Setting up Docker

As our application grows into having multiple layers, such as a database, coupling the application into a single piece enables us to deploy our application. We’ll be using Docker to containerize our application layers into a single image, which can then be easily deployed locally or in the cloud.

Additionally, using a Dockerfile and a docker-compose file eliminates the need to upload and share images of our applications. New versions of our applications can be built from the Dockerfile and deployed using the docker-compose file. Application images can also be stored and retrieved from Docker Hub. This is known as a push and pull operation.

To begin setting up, download and install Docker from https://docs.docker.com/install.

Dockerfile

A Dockerfile contains instructions on how our application image is to be built. The following is an example Dockerfile:

FROM PYTHON:3.8
# Set working directory to /usr/src/app
WORKDIR /usr/src/app
# Copy the contents of the current local directory into the container's working directory
ADD . /usr/src/app
# Run a command
CMD ["python", "hello.py"]

Next, we’ll build the application container image and tag it getting_started as follows:

$ docker build -t getting_started .

If the Dockerfile isn’t present in the directory where the command is being run, the path to the Dockerfile should be properly appended as follows:

$ docker build -t api api/Dockerfile

The container image can be run using the following command:

$ docker run getting-started

Docker is an efficient tool for containerization. We have only looked at the basic operations and we’ll learn more operations practically in Chapter 9, Deploying FastAPI Applications.