development.md

FastAPI Project - Development

Docker Compose

• Start the local stack with Docker Compose:

docker compose watch

• Now you can open your browser and interact with these URLs:

Backend, JSON based web API based on OpenAPI: http://localhost:8001

Automatic interactive documentation with Swagger UI (from the OpenAPI backend): http://localhost:8001/docs

Note: The first time you start your stack, it might take a minute for it to be ready. While the backend waits for the database to be ready and configures everything. You can check the logs to monitor it.

To check the logs, run (in another terminal):

docker compose logs

To check the logs of a specific service, add the name of the service, e.g.:

docker compose logs backend

Local Development

The Docker Compose files are configured so that each of the services is available in a different port in localhost.

For the backend, Docker maps container port 8000 to host port 8001, so the backend is at http://localhost:8001.

This way, you could turn off a Docker Compose service and start its local development service, and everything would keep working, because it all uses the same ports.

For example, you can stop that backend service in the Docker Compose, in another terminal, run:

docker compose stop backend

And then you can run the local development server for the backend:

cd backend
fastapi dev app/main.py --port 8001

Docker Compose files and env vars

There is a main docker-compose.yml file with all the configurations that apply to the whole stack, it is used automatically by docker compose.

These Docker Compose files use the .env file containing configurations to be injected as environment variables in the containers.

They also use some additional configurations taken from environment variables set in the scripts before calling the docker compose command.

After changing variables, make sure you restart the stack:

docker compose watch

The .env file

The .env file is the one that contains all your configurations, generated keys and passwords, etc.

Depending on your workflow, you could want to exclude it from Git, for example if your project is public. In that case, you would have to make sure to set up a way for your CI tools to obtain it while building or deploying your project.

One way to do it could be to add each environment variable to your CI/CD system, and updating the docker-compose.yml file to read that specific env var instead of reading the .env file.

Pre-commits and code linting

we are using a tool called pre-commit for code linting and formatting.

When you install it, it runs right before making a commit in git. This way it ensures that the code is consistent and formatted even before it is committed.

You can find a file .pre-commit-config.yaml with configurations at the root of the project.

Install pre-commit to run automatically

pre-commit is already part of the dependencies of the project, but you could also install it globally if you prefer to, following the official pre-commit docs.

After having the pre-commit tool installed and available, you need to "install" it in the local repository, so that it runs automatically before each commit.

Using uv, you could do it with:

❯ uv run pre-commit install
pre-commit installed at .git/hooks/pre-commit

Now whenever you try to commit, e.g. with:

git commit

...pre-commit will run and check and format the code you are about to commit, and will ask you to add that code (stage it) with git again before committing.

Then you can git add the modified/fixed files again and now you can commit.

Running pre-commit hooks manually

you can also run pre-commit manually on all the files, you can do it using uv with:

❯ uv run pre-commit run --all-files
check for added large files..............................................Passed
check toml...............................................................Passed
check yaml...............................................................Passed
ruff.....................................................................Passed
ruff-format..............................................................Passed
eslint...................................................................Passed
prettier.................................................................Passed

URLs

The production or staging URLs would use these same paths, but with your own domain.

Development URLs

Development URLs, for local development.

Backend: http://localhost:8001

Automatic Interactive Docs (Swagger UI): http://localhost:8001/docs

Automatic Alternative Docs (ReDoc): http://localhost:8001/redoc