Installing Docker - Try It Yourself

Installing Docker

📖 Scenario: You are setting up a new development environment on your computer. To work with containers, you need to install Docker, a tool that helps you run applications easily inside containers.

🎯 Goal: Learn how to install Docker on your system using command line instructions step-by-step.

📋 What You'll Learn

Use the official Docker installation commands for Ubuntu Linux

Add the Docker repository to your system

Install Docker Engine

Verify Docker installation by checking its version

💡 Why This Matters

🌍 Real World

Installing Docker is the first step to using containers for developing, testing, and deploying applications easily.

💼 Career

Many DevOps and software development roles require Docker knowledge to manage containerized applications.

1

Update package index

Run the command sudo apt-get update to update the package index on your Ubuntu system.

Docker

# Run the command to update package index
# Your code here

Hint

Updating package index helps your system know about the latest available packages.

2

Install prerequisite packages

Run the command sudo apt-get install ca-certificates curl gnupg to install packages needed to add Docker's official GPG key.

Docker

sudo apt-get update
# Install prerequisite packages
# Your code here

Hint

These packages help your system securely download and verify Docker packages.

3

Add Docker's official GPG key and repository

Run these commands to add Docker's official GPG key and repository: sudo mkdir -p /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, and echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null.

Docker

sudo apt-get update
sudo apt-get install ca-certificates curl gnupg
# Add Docker's GPG key and repository
# Your code here

Hint

Adding the GPG key and repository lets your system trust and find Docker packages.

4

Install Docker Engine and verify

Run sudo apt-get update again to refresh package index, then install Docker Engine with sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin. Finally, verify installation by running sudo docker --version.

Docker

sudo apt-get update
sudo apt-get install ca-certificates curl gnupg
sudo mkdir -p /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
echo "deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.gpg] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable" | sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
# Update package index again
# Install Docker Engine packages
# Verify Docker installation
# Your code here

Hint

Installing Docker Engine lets you run containers. Checking the version confirms success.

Practice

1. What is the main purpose of installing Docker on your computer?

easy

A. To create spreadsheets

B. To edit text files

C. To run applications inside containers

D. To browse the internet

Solution

1. Step 1: Understand Docker's role

   Docker is a tool that allows running applications inside isolated containers.

2. Step 2: Compare options

   Only To run applications inside containers describes running apps in containers, which is Docker's main use.

3. Final Answer:

   To run applications inside containers -> Option C

4. Quick Check:

   Docker runs apps in containers = D [OK]

Hint: Docker runs apps in containers, not for editing or browsing [OK]

Common Mistakes:

• Confusing Docker with text editors or browsers
• Thinking Docker is for general software installation
• Assuming Docker manages spreadsheets

2. Which command correctly checks the installed Docker version after installation?

easy

A. version docker --check

B. docker version check

C. check docker version

D. docker --version

Solution

1. Step 1: Recall Docker version command syntax

   The correct command to check Docker version is docker --version.

2. Step 2: Eliminate incorrect syntax

   Other options do not follow Docker CLI syntax and will cause errors.

3. Final Answer:

   docker --version -> Option D

4. Quick Check:

   Correct Docker version command = A [OK]

Hint: Use 'docker --version' to check Docker version quickly [OK]

Common Mistakes:

• Using incorrect command order or words
• Omitting double dashes before 'version'
• Trying non-Docker commands to check version

3. After running docker --version, you see this output:

Docker version 24.0.2, build cb74dfc

What does this output tell you?

medium

A. Docker is installed and working

B. Docker is not installed

C. Docker installation failed

D. Docker needs to be updated

Solution

1. Step 1: Interpret the version output

   The output shows Docker's version number and build info, meaning Docker is installed.

2. Step 2: Understand what output means

   If Docker was not installed or failed, the command would error or show no version.

3. Final Answer:

   Docker is installed and working -> Option A

4. Quick Check:

   Version output means Docker works = C [OK]

Hint: Version output means Docker installed correctly [OK]

Common Mistakes:

• Thinking version output means failure
• Confusing version info with error messages
• Assuming update needed without checking latest version

4. You tried to install Docker on Ubuntu with sudo apt install docker but got an error. What is the likely fix?

medium

A. Use sudo apt install docker.io instead

B. Run docker --version again

C. Restart the computer and try again

D. Install Docker using yum command

Solution

1. Step 1: Understand Ubuntu package naming

   On Ubuntu, the Docker package is named docker.io, not just docker.

2. Step 2: Correct the install command

   Using sudo apt install docker.io installs Docker properly on Ubuntu.

3. Final Answer:

   Use sudo apt install docker.io instead -> Option A

4. Quick Check:

   Ubuntu Docker package = docker.io = A [OK]

Hint: Ubuntu Docker package is 'docker.io', not 'docker' [OK]

Common Mistakes:

• Trying to install 'docker' package which doesn't exist
• Using wrong package manager commands
• Ignoring error messages without checking package name

5. You want to install Docker on Windows using the official installer. Which step should you do first?

medium

A. Run sudo apt install docker in PowerShell

B. Download Docker Desktop from the official Docker website

C. Open Command Prompt and type docker run

D. Install VirtualBox before Docker

Solution

1. Step 1: Identify Windows installation method

   Windows users install Docker using Docker Desktop downloaded from Docker's official site.

2. Step 2: Eliminate incorrect steps

   Linux commands like sudo apt install don't work on Windows; VirtualBox is not required.

3. Final Answer:

   Download Docker Desktop from the official Docker website -> Option B

4. Quick Check:

   Windows Docker install starts with official Docker Desktop download = B [OK]

Hint: Windows Docker install starts with official Docker Desktop download [OK]

Common Mistakes:

• Trying Linux commands on Windows
• Assuming VirtualBox is needed for Docker
• Running Docker commands before installation