purus

purus parses parameters provided from Lambda@Edge on CloudFront, and it manipulates request and response. It is named after The Purus River, or a tributary of The Amazon River.

Install

$ pip install purus

Usage

CloudFront:Lambda@Edge

purus can parse parameters of

• viewer-request
• origin-request
• origin-response
• viewer-response

# Lambda@Edge
from purus.amazon_cloudfront import CloudFrontLambdaEdge

# on viewer-request or origin-request
def lambda_handler(event: dict, _):
    # load data
    lambda_edge = CloudFrontLambdaEdge.from_event(event=event)
    
    # return on error
    if some_error_occurred:
        pseudo_payload = lambda_edge.add_pseudo_response(
            status="400",
            status_description="error_occurred"
        )
        return pseudo_payload.response.format()
    
    # redirect
    if redirect_condition:
        pseudo_payload = lambda_edge.add_pseudo_redirect_response(
            status="307",
            status_description="Redirect",
            location_url="https://redirect.example.com"
        )
        return pseudo_payload.response.format()
    
    # add headers to request
    modified_request = lambda_edge.append_request_header(
        key="X-Original-Header",
        value="Your data"
    ).append_request_header(
        key="X-Original-Header",
        value="Your additional data"
    )
    
    # to request
    return  modified_request.request.format()