Hey everyone,
I have been trying to set up an asana webhook using lambda with an API gateway.
here is lambda’s code I’m using-
import hashlib
import hmac
import json
import logging
logger = logging.getLogger()
logger.setLevel(logging.INFO)
hook_secret = None
def lambda_handler(request, context):
global hook_secret
logging.info(“Headers: \n” + str(request[“headers”]))
logging.info(“Body: \n” + str(request[‘body’]))
if “X-Hook-Secret” in list(request[‘headers’].keys()):
if hook_secret is not None:
logging.warning(
“Second handshake request received. This could be an attacker trying to set up a new secret. Ignoring.”)
else:
# Respond to the handshake request 
logging.info(“New webhook”) # Save the secret for later to verify incoming webhooks
hook_secret = request[“headers”][“X-Hook-Secret”]
header = {‘X-Hook-Secret’: hook_secret}
response = {
‘statusCode’:‘200’,
‘headers’:header,
‘body’:{}
}
return response
elif “X-Hook-Signature” in list(request[‘headers’].keys()):
# Compare the signature sent by Asana’s API with one calculated locally.
# These should match since we now share the same secret as what Asana has stored.
signature = hmac.new(hook_secret.encode(‘ascii’, ‘ignore’),
msg=str(request.data), digestmod=hashlib.sha256).hexdigest()
if not hmac.compare_digest(signature,
request.headers[“X-Hook-Signature”].encode(‘ascii’, ‘ignore’)):
logging.warning(“Calculated digest does not match digest from API. This event is not trusted.”)
return
contents = json.loads(request.data)
logging.info(“Received payload of %s events”, len(contents[“events”]))
return “”
else:
raise KeyError
And this is the response body and header I get while testing my API gateway-
Response Body
{
"method": "POST",
"body" : "",
"statusCode":'200'
}
Response Headers
{"X-Hook-Secret":"xxxxxxxxxxxx","Access-Control-Allow-Origin":"*","X-Amzn-Trace-Id":"Root=1-xxxxxxxxxxxxxxxxxx;Sampled=0","Content-Type":"application/json"}
Every time I try to create a webhook I get an error with the message “The remote server did not respond with the handshake secret.”
I am not sure what I am doing wrong.
Please help me out, guys.