How to Dockerize a FastAPI Application

In this blog post we will create a dockerized FastAPI app.

In the root folder of your project create a requirements.txt file. This file will contain the packages that we need for our app. In this case, we need three applications: FastAPI, Pydantic (used for data validation) and Uvicorn (a web server). Our requirements file will look like this:

fastapi>=0.115.4
pydantic>=2.9.2
uvicorn[standard]>=0.32.0

Now create in the root directory of your project a directory called app and in that directory create a blank file called __init__.py (used for telling Python of the existence of submodules in the directory) and another file called main.py. In main.py add the following lines of code:

from fastapi import FastAPI

app = FastAPI()


@app.get('/')
def hello_world():
    return "Hello World"

Save the file and exit.

We then create our Dockerfile called Dockerfile in the root directory of our project folder and add the following lines:

# Pull the Python 3.13 image from Docker Hub
FROM python:3.13

# Set the working directory in the Docker container as /code
WORKDIR /code

# Copy the requirements.txt file from the host (our machine) to /code/requirements.txt in the Docker container
COPY ./requirements.txt /code/requirements.txt

# Install the latest version of pip (Python package manager) and do not use the cache (i.e. fetch it from the server)
RUN pip install --no-cache-dir --upgrade pip

# Install the Python packages in the requirements file and do not use the cache
RUN pip install --no-cache-dir --upgrade -r /code/requirements.txt

# Copy our application files from the host (our machine) to /code/app in the Docker container
COPY ./app /code/app

# Run uvicorn loading the main.py file and use the options below.  Add --proxy-headers if running behind a proxy like nginx
CMD ["uvicorn", "app.main:app", "--host", "0.0.0.0", "--port", "8000", "--proxy-headers"]

Save and exit. Build the Docker container using the following command:

docker build -t my-python-app .

In the above command we are telling Docker to build our container using the tag name my-python-app and the location of our our Dockerfile which is in the current directory, denoted by ..

We can now run our container using the following command:

docker run -d --name my-python-app -p 8000:8000 my-python-app

In the above command we tell Docker to run detached (-d), the name of our container (my-python-app), the port (host port 8000) and (container port 8000), and the name of the image (my-python-app).