the following steps:
 1. The Docker client contacted the Docker daemon.
 2. The Docker daemon pulled the "hello-world" image from the Docker Hub.
 3. The Docker daemon created a new container from that image which runs the
    executable that produces the output you are currently reading.
 4. The Docker daemon streamed that output to the Docker client, which sent it
    to your terminal.
...

Explanation

• Unable to find image ... locally: The image is not available locally, so it is being downloaded from Docker Hub.
• Hello from Docker!: If this message appears, Docker is fully operational.

Warning

If you get a Cannot connect to the Docker daemon error:

• Windows/Mac: Verify that Docker Desktop is running.
• Linux: Verify that the Docker service is running.

sudo systemctl status docker

Expected Output

● docker.service - Docker Application Container Engine
     Loaded: loaded (/lib/systemd/system/docker.service; enabled; vendor preset: enabled)
     Active: active (running) since ...

If it shows active (running), it is working correctly. If it is not running:

sudo systemctl start docker
sudo systemctl enable docker

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4. Verifying Docker Compose

Docker Compose is a tool for defining and running multiple containers at once. It is included by default with Docker Desktop, and if you installed Docker Engine on Linux, it was installed as a plugin.

docker compose version

Expected Output

Docker Compose version v2.32.4

Warning

Older versions used docker-compose (with a hyphen), but the current version uses docker compose (with a space).

If the docker compose command does not work:

docker-compose --version

If that does not work either, a separate installation is needed:

sudo apt install docker-compose-plugin -y

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5. Creating a Docker Hub Account

Docker Hub is a public registry for storing and sharing Docker images. Downloading (pulling) images is possible without an account, but uploading (pushing) images requires one.

Creating an Account

1. Go to https://hub.docker.com.
2. Click "Sign Up".
3. Enter a username, email, and password to create your account.

Logging in from the Terminal

docker login

Expected Output

Log in with your Docker ID or email address to push and pull images from Docker Hub.
Username: myuser
Password:
Login Succeeded

Explanation

• Nothing will appear on screen while typing the password. This is normal.
• If Login Succeeded appears, the login is complete.

Practical Tip

Login credentials are stored in ~/.docker/config.json. On shared servers, make it a habit to run docker logout after completing your work.

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6. Installing VS Code + Docker Extension

Installing the Docker extension in VS Code allows you to visually manage containers, images, volumes, and more. It also provides syntax highlighting and auto-completion when writing Dockerfiles.

Installing VS Code

If you do not have VS Code yet:

1. Download it from https://code.visualstudio.com.
2. Install the version for your operating system.

Installing the Docker Extension

Method 1: Install from within VS Code

1. Open VS Code.
2. Click the Extensions icon in the left sidebar (four squares icon).
3. Type Docker in the search bar.
4. Find "Docker" (by Microsoft) and click Install.

Method 2: Install from the terminal

code --install-extension ms-azuretools.vscode-docker

Expected Output

Installing extension 'ms-azuretools.vscode-docker'...
Extension 'ms-azuretools.vscode-docker' v1.x.x was successfully installed.

Verifying Installation

If a whale (Docker) icon appears in the VS Code left sidebar, the installation is complete. Clicking this icon lets you view currently running containers, image lists, and more.

Practical Tip

If you are using VS Code with WSL2, it is also helpful to install the "Remote - WSL" extension. It allows you to edit files inside WSL2 directly from VS Code.

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7. Resource Allocation Settings (Docker Desktop)

If you are using Docker Desktop, you can configure the CPU and memory available to Docker.

How to Configure

1. Open Docker Desktop.
2. Click the gear icon (Settings).
3. Select the Resources tab.

Recommended Settings

Item	Recommended for Learning
CPUs	2 or more
Memory	4GB or more (6-8GB if possible)
Swap	1GB
Disk image size	20GB or more

After Changing Settings

Click "Apply & Restart" to restart Docker with the new settings applied.

Warning

• Allocating too much memory may slow down the host (Windows/Mac) system. It is best not to exceed half of your total RAM.
• On Windows with the WSL2 backend, the settings may not appear in the Resources tab. In this case, configure them using the WSL2 .wslconfig file.

WSL2 Memory Limit (.wslconfig)

To limit WSL2 memory on Windows, create a file at C:\Users\YourUsername\.wslconfig:

[wsl2]
memory=6GB
processors=2
swap=2GB

After saving, run in PowerShell:

wsl --shutdown

The settings will take effect when you reopen WSL2.

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8. Final Environment Verification

Once all installations are complete, run the following commands to verify.

8.1 Docker Version Check

docker --version

Expected Output

Docker version 27.5.1, build 9f9e405

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8.2 Docker Compose Version Check

docker compose version

Expected Output

Docker Compose version v2.32.4

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8.3 Docker System Information Check

docker info

Expected Output (key portions)

Client:
 Version:    27.5.1
 Context:    default

Server:
 Containers: 1
  Running: 0
  Paused: 0
  Stopped: 1
 Images: 1
 Server Version: 27.5.1
 Storage Driver: overlay2
 Operating System: Ubuntu 22.04.3 LTS
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 7.764GiB

Explanation

• Server Version: The Docker server version.
• CPUs, Total Memory: Resources available to Docker.
• Containers, Images: The number of containers and images currently on the system.

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8.4 hello-world Re-verification

docker run hello-world

Expected Output (key portion)

Hello from Docker!
This message shows that your installation appears to be working correctly.

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9. All-in-One Verification

Run the following command to check the installation status of all key tools at once.

echo "=== Docker ===" && docker --version && echo "" && \
echo "=== Docker Compose ===" && docker compose version && echo "" && \
echo "=== Docker Info (요약) ===" && docker info 2>/dev/null | grep -E "Server Version|CPUs|Total Memory|Operating System" && echo "" && \
echo "=== Docker Hub 로그인 상태 ===" && docker info 2>/dev/null | grep "Username" && echo "" && \
echo "=== hello-world 테스트 ===" && docker run --rm hello-world 2>&1 | head -n 5

Expected Output

=== Docker ===
Docker version 27.5.1, build 9f9e405

=== Docker Compose ===
Docker Compose version v2.32.4

=== Docker Info (요약) ===
 Server Version: 27.5.1
 Operating System: Ubuntu 22.04.3 LTS
 CPUs: 4
 Total Memory: 7.764GiB

=== Docker Hub 로그인 상태 ===
 Username: myuser

=== hello-world 테스트 ===

Hello from Docker!
This message shows that your installation appears to be working correctly.

If all items produce normal output, the container learning environment setup is complete.

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10. Common Issues and Solutions

10.1 Cannot connect to the Docker daemon

The Docker daemon is not running.

Windows/Mac: Verify that Docker Desktop is running. Check for the Docker icon in the system tray (taskbar).

Linux: Start the Docker service.

sudo systemctl start docker

Verification:

sudo systemctl status docker

Expected Output

● docker.service - Docker Application Container Engine
     Active: active (running) since ...

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10.2 permission denied while trying to connect to the Docker daemon socket

The current user is not a member of the docker group.

sudo usermod -aG docker $USER

You must log out and log back in or reboot after running this command.

After logging back in, verify:

groups

Expected Output

myuser adm sudo docker

If docker appears in the list, everything is correct.

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10.3 "WSL 2 installation is incomplete" When Launching Docker Desktop

A WSL2 kernel update is needed. In PowerShell (as administrator):

wsl --update

Expected Output

Checking for updates.
Updating Windows Subsystem for Linux...

After the update, launch Docker Desktop again.

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10.4 docker compose Command Not Found

The Docker Compose plugin is not installed.

sudo apt install docker-compose-plugin -y

After installation, verify:

docker compose version

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10.5 Docker Image Pull Is Very Slow

Docker Hub access may be slow depending on your network environment. You can configure a mirror registry in Docker Desktop.

In Settings > Docker Engine, add the following:

{
  "registry-mirrors": ["https://mirror.gcr.io"]
}

Click "Apply & Restart".

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10.6 Insufficient Disk Space

Docker images and containers can consume a lot of disk space. Clean up unused resources:

docker system df

Expected Output

TYPE            TOTAL     ACTIVE    SIZE      RECLAIMABLE
Images          5         1         2.3GB     1.8GB (78%)
Containers      3         0         15MB      15MB (100%)
Local Volumes   2         1         500MB     200MB (40%)
Build Cache     10        0         300MB     300MB

Cleanup command:

docker system prune

Expected Output

WARNING! This will remove:
  - all stopped containers
  - all networks not used by at least one container
  - all dangling images
  - unused build cache

Are you sure you want to continue? [y/N] y
Total reclaimed space: 2.1GB

Warning

docker system prune only deletes resources that are not in use. It does not affect running containers.

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11. Next Steps

Once the environment setup is complete, proceed to the next document: the Container Concepts Guide. Now that you have verified Docker is working correctly, you can learn about the basic concepts and operating principles of containers.

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