Description

This is a minimalistic and extensible FastAPI template that incorporates factory pattern architecture with divisional folder structure. It's suitable for developing small to medium sized API oriented micro-services. The architecture is similar to what you'd get with Flask's Blueprint.

Features

• It uses FastAPI framework for API development. FastAPI is a modern, highly performant, web framework for building APIs with Python 3.6+.

• The APIs are served with Uvicorn server. Uvicorn is a lightning-fast "ASGI" server. It runs asynchronous Python web code in a single process.

• Gunicorn is used here to manage Uvicorn and run multiple of these concurrent processes. That way, you get the best of concurrency and parallelism.

• OAuth2 (with hashed password and Bearer with JWT) based authentication

• CORS (Cross Origin Resource Sharing) enabled.

• Flask inspired divisional folder structure better decoupling and encapsulation. This is suitable for small to medium backend development.

• Dockerized using uvicorn-gunicorn-fastapi-docker. This image will set a sensible configuration based on the server it is running on (the amount of CPU cores available) without making sacrifices.

  It has sensible defaults, but you can configure it with environment variables or override the configuration files.

Quickstart

Spin Up the Cookiecutter

• Install cookiecutter.

• Go to your project folder and run:

  cookiecutter https://github.com/rednafi/fastapi-nano.git

• Follow the prompts to generate your project.

  repo [fastapi-nano]:
  api_a [api_a]:
  api_b [api_b]:
  year [2020]:
  fname [Redowan Delowar]:
  email [[email protected]]:
  

Run the Containers

• Go to your template folder and run:

  docker-compose up -d

Check the APIs

• To play around with the APIs, go to the following link on your browser:

  http://localhost:5000/docs
  

  This will take you to an UI like below:

  

• Press the authorize button on the right and add username and password. The APIs use OAuth2 (with hashed password and Bearer with JWT) based authentication. In this case, the username and password is ubuntu and debian respectively.

  

  Clicking the authorize button will bring up a screen like this:

  

• Then select any of the api_a or api_b APIs and put an integer in the number box and click the authorize button.

  

• Hitting the API should give a json response with random integers.

  

• Also, notice the curl section in the above screen shot. You can directly use the highlighted curl command in your terminal.

  curl -X GET "http://localhost:5000/api_a/22" -H "accept: application/json" -H "Authorization: Bearer eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJzdWIiOiJ1YnVudHUiLCJleHAiOjY4NDg3NDI1MDl9.varo-uXei0kmGkejkfzCtOkWvW6y7ewzaKBj4qZZHWQ"

  This should show a response like this:

  {
  "seed": 22,
  "random_first": 5,
  "random_second": 13
  }

• To test the GET APIs with Python, you can use a http client library like httpx:

  import httpx
  
  token = (
      "eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9."
      + "eyJzdWIiOiJ1YnVudHUiLCJleHAiOjY4NDg3NDI1MDl9."
      + "varo-uXei0kmGkejkfzCtOkWvW6y7ewzaKBj4qZZHWQ"
  )
  
  headers = {
      "accept": "application/json",
      "Authorization": f"Bearer {token}",
  }
  
  with httpx.Client() as client:
      response = client.get("http://localhost:5000/api_a/22", headers=headers)
      print(response.json())

Folder Structure

This shows the folder structure of the default template.

fastapi-nano
├── app                                 # primary application folder
│   ├── apis                            # this houses all the API packages
│   │   ├── api_a                       # api_a package
│   │   │   ├── __init__.py             # empty init file to make the api_a folder a package
│   │   │   ├── mainmod.py              # main module of api_a package
│   │   │   └── submod.py               # submodule of api_a package
│   │   └── api_b                       # api_b package
│   │       ├── __init__.py             # empty init file to make the api_b folder a package
│   │       ├── mainmod.py              # main module of api_b package
│   │       └── submod.py               # submodule of api_b package
│   ├── core                            # this is where the configs live
│   │   ├── auth.py                     # authentication with OAuth2
│   │   ├── config.py                   # sample config file
│   │   └── __init__.py                 # empty init file to make the config folder a package
│   ├── __init__.py                     # empty init file to make the app folder a package
│   ├── main.py                         # main file where the fastAPI() class is called
│   ├── routes                          # this is where all the routes live
│   │   └── views.py                    # file containing the endpoints of api_a and api_b
│   └── tests                           # test package
│       ├── __init__.py                 # empty init file to make the tests folder a package
│       └── test_api.py                 # test files
├── docker-compose.yml                  # docker-compose file
├── Dockerfile                          # dockerfile
├── LICENSE                             # MIT license
├── makefile                            # Makefile to apply Python linters
├── mypy.ini                            # type checking configs
├── pyproject.toml                      # pep-518 compliant config file
├── README.md                           # a basic readme template
├── requrements-dev.in                  # .in file to enlist the top-level dev requirements
├── requirements-dev.txt                # pinned dev dependencies
├── requirements.in                     # .in file to enlist the top-level app dependencies
└── requirements.txt                    # pinned app dependencies

In the above structure, api_a and api_b are the main packages where the code of the APIs live and they are exposed by the endpoints defined in the routes folder. Here, api_a and api_b have identical logic. Basically these are dummy APIs that take an integer as input and return two random integers between zero and the input value. The purpose of including two identical APIs in the template is to demonstrate how you can decouple the logics of multiple APIs and then assemble their endpoints in the routes directory. The following snippets show the logic behind the dummy APIs.

This is a dummy submodule that houses a function called random_gen which basically generates a dict of random integers.

# This a dummy module
# This gets called in the module_main.py file
from __future__ import annotations
import random


def rand_gen(num: int) -> dict[str, int]:
    num = int(num)
    d = {
        "seed": num,
        "random_first": random.randint(0, num),
        "random_second": random.randint(0, num),
    }
    return d

The main_func in the primary module calls the rand_gen function from the submodule.

from __future__ import annotations
from app.api_a.submod import rand_gen


def main_func(num: int) -> dict[str, int]:
    d = rand_gen(num)
    return d

The endpoint is exposed like this:

# app/routes/views.py
from __future__ import annotations
#... codes regarding authentication ...

# endpoint for api_a (api_b looks identical)
@router.get("/api_a/{num}", tags=["api_a"])
async def view_a(num: int, auth: Depends =Depends(get_current_user)) -> dict[str, int]:
    return main_func_a(num)

So hitting the API with a random integer will give you a response like the following:

{
  "seed": 22,
  "random_first": 27,
  "random_second": 20
}

Further Modifications

• You can put your own API logics in the shape of api_a and api_b packages. You'll have to add additional directories like api_a and api_b if you need more APIs.

• Then expose the APIs in the routes/views.py file. You may choose to create multiple views files to organize your endpoints.

• This template uses OAuth2 based authentication and it's easy to change that. FastAPI docs has a comprehensive list of the available authentication options and instructions on how to use them.

• During deployment, you may need to change the host name and port number. To do so, just change the values of HOST and PORT variables under the environment section in the docker-compose.yml file.

• Here, containerization has been done using FastAPI author's python3.8-slim based uvicorn-gunicorn-fastapi-docker image. You may want to use a different base image that caters your usage. A few viable options are listed here.

• Although this template uses sensible Uvicorn-Gunicorn defaults, it exposes a few configs under the environment section in the docker-compose.yml file. Should you choose to tinker with them, you can do it there. Also, you can use a custom Gunicorn config file and point the location of the custom_gunicorn_conf.py file in the GUNICORN_CONF variable.

Stack

• FastAPI
• Httpx
• Uvicorn
• Gunicorn
• Pydantic
• Starlette
• Docker
• Pytest
• Pip-tools

Resources

• Docker image: uvicorn-gunicorn-fastapi-docker
• Flask divisional folder structure
• Deploying APIs built with FastAPI

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