Installing Docker - Quick Revision & Summary

Recall & Review

beginner

What is Docker?

Docker is a tool that lets you package and run applications in isolated containers, making it easy to move and run software anywhere.

beginner

Which command updates the package list on Ubuntu before installing Docker?

The command is sudo apt-get update. It refreshes the list of available packages.

intermediate

Why do we add Docker’s official GPG key during installation?

Adding the GPG key ensures the packages you download are authentic and safe to install.

beginner

What is the purpose of the command sudo apt-get install docker-ce docker-ce-cli containerd.io?

This command installs Docker Engine, the command line interface, and the container runtime needed to run containers.

beginner

How can you verify Docker is installed and running correctly?

Run sudo docker run hello-world. It downloads a test image and runs it, showing a success message if all is well.

What is the first step to install Docker on Ubuntu?

A Update the package list with <code>sudo apt-get update</code>

B Install Docker directly with <code>sudo apt-get install docker</code>

C Run <code>docker run hello-world</code>

D Add Docker’s GPG key

Updating the package list ensures you get the latest package information before installing Docker.

Why do you add Docker’s official repository before installing Docker?

A To update the system kernel

B To get the latest Docker packages from Docker’s source

C To remove old Docker versions

D To install Docker Compose

Adding Docker’s repository lets you install the latest Docker versions maintained by Docker.

Which command installs Docker Engine and related tools on Ubuntu?

A sudo apt-get install docker-ce docker-ce-cli containerd.io

B sudo docker install engine

C apt-get install docker

D docker setup install

This command installs Docker Engine, CLI, and container runtime needed to run containers.

What does the command sudo docker run hello-world do?

A Removes Docker containers

B Installs Docker

C Updates Docker to the latest version

D Runs a test container to verify Docker installation

It runs a small test container that prints a success message if Docker is working.

Which of these is NOT a required step to install Docker on Ubuntu?

A Installing Docker Engine

B Updating package list

C Running <code>docker-compose up</code> before installation

D Adding Docker’s GPG key

Running docker-compose up is for running containers, not part of Docker installation.

Describe the main steps to install Docker on an Ubuntu system.

Think about preparing the system, adding trusted sources, installing, and testing.

Explain why verifying Docker installation with sudo docker run hello-world is important.

Why test after installing software?

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