dnsresolver.py

import dns.resolver
import os
from urllib import request
import json
import time

WEBHOOK_URL = 'https://hooks.slack.com/services/' \
              '{keyhere}'


DNS_CHECK_URL = '{url.to.check}'
ENV = os.getenv('ENV', None)


def report_to_slack(exception):
    message = {
        'channel': '#slack-channel',
        'text': 'Could not resolve dns for {} on env {}. Issue: {}'
                .format(DNS_CHECK_URL, ENV, str(exception)),
        'username': '{username}',
    }
    with request.urlopen(WEBHOOK_URL, json.dumps(message).encode()) as response:
        html = response.read()


resolver = dns.resolver.Resolver()

while True:
    try:
        result = resolver.query(DNS_CHECK_URL)
        if len(result) > 1:
            report_to_slack(Exception('No A name can be resolved'))
    except Exception as ex:
        report_to_slack(ex)
    time.sleep(20)