Choosing small base images (alpine, slim) in Docker - Mini Project: Build & Apply

Choosing Small Base Images with Docker

📖 Scenario: You are creating a Docker container for a simple Python application. To keep the container small and efficient, you want to choose a small base image.Small base images help your containers start faster and use less disk space, just like packing only the essentials for a trip instead of everything you own.

🎯 Goal: Build a Dockerfile that uses a small base image (python:3.12-alpine) to run a simple Python script.

📋 What You'll Learn

Create a Dockerfile starting with the python:3.12-alpine base image

Add a working directory /app

Copy a Python script named app.py into the container

Run the Python script using the CMD instruction

💡 Why This Matters

🌍 Real World

Small base images help developers create fast, efficient containers that use less disk space and bandwidth. This is important when deploying applications in the cloud or on limited resources.

💼 Career

Knowing how to choose and use small base images is a key skill for DevOps engineers and developers working with containerized applications.

1

Create the base Dockerfile with the alpine image

Create a Dockerfile that starts with the base image python:3.12-alpine using the FROM instruction.

Docker

# Your code here

Need a hint?

Use the FROM keyword followed by python:3.12-alpine to specify the base image.

2

Set the working directory and copy the Python script

Add a WORKDIR instruction to set the working directory to /app. Then add a COPY instruction to copy app.py from your local folder to the container's /app directory.

Docker

FROM python:3.12-alpine
# Your code here

Need a hint?

Use WORKDIR /app to set the folder inside the container. Use COPY app.py /app/ to copy the file.

3

Add the command to run the Python script

Add a CMD instruction to run the Python script app.py using python.

Docker

FROM python:3.12-alpine
WORKDIR /app
COPY app.py /app/
# Your code here

Need a hint?

Use CMD ["python", "app.py"] to run the script when the container starts.

4

Build and run the Docker container

Write the command to build the Docker image named small-python-app from the current directory. Then write the command to run the container from this image.

Docker

FROM python:3.12-alpine
WORKDIR /app
COPY app.py /app/
CMD ["python", "app.py"]
# Your code here

Need a hint?

Use docker build -t small-python-app . to build and docker run small-python-app to run.