Why image optimization matters in Docker - See It in Action

Why Image Optimization Matters

📖 Scenario: You are working on a web application that needs to be deployed using Docker containers. The application image is currently very large, which causes slow downloads and uses a lot of storage space on servers.Optimizing Docker images can make your deployments faster and save resources.

🎯 Goal: Learn how to create a simple Dockerfile and then optimize the Docker image size by using a smaller base image and cleaning up unnecessary files.

📋 What You'll Learn

Create a Dockerfile with a base image and a simple command

Add a variable to specify the base image version

Modify the Dockerfile to use a smaller base image and remove unnecessary files

Build and display the size of the Docker image

💡 Why This Matters

🌍 Real World

Optimizing Docker images helps reduce download times and storage use when deploying applications in real environments.

💼 Career

Knowing how to optimize container images is a key skill for DevOps engineers to improve deployment efficiency and resource management.

1

Create a basic Dockerfile

Create a file named Dockerfile with the following content exactly:
FROM python:3.12-slim
CMD ["python3", "--version"]

Docker

# Create a Dockerfile with FROM python:3.12-slim and CMD ["python3", "--version"]
# Your code here

Need a hint?

Use the FROM instruction to specify the base image and CMD to run the command.

2

Add a base image version variable

Add a build argument named PYTHON_VERSION with value 3.12-slim and use it in the FROM line like this:
ARG PYTHON_VERSION=3.12-slim
FROM python:${PYTHON_VERSION}

Docker

FROM python:3.12-slim
CMD ["python3", "--version"]
# Add ARG PYTHON_VERSION=3.12-slim and use it in FROM line
# Your code here

Need a hint?

Use ARG to define a variable and then use ${VAR_NAME} syntax in FROM.

3

Optimize the Dockerfile

Change the base image to python:3.12-alpine by setting PYTHON_VERSION=3.12-alpine and add a RUN command to remove cache files:
RUN rm -rf /var/cache/apk/*

Docker

ARG PYTHON_VERSION=3.12-slim
FROM python:${PYTHON_VERSION}
CMD ["python3", "--version"]
# Change PYTHON_VERSION to 3.12-alpine and add RUN rm -rf /var/cache/apk/*
# Your code here

Need a hint?

Use the Alpine base image for smaller size and clean cache files to reduce image size.

4

Build and show the Docker image size

Build the Docker image with tag optimized-python and then run docker images optimized-python --format "{{.Repository}}: {{.Size}}" to display the image size.

Docker

# Build the image with tag optimized-python
# Then run docker images optimized-python --format "{{.Repository}}: {{.Size}}" to show size
# Your code here

Need a hint?

Use docker build -t optimized-python . to build and docker images to check size.