Image size and minimal base images in Docker - Mini Project: Build & Apply

Image size and minimal base images

📖 Scenario: You are working on a Docker project where keeping the image size small is important for faster downloads and efficient storage. You will create a Dockerfile using a minimal base image and add a simple file to it.

🎯 Goal: Build a Docker image using a minimal base image alpine and add a text file hello.txt with the content Hello, Docker!. Then display the image size using Docker commands.

📋 What You'll Learn

Create a Dockerfile starting with the alpine base image

Add a file named hello.txt with the exact content Hello, Docker!

Use a command to display the size of the built Docker image

💡 Why This Matters

🌍 Real World

Keeping Docker images small helps in faster deployment, less storage use, and quicker updates in real projects.

💼 Career

Understanding minimal base images and image size is essential for DevOps engineers to optimize containerized applications.

1

Create a minimal Dockerfile with alpine base

Create a file named Dockerfile with the first line exactly FROM alpine to use the minimal Alpine Linux base image.

Docker

# Your code here

Need a hint?

The first line in a Dockerfile specifies the base image. Alpine is a very small Linux image.

2

Add a text file with content

Add these two lines to the Dockerfile: RUN echo "Hello, Docker!" > /hello.txt to create the file inside the image.

Docker

FROM alpine
# Your code here

Need a hint?

Use the RUN command to execute shell commands inside the image during build.

3

Build the Docker image with a tag

Write the exact command to build the Docker image with tag hello-alpine using the current directory as context: docker build -t hello-alpine .

Docker

FROM alpine
RUN echo "Hello, Docker!" > /hello.txt
# Your code here

Need a hint?

The docker build command creates the image from the Dockerfile.

4

Display the size of the built image

Write the exact command to show the size of the image named hello-alpine: docker images hello-alpine --format "{{.Repository}}: {{.Size}}"

Docker

FROM alpine
RUN echo "Hello, Docker!" > /hello.txt
# Build command:
docker build -t hello-alpine .
# Your code here

Need a hint?

This command lists images filtered by name and shows their size in a simple format.