Signaling failures

You can actively signal a failure to by slightly changing the ping URL: append either /fail or /{exit-status} to your normal ping URL. The exit status should be a 0-255 integer. will interpret exit status 0 as success and all non-zero values as failures.


# Reports failure by appending the /fail suffix:
curl --retry 3

# Reports failure by appending a non-zero exit status:
curl --retry 3

By actively signaling failures to, you can minimize the delay from your monitored service encountering a problem to you getting notified about it.

Shell Scripts

The below shell script appends $? (a special variable that contains the exit status of the last executed command) to the ping URL:


/usr/bin/certbot renew
curl --retry 3$?


Below is a skeleton code example in Python which signals a failure when the work function returns an unexpected value or throws an exception:

import requests
URL = ""

def do_work():
    # Do your number crunching, backup dumping, newsletter sending work here.
    # Return a truthy value on success.
    # Return a falsy value or throw an exception on failure.
    return True

success = False
    success = do_work()
    # On success, requests
    # On failure, requests
    requests.get(URL if success else URL + "/fail")