PACKAGE.md

A simple framework to quickly compose and use multiple functionalities as endpoints.
LogicLayer is built upon FastAPI to provide a simple way to group functionalities into reusable modules.

Getting started

LogicLayer allows to group multiple endpoints with related functionality into a single module, which can be installed in a single step, and with the option to share external objects and make them available to the routes.

The unit of functionality is a Module, which must be a subclass of the LogicLayerModule class. Then you can mark its methods as module routes using the route decorator:

# echo.py
import logiclayer as ll
import platform

class EchoModule(ll.LogicLayerModule):
    def get_python_version():
        return platform.python_version()

    @ll.route("GET", "/")
    def route_status(self):
        return {
            "module": "echo", 
            "version": "0.1.0", 
            "python": self.get_python_version(),
        }

    [...more methods]

You can setup multiple methods in your module class, and only the decorated ones will be setup as routes in your module. The ll.route method accepts the same parameters as FastAPI's app.get/head/post/put methods, with the difference you can set multiple methods at once passing a list instead of the HTTP method as string:

ll.route("GET", "/")
# is the same as
ll.route(["GET"], "/")
# so this also works
ll.route(["GET", "HEAD"], "/")
# (...just be careful to leave the answer empty when needed)

Then just create a new LogicLayer instance and add the module using the add_module() method. The first argument is the prefix to the paths of all URLs for this module, and the second is the instance of the LogicLayerModule subclass:

# example.py

import requests
import logiclayer as ll
from .echo import EchoModule

layer = LogicLayer()

# this will work as a healthcheck for the app
def is_online() -> bool:
    """Checks if the machine is online."""
    res = requests.get("http://clients3.google.com/generate_204")
    return (res.status_code == 204) and (res.headers.get("Content-Length") == "0")
# healthchecks are set to run in the root `/_health` path
layer.add_check(is_online)

echo = EchoModule()
layer.add_module("/demo", echo)

The layer object is an ASGI-compatible application, that can be used with uvicorn/gunicorn to run a server, the same way as you would with a FastAPI instance.

$ pip install uvicorn[standard]
$ uvicorn example:layer

Note the example:layer parameter is the reference to the layer variable in the example module/file, which points to the ASGI app instance.

Optionally, you can also install a module in a common FastAPI instance, using the internal APIRouter instance:

app = FastAPI()
echo = EchoModule()

app.include_router(echo.router, prefix="/demo")

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© 2022 Datawheel, LLC.
This project is licensed under MIT.