Docker containerization in FastAPI - Mini Project: Build & Apply

Docker containerization

📖 Scenario: You want to share your FastAPI web app easily with others or deploy it on any computer without setup hassle. Docker helps by packaging your app and its environment into a container.

🎯 Goal: Build a simple FastAPI app and create a Docker container to run it anywhere.

📋 What You'll Learn

Create a basic FastAPI app with one route

Add a variable for the port number

Write a Dockerfile to containerize the app

Run the app inside the Docker container

💡 Why This Matters

🌍 Real World

Docker containerization lets developers package their web apps with all dependencies so they run the same everywhere, avoiding setup issues.

💼 Career

Knowing how to containerize apps with Docker is essential for modern backend development, deployment pipelines, and cloud services.

1

Create a basic FastAPI app

Create a file called main.py with a FastAPI app named app. Add a route / that returns a dictionary with {"message": "Hello, Docker!"}.

FastAPI

# Your code here

Need a hint?

Import FastAPI, create app = FastAPI(), then define an async function with @app.get("/") decorator returning the dictionary.

2

Add a port configuration variable

In main.py, add a variable called PORT and set it to 8000.

FastAPI

from fastapi import FastAPI

app = FastAPI()

PORT = 8000

@app.get("/")
async def read_root():
    return {"message": "Hello, Docker!"}

# Your code here

Need a hint?

Just add PORT = 8000 anywhere in main.py.

3

Write a Dockerfile to containerize the app

Create a Dockerfile with these lines exactly: FROM python:3.12-slim, WORKDIR /app, COPY . /app, RUN pip install fastapi uvicorn, and CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"].

FastAPI

from fastapi import FastAPI

app = FastAPI()

PORT = 8000

@app.get("/")
async def read_root():
    return {"message": "Hello, Docker!"}

# Create Dockerfile with required lines

Need a hint?

Write a Dockerfile with the exact lines to set up Python, copy files, install packages, and run the app with uvicorn.

4

Run the app inside the Docker container

Add a docker-compose.yml file with a service named fastapi-app that builds from the current directory, maps port 8000 on the host to 8000 in the container, and restarts always.

FastAPI

from fastapi import FastAPI

app = FastAPI()

PORT = 8000

@app.get("/")
async def read_root():
    return {"message": "Hello, Docker!"}

# Dockerfile content:
# FROM python:3.12-slim
# WORKDIR /app
# COPY . /app
# RUN pip install fastapi uvicorn
# CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]

# Create docker-compose.yml with fastapi-app service
# Your code here

Need a hint?

Write a docker-compose.yml file with a service named fastapi-app that builds the Dockerfile, maps port 8000, and restarts automatically.