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Containerization with Docker

FastAPI has been a game-changer in the world of Python web frameworks, but deploying it can be a bit complex. One of the best ways to get around the deployment complexity is to use Docker. Docker is a containerization platform that lets you package your application along with all of its dependencies into a single unit, called a container, that can be run on any machine that has Docker installed.

What is Docker?​

Docker is a platform that allows developers to package applications into containers. A container is a standalone unit that contains everything needed to run an application. This includes the application itself, as well as all of its dependencies.

Containers are lightweight and fast, and they ensure that your application will run the same way on any machine, regardless of the host operating system.

Dockerizing FastAPI Application​

To begin, you need to have Docker installed on your machine. If you don't have Docker installed, you can download and install it from the Docker website.

Once you have Docker installed, the next step is to create a Dockerfile. A Dockerfile is a script that contains instructions on how to build a Docker image for your application.

Here's a basic example of a Dockerfile for a FastAPI application:

FROM python:3.9

WORKDIR /app

COPY requirements.txt ./
RUN pip install --no-cache-dir -r requirements.txt

COPY . .

CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "80"]

This Dockerfile does the following:

  • It starts from a base image python:3.9.
  • It sets the working directory in the container to /app.
  • It copies the requirements.txt file from your current directory to the current directory in the container.
  • It runs the command pip install --no-cache-dir -r requirements.txt to install the dependencies of your application.
  • It copies the rest of your application code to the container.
  • Finally, it sets the command that will be run when the container starts.

Next, we need to build the Docker image using the docker build command. 

docker build -t my-fastapi-app .

Here, -t my-fastapi-app specifies the name of the Docker image, and . specifies the build context, which is the current directory.

Finally, run the Docker container with the docker run command.

docker run -d -p 80:80 my-fastapi-app

In this command, -d means that the container will run in the background, -p 80:80 maps port 80 in the container to port 80 on your machine, and my-fastapi-app is the name of the Docker image.

Now, you can open your browser and navigate to http://localhost to see your FastAPI application running in a Docker container!

Conclusion​

Dockerizing your FastAPI application ensures that your application runs the same way in every environment, making the deployment process much smoother. Plus, Docker is a widely-used platform, meaning that you'll find plenty of resources and community support. Happy coding!