Check own MQTT server using AWS lambda and send alarm messages using AWS SNS in case of failure

lambda_function.py

"""
Check if own MQTT server runs
"""
import json
import paho
import boto3
import paho.mqtt.client as mqtt
import ssl
import time
import os
import datetime
import urllib

endpoint = os.environ.get('endpoint')
username = os.environ.get('username')
password = os.environ.get('password')
snsmessage = {
    'topic': os.environ.get('snsmessagetopic'),
    'body': "HEARTBEAT failed"
}
rcv = False

ssmClient = boto3.client('ssm')

def on_connect(client, userdata, flags, rc):
    client.subscribe("#")

def on_message(client, userdata, msg):
    receiveTime = datetime.datetime.utcnow()
    message = msg.payload.decode("utf-8")
    global rcv
    rcv = True

def lambda_handler(event, context):
    client = mqtt.Client()
    client.username_pw_set(username=username, password=password)
    client.on_connect = on_connect
    client.on_message = on_message
    client.connect(endpoint, 1883, 10)
    client.loop_start()
    time.sleep(15) # wait
    client.loop_stop()
    if rcv == False:
        send_to_sns(snsmessage)
        return("ALERT: alert message sent")
    else:
        return("OK: no alert message sent")

def send_to_sns(message):
    sns = boto3.client('sns')
    sns.publish(
        TopicArn=message['topic'],
        Message=message['body']
    )
    return