Image size and minimal base images in Docker - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a minimal base image in Docker?

A minimal base image is a very small Docker image that contains only the essential files needed to run applications. It helps reduce the overall image size and improves efficiency.

beginner

Why is keeping Docker image size small important?

Smaller Docker images use less disk space, download faster, and start containers quicker. This saves bandwidth and improves deployment speed.

intermediate

Name two popular minimal base images used in Docker.

Two popular minimal base images are Alpine Linux and BusyBox. Both are very small and commonly used to build lightweight containers.

intermediate

How can you reduce Docker image size when building your own image?

You can reduce image size by using minimal base images, removing unnecessary files, combining commands in one layer, and cleaning up package caches.

advanced

What is the trade-off when using very minimal base images like Alpine?

Minimal base images may lack some libraries or tools, so you might need to install extra packages. This can add complexity but keeps the image small.

Which of these is a minimal base image commonly used in Docker?

A Alpine

B Ubuntu Desktop

C Windows Server

D CentOS Full

Alpine is a very small Linux distribution often used as a minimal base image in Docker.

Why should you keep Docker images small?

A To save disk space and speed up downloads

B To make containers run slower

C To increase image complexity

D To use more bandwidth

Smaller images save disk space and download faster, improving deployment speed.

What is a common method to reduce Docker image size?

A Avoid cleaning package caches

B Use minimal base images

C Keep all build files inside the image

D Add more layers

Using minimal base images helps reduce the overall image size.

What might you need to do when using a minimal base image like Alpine?

A Use Windows commands

B Add a graphical user interface

C Increase image size intentionally

D Install missing libraries or tools

Minimal images may lack some tools, so you often install needed packages.

Which command helps reduce image layers in a Dockerfile?

A Use multiple RUN commands separately

B Add unnecessary files

C Combine multiple commands with && in one RUN

D Use COPY multiple times

Combining commands with && in one RUN reduces the number of layers and image size.

Explain what a minimal base image is and why it is useful in Docker.

Think about the smallest starting point for your container.

Describe at least three ways to reduce Docker image size when building your own images.

Focus on Dockerfile best practices and cleanup.