powertools-oas-validator 0.6.4

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powertools-oas-validator

Introduction

Powertools for AWS Lambda (Python) is an awesome set of tools for supercharging your lambdas. Powertools supports validating incoming requests (or event in PT lingo) against JSONSchema which is not ideal if you are using OpenAPI schemas to define your API contracts.

The Powertools OAS Validator adds a decorator that you can use with your lambda handlers and have the events validated against an OpenAPI schema instead.

Installation

Poetry: poetry add powertools-oas-validator

Pip: pip install powertools-oas-validator

Usage

Decorate your functions with @validate_request(oas_path="openapi.yaml") and your request/event (and schema) will be validated on a request.

Minimal Example

from typing import Dict
from aws_lambda_powertools.event_handler import APIGatewayRestResolver, Response
from aws_lambda_powertools.utilities.typing import LambdaContext
from powertools_oas_validator.middleware import validate_request


app = APIGatewayRestResolver()

@app.post("/example")
def example() -> Response:
  ...

@validate_request(oas_path="openapi.yaml")
def lambda_handler(event: Dict, context: LambdaContext) -> Dict:
    response = app.resolve(event, context)

    return response

Error Handling

If the validation fails, the decorator throws a SchemaValidatonError with relevant information about the failed validation.

Example of a SchemaValidatonError:

from aws_lambda_powertools.utilities.validation import SchemaValidationError

SchemaValidatonError(
  name="test-path.test-endpoint.requestBody[param_1]",
  path=["test-path", "test-endpoint", "requestBody", "param_1"],
  validation_message="'not an integer' is not of type 'integer'.",
  message="'not an integer' is not of type 'integer'",
  rule="int",
  rule_definition="type",
  value="'not an integer'"
)

Articles

• OpenAPI Spec and AWS Lambda Powertools

Know Issues

While all validation errors are caught, there is only limited information about the various errors. The decorator will try its best to throw a SchemaValidatonError (same as the Powertools validator would), with as many of the optional attributes as possible.

In summary, it is possible that not all SchemaValidationErrors's will have the correct name and path attributes.

Contributions

Please make a pull request and I will review it ASAP.