pyckish 0.2.0

Pyckish is an extract/parse/validate solution to allow ease of use when dealing with AWS Lambdas.

Pyckish

AWS Lambda extractor/parser/validator"

Pyckish is an "extract, parse and validate" solution to allow ease of use when dealing with AWS Lambdas. It aims to make using Lambdas to handle HTTP requests an alternative that works similarly to other frameworks for back-end applications, like FastAPI.

Currently, it can be used to extract HTTP data that comes in the event/context dictionary. It extracts from the dictionary, parses it and validates it. It relies heavily on Pydantic, and will make your life simpler if you only like to deal with validated and correctly typed data.

Instead of doing this:

def lambda_handler(event: dict, context: dict) -> float:
    auth = event['headers']['authorization_token']
    store = event['pathParameters']['store']
    item = event['body']
    
    user = get_user(auth)
    price = get_price(item, store, user)
    return price

Do this:

import pyckish
from pyckish.http_elements import Body, Header, PathParameter
from my_models import Item


@pyckish.Lambda()
def lambda_handler(
        auth: str = Header(alias='authorization_token'),
        store: str = PathParameter(),
        item: Item = Body()
) -> float:
    user = get_user(auth)
    price = get_price(item, store, user)
    return price

And get validation and parsing free of trouble thanks to integration with Pydantic. Enjoy the advantages of a much more robust codebase, leaving behind having to extract and manage issues related to missing/wrong values.

Motivation

(Today, together with AWS API Gateway, it is possible to use only AWS Lambdas as back-end for your application. The problem is, unlike modern Frameworks, like FastAPI and Starlite, using only AWS Lambdas requires you to develop your own solutions for extracting, parsing, validating as well as creating error handling for the inputs of your code. There are solutions that allow you to use ASGI Frameworks with AWS Lambdas, like Mangum. But it is yet another technology that sits above your bulky framework. Personally, I think that the problem could be solved in a more simple and direct manner. Pyckish aims to be that solution.

Using tools like Serverless Framework with its integration with CloudFormation, many AWS Lambdas can be deployed from a single repository. Those "monorepos" solutions could also make heavy use of Pyckish in order to handle its inputs.

Right now, Pyckish is a tiny baby, and I'm not sure of its future. Weather it will become a full Framework with more capabilities than Chalice Framework, or it is going to remain as a simple "extractor/parser/validator" I do not know.

But I encourage you to try, simplicity and types will seduce you into it.)

Usage

comming soon...

Lambda Decorator

...

Custom LambdaInputElement

...

Adding Error Handlers

...