MITMProxy script that fakes HTTP endpoint error

mitm-error.py

#!/usr/bin/env python3
# Install mitmdump & mitmproxy with `brew install mitmproxy`
# run with: mitmdump -s mitm-error.py
# fire requests: curl --proxy localhost:8080 https://test.example.com/test
# set up your system proxy or configure your browser to use the proxy localhost:8080
import sys
import re
import json
from mitmproxy import http, proxy, options

# Add regexes that match URLs
# if any of these match, use the response (it can be customized below)
regexes = [
    '/test$'
]

def url_matches(url, regexes):
    return any(re.search(regex, url) for regex in regexes)

# When a request is encountered, do this thing:
def request(flow):
    if url_matches(flow.request.pretty_url, regexes):
        print("Matched request: ", flow.request.pretty_url)
        flow.response = http.HTTPResponse.make(
            500, # Status code: HTTP 500 (Internal Server Error)
            json.dumps({ # Response body as bytestring
                'statusCode': 500,
                'message': 'broken'
            }).encode("utf-8"),
            { # Response headers
                'Content-Type': 'application/json'
            }
        )