Send HTTP request from one Google Cloud Function to another HTTP-triggered Google Cloud Function

main.py

# the HTTP-triggered GCF does not need to have "Allow Unauthenticated" set

import urllib
import json

import google.auth.transport.requests
import google.oauth2.id_token

url = <YOUR URL>

payload = {
    "<KEY>": "<VALUE>"
    }

data = json.dumps(payload)
data = str(data)
data = data.encode('utf-8')

req = urllib.request.Request(url, data)

auth_req = google.auth.transport.requests.Request()
id_token = google.oauth2.id_token.fetch_id_token(auth_req, url)

req.add_header("Authorization", f"Bearer {id_token}")
req.add_header('Content-Type', 'application/json')

response = urllib.request.urlopen(req)

print(response.code)

print(response.read())