How it works...

The preceding pip3 install command, whether it is executed explicitly in a virtual environment or during the build process for a Docker container, downloads and installs all of your project dependencies from requirements/base.txt and requirements/dev.txt. As you can see, you can specify a version of the module that you need for the Django framework and even directly install from a specific commit at the Git repository, as done for social-app-django in our example.

When you have many dependencies in your project, it is good practice to stick to a narrow range of release versions for Python module release versions. Then you can have greater confidence that the project integrity will not be broken due to updates in your dependencies, which might contain conflicts or backward incompatibility. This is particularly important when deploying your project or handing it off to a new developer.

If you have already manually installed the project requirements with pip one by one, you can generate the requirements/base.txt file using the following command within your virtual environment:

(myproject_env)$ pip3 freeze > requirements/base.txt

The same can be executed within the Docker app container, as in the following:

myproject_docker/$ docker exec -it myproject_docker_app_1 \
> /bin/bash
root:/usr/src/app# pip3 freeze > requirements/base.txt