Development container patterns in Docker - Mini Project: Build & Apply

Development Container Patterns

📖 Scenario: You are working on a software project and want to create a development environment that is consistent for everyone on your team. Using a development container helps by packaging all the tools and dependencies inside a container.This project will guide you through creating a simple Dockerfile for a development container, adding configuration, running a command inside the container, and finally displaying the result.

🎯 Goal: Build a Docker development container that installs Python 3.12, sets a working directory, and runs a simple Python script inside the container.

📋 What You'll Learn

Create a Dockerfile with a base image of Python 3.12

Set the working directory inside the container to /app

Add a Python script named hello.py that prints 'Hello from container!'

Run the Python script inside the container and display the output

💡 Why This Matters

🌍 Real World

Development containers help teams work with the same tools and dependencies, avoiding the 'it works on my machine' problem.

💼 Career

Knowing how to create and use development containers is a key skill for DevOps engineers and developers to ensure consistent environments and smooth collaboration.

1

Create the Dockerfile with base image

Create a file named Dockerfile and write a line to use the base image python:3.12-slim.

Docker

# Create a Dockerfile with base image python:3.12-slim
# Your code here

Need a hint?

The first line in a Dockerfile usually starts with FROM followed by the base image name.

2

Set working directory and add Python script

In the Dockerfile, add a line to set the working directory to /app. Then create a file named hello.py with the exact content print('Hello from container!').

Docker

FROM python:3.12-slim
# Set working directory to /app
# Your code here

# Create hello.py file with print statement
# Your code here

Need a hint?

Use WORKDIR /app to set the directory inside the container. The Python script should have exactly one line printing the message.

3

Add command to run Python script

In the Dockerfile, add a line to run the Python script hello.py using the command python hello.py when the container starts.

Docker

FROM python:3.12-slim
WORKDIR /app

# Create hello.py file
RUN echo "print('Hello from container!')" > hello.py

# Add command to run python hello.py
# Your code here

Need a hint?

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

4

Build and run the container to see output

Build the Docker image with the tag dev-container and run it. Write the command to build the image and then the command to run the container so it prints Hello from container!.

Docker

FROM python:3.12-slim
WORKDIR /app

# Create hello.py file
RUN echo "print('Hello from container!')" > hello.py

CMD ["python", "hello.py"]

# Build the image
# Your code here

# Run the container
# Your code here

Need a hint?

Use docker build -t dev-container . to build and docker run --rm dev-container to run the container and see the output.