FastAPI package that ease usage of AWS Cognito Auth. This package provides basic functions/tools which helps developers to use Cognito JWT.

• Python >=3.8
• FastAPI
• AWS Cognito Service

pip install fastapi-cognito

This is the simple example of how to use this package:

• Create app

from fastapi import FastAPI

app = FastAPI()

All mandatory fields are added in CognitoSettings BaseSettings object. Settings can be added in different ways. You can provide all required settings in .yaml or .json files, or your global BaseSettings file. Note that userpools field is Dict, FIRST user pool in a dict will be set as default automatically if userpool_name is not provided in CognitoAuth object. All fields shown in example below, are also required in .json or .yaml file (with syntax matching those files.)

You should also import BaseSettings from pydantic if you are going to use global BaseSettings object.

• Provide settings that are mandatory for CognitoAuth to work. You can provide one or more userpools.
  • app_client_id field for userpool besides string, can contain multiple string values provided within list, tuple or set

from pydantic_settings import BaseSettings
from pydantic.types import Any

class Settings(BaseSettings):
    check_expiration: bool = True
    jwt_header_prefix: str = "Bearer"
    jwt_header_name: str = "Authorization"
    userpools: dict[str, dict[str, Any]] = {
        "eu": {
            "region": "USERPOOL_REGION",
            "userpool_id": "USERPOOL_ID",
            "app_client_id": ["APP_CLIENT_ID_1", "APP_CLIENT_ID_2"] # Example with multiple ids
        },
        "us": {
            "region": "USERPOOL_REGION",
            "userpool_id": "USERPOOL_ID",
            "app_client_id": "APP_CLIENT_ID"
        },
        ...
    }

settings = Settings()

This example below shows how global BaseSettings object can be mapped to CognitoSettings and passed as param to CognitoAuth. If we were using .yaml or .json, we should call .from_yaml(filename) or .from_json(filename) methods on CognitoSettings object.

• Instantiate CognitoAuth and pass previously created settings as settings param.

from fastapi_cognito import CognitoAuth, CognitoSettings

# default userpool(eu) will be used if there is no userpool_name param provided.
cognito_eu = CognitoAuth(
  settings=CognitoSettings.from_global_settings(settings)
)
cognito_us = CognitoAuth(
  settings=CognitoSettings.from_global_settings(settings), userpool_name="us"
)

• This is a simple endpoint that is protected by Cognito, it uses FastAPI dependency injection to resolve all required operations and get Cognito JWT. It can be used later to add more security to endpoints and to get required data about user which token belongs to.

from fastapi_cognito import CognitoToken
from fastapi import Depends

@app.get("/")
def hello_world(auth: CognitoToken = Depends(cognito_eu.auth_required)):
    return {"message": "Hello world"}

If authentication should be optional, we can use cognito_eu.auth_optional

Example:

from fastapi_cognito import CognitoToken
from fastapi import Depends

@app.get("/")
def hello_world(auth: CognitoToken = Depends(cognito_eu.auth_optional)):
    return {"message": "Hello world"}

In case your token payload contains additional values, you can provide custom token model instead of CognitoToken. If there is no custom token model provided, CognitoToken will be set as a default model. Custom model should be provided to CognitoAuth object.

Example:

class CustomTokenModel(CognitoToken):
    custom_value: Optional[str] = None


cognito = CognitoAuth(
    settings=CognitoSettings.from_global_settings(settings),
    # Here we provide custom token model
    custom_model=CustomTokenModel
)

@app.get("/")
def hello_world(auth: CustomTokenModel = Depends(cognito.auth_required)):
    return {"message": f"Hello {auth.custom_value}"}