Basic Flask snippet to handle AWS SNS messages and subscription

snsread.py

from flask import Flask, request
import requests
import json

app = Flask(__name__)

def msg_process(msg, tstamp):
    js = json.loads(msg)
    msg = 'Region: {0} / Alarm: {1}'.format(
        js['Region'], js['AlarmName']
    )
    # do stuff here, like calling your favorite SMS gateway API

@app.route('/', methods = ['GET', 'POST', 'PUT'])
def sns():
    # AWS sends JSON with text/plain mimetype
    try:
        js = json.loads(request.data)
    except:
        pass

    hdr = request.headers.get('X-Amz-Sns-Message-Type')
    # subscribe to the SNS topic
    if hdr == 'SubscriptionConfirmation' and 'SubscribeURL' in js:
        r = requests.get(js['SubscribeURL'])

    if hdr == 'Notification':
        msg_process(js['Message'], js['Timestamp'])

    return 'OK\n'

if __name__ == '__main__':
    app.run(
        host = "0.0.0.0",
        port = 5000,
        debug = True
    )

Thank you for sharing this code. I am getting following error while parsing a Notification, subscription is successful. Please help.

x.x.x.x - - [07/Oct/2018 08:44:44] "POST /login HTTP/1.1" 500 -
Traceback (most recent call last):
  File "/home/ubuntu/.local/lib/python2.7/site-packages/flask/app.py", line 2309, in __call__
    return self.wsgi_app(environ, start_response)
  File "/home/ubuntu/.local/lib/python2.7/site-packages/flask/app.py", line 2295, in wsgi_app
    response = self.handle_exception(e)
  File "/home/ubuntu/.local/lib/python2.7/site-packages/flask/app.py", line 1741, in handle_exception
    reraise(exc_type, exc_value, tb)
  File "/home/ubuntu/.local/lib/python2.7/site-packages/flask/app.py", line 2292, in wsgi_app
    response = self.full_dispatch_request()
  File "/home/ubuntu/.local/lib/python2.7/site-packages/flask/app.py", line 1815, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/home/ubuntu/.local/lib/python2.7/site-packages/flask/app.py", line 1718, in handle_user_exception
    reraise(exc_type, exc_value, tb)
  File "/home/ubuntu/.local/lib/python2.7/site-packages/flask/app.py", line 1813, in full_dispatch_request
    rv = self.dispatch_request()
  File "/home/ubuntu/.local/lib/python2.7/site-packages/flask/app.py", line 1799, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/opt/project2app.py", line 33, in sns
    msg_process(js['Subject'], js['Message'])
  File "/opt/project2app.py", line 10, in msg_process
    js = json.loads(msg)
  File "/usr/lib/python2.7/json/__init__.py", line 339, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python2.7/json/decoder.py", line 364, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python2.7/json/decoder.py", line 382, in raw_decode
    raise ValueError("No JSON object could be decoded")
ValueError: No JSON object could be decoded

Thank you, works great.