Why container security matters in Docker - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the command to list all running Docker containers.

Docker

docker [1]

Drag options to blanks, or click blank then click option'

Arun

Bimages

Cbuild

Dps

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'docker run' instead of 'docker ps' to list containers.

Using 'docker images' which lists images, not containers.

The docker ps command shows all running containers.

2fill in blank

medium

Complete the command to remove a Docker container by its ID.

Docker

docker [1] container_id

Drag options to blanks, or click blank then click option'

Arm

Bstop

Crun

Dexec

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'docker stop' which only stops but does not remove containers.

Using 'docker exec' which runs commands inside containers.

The docker rm command removes a container by its ID.

3fill in blank

hard

Fix the error in the command to build a Docker image from a Dockerfile.

Docker

docker build -t [1] .

Drag options to blanks, or click blank then click option'

Amy_image

B-f

Crun

Dcontainer

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-f' after '-t' which is incorrect here.

Using 'run' or 'container' which are not valid image names.

The -t option tags the image with a name like my_image.

4fill in blank

hard

Fill both blanks to create a Docker container with a specific name and run it in detached mode.

Docker

docker run -d --name [1] [2]

Drag options to blanks, or click blank then click option'

Amy_container

Bnginx

C-p 80:80

Dubuntu

Attempts:

3 left

💡 Hint

Common Mistakes

Putting image name in the container name blank.

Using port mapping instead of image name.

my_container is the container name, and nginx is the image to run.

5fill in blank

hard

Fill all three blanks to write a Dockerfile snippet that sets the base image, copies files, and runs a command.

Docker

FROM [1]
COPY . /app
CMD ["[2]", "[3]"]

Drag options to blanks, or click blank then click option'

Apython:3.12-slim

Bpython

Capp.py

Dnginx

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'nginx' as base image for a Python app.

Swapping command and script names.

The base image is python:3.12-slim, the command is python, and the script to run is app.py.

Practice

1. Why is container security important in software development?

easy

A. It automatically updates the container software.

B. It makes containers run faster on any machine.

C. It protects applications and data from unauthorized access and attacks.

D. It reduces the size of container images.

Solution

1. Step 1: Understand container security purpose

   Container security aims to protect apps and data inside containers from threats.

2. Step 2: Compare options with security goals

   Only protecting apps and data matches the goal of container security.

3. Final Answer:

   It protects applications and data from unauthorized access and attacks. -> Option C

4. Quick Check:

   Container security = Protect apps and data [OK]

Hint: Security means protection from attacks, not performance [OK]

Common Mistakes:

• Confusing security with performance improvements
• Thinking security automatically updates containers
• Believing security reduces image size

2. Which Docker command helps scan images for security vulnerabilities?

easy

A. docker scan <image_name>

B. docker build <image_name>

C. docker run <image_name>

D. docker push <image_name>

Solution

1. Step 1: Identify scanning command

   Docker provides docker scan to check images for vulnerabilities.

2. Step 2: Eliminate other commands

   docker build creates images, docker run runs containers, docker push uploads images; none scan security.

3. Final Answer:

   docker scan <image_name> -> Option A

4. Quick Check:

   Scan command = docker scan [OK]

Hint: Scan images with 'docker scan' command [OK]

Common Mistakes:

• Using build or run commands to scan images
• Confusing push with scanning
• Not knowing 'docker scan' exists

3. What is the output of this command if the image has no vulnerabilities?

docker scan alpine

medium

A. Error: image not found

B. Scan skipped due to permissions

C. Vulnerabilities detected: 5

D. No vulnerabilities found

Solution

1. Step 1: Understand docker scan output

   If no security issues exist, the scan reports no vulnerabilities found.

2. Step 2: Match output to options

   Only No vulnerabilities found states no vulnerabilities, others indicate errors or issues.

3. Final Answer:

   No vulnerabilities found -> Option D

4. Quick Check:

   No vulnerabilities = 'No vulnerabilities found' [OK]

Hint: No issues means 'No vulnerabilities found' message [OK]

Common Mistakes:

• Assuming scan always finds vulnerabilities
• Confusing error messages with scan results
• Ignoring permission-related errors

4. You run docker scan myapp but get a permission error. What should you do to fix it?

medium

A. Run the command with sudo or as an admin user

B. Rebuild the image with docker build

C. Delete the image and pull it again

D. Restart the Docker service

Solution

1. Step 1: Identify cause of permission error

   Permission errors usually mean the user lacks rights to run the scan.

2. Step 2: Fix permission by running with elevated rights

   Using sudo or admin rights allows the scan to run properly.

3. Final Answer:

   Run the command with sudo or as an admin user -> Option A

4. Quick Check:

   Permission error = use sudo/admin [OK]

Hint: Permission errors often need sudo/admin rights [OK]

Common Mistakes:

• Rebuilding image does not fix permissions
• Deleting image unrelated to permission issues
• Restarting Docker service won't fix user rights

5. Which practice best improves container security in a production environment?

hard

A. Running containers with root user for easier access

B. Regularly scanning images and using minimal base images

C. Disabling all network restrictions for faster communication

D. Using large images with many tools installed

Solution

1. Step 1: Identify best security practices

   Regular scanning finds vulnerabilities early; minimal base images reduce attack surface.

2. Step 2: Evaluate other options

   Running as root, disabling network restrictions, or using large images increase risks.

3. Final Answer:

   Regularly scanning images and using minimal base images -> Option B

4. Quick Check:

   Best security = scan + minimal images [OK]

Hint: Scan often and keep images small and simple [OK]

Common Mistakes:

• Running containers as root user
• Disabling network restrictions
• Using large, tool-heavy images