Using .dockerignore - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of a .dockerignore file?

A .dockerignore file tells Docker which files and folders to ignore when building an image. This helps make builds faster and smaller by excluding unnecessary files.

beginner

How do you write a pattern in .dockerignore to ignore all .log files?

You write *.log in the .dockerignore file to ignore all files ending with .log.

beginner

True or False: Files listed in .dockerignore are still available on your local machine after the Docker build.

True. The .dockerignore file only affects what files are sent to the Docker build context. It does not delete or change files on your local machine.

beginner

What happens if you do not use a .dockerignore file in your Docker project?

Docker will send all files in the build folder to the Docker daemon. This can make builds slower and images larger because unnecessary files are included.

beginner

How can you ignore a folder named temp using .dockerignore?

Add temp/ to the .dockerignore file to ignore the entire temp folder and its contents.

What does the .dockerignore file control?

A Which files are sent to the Docker build context

B Which files are deleted after build

C Which files are copied into the container at runtime

D Which files are executed inside the container

The .dockerignore file controls which files and folders are excluded from the build context sent to Docker during image build.

Which pattern in .dockerignore ignores all files in the logs folder?

A logs

B *.logs

C logs/

D /logs

Adding logs/ ignores the entire logs folder and its contents.

If you want to ignore all files named secret.txt anywhere in the project, what pattern should you use?

A */secret.txt

B secret.txt

C **/secret.txt

D secret.txt/

Simply writing secret.txt ignores all files with that exact name anywhere in the build context.

What is the effect of ignoring files with .dockerignore on the final Docker image size?

A It reduces the image size by excluding unnecessary files

B It increases the image size

C It has no effect on image size

D It deletes files from the image after build

Ignoring files reduces the build context size, so fewer files are copied into the image, making it smaller.

Which of these files is commonly included in .dockerignore to speed up builds?

A app.py

B Dockerfile

C README.md

D node_modules

Folders like node_modules are often large and not needed in the build context, so they are ignored.

Explain what a .dockerignore file does and why it is useful in Docker projects.

Think about how sending fewer files to Docker helps.

Describe how you would write patterns in .dockerignore to ignore a folder and all files with a certain extension.

Consider ignoring a folder named 'temp' and all '.log' files.