Reducing image size strategies in Docker - Mini Project: Build & Apply

Reducing image size strategies

📖 Scenario: You are working on a Docker project where the image size is too large. Large images take longer to download and use more storage. You want to learn how to reduce the size of your Docker images by using best practices.

🎯 Goal: Build a simple Dockerfile that uses a small base image, installs only necessary packages, and cleans up temporary files to reduce the final image size.

📋 What You'll Learn

Use the alpine base image for a small starting point

Install the curl package using apk

Remove cache files after installation to keep the image small

Print a message when the container runs

💡 Why This Matters

🌍 Real World

Developers often need to create Docker images that are small to speed up deployment and reduce storage costs.

💼 Career

Knowing how to reduce Docker image size is a valuable skill for DevOps engineers and developers working with containers.

1

Create a Dockerfile with a small base image

Create a file named Dockerfile and write the first line to use the alpine:latest image as the base image with FROM alpine:latest.

Docker

# Write the base image line
# Your code here

Need a hint?

The alpine image is very small and good for reducing image size.

2

Install curl package with cleanup

Add a line to the Dockerfile to install the curl package using apk add --no-cache curl. This installs curl without cache files to keep the image small.

Docker

FROM alpine:latest
# Add a line to install curl without cache
# Your code here

Need a hint?

Use apk add --no-cache to avoid storing cache files in the image.

3

Add a command to print a message

Add a line to the Dockerfile to run echo "Hello from small image!" when the container starts using CMD.

Docker

FROM alpine:latest
RUN apk add --no-cache curl
# Add a CMD line to print a message
# Your code here

Need a hint?

The CMD instruction defines the default command to run when the container starts.

4

Build and run the Docker image

Build the Docker image with the tag small-image using docker build -t small-image .. Then run the container with docker run small-image to see the message.

Docker

FROM alpine:latest
RUN apk add --no-cache curl
CMD ["echo", "Hello from small image!"]
# Build and run commands are run in terminal, not in Dockerfile

Need a hint?

Use your terminal to run the build and run commands. The output should show the message.