Monitor Python scripts: a try/except and one HTTP request

The snippets

Create a monitor in the console (its schedule = how often the script should run, plus a grace window), copy the ping URL, and wrap your entry point.

import requests

PING = "https://ping.lastping.dev/<your-monitor-id>"

def main() -> None:
    ...  # your job

if __name__ == "__main__":
    try:
        main()
    except Exception as exc:
        requests.post(f"{PING}/fail", data=str(exc)[:10000], timeout=10)
        raise
    else:
        requests.get(PING, timeout=10)

from urllib.request import Request, urlopen

PING = "https://ping.lastping.dev/<your-monitor-id>"

def main() -> None:
    ...  # your job

if __name__ == "__main__":
    try:
        main()
    except Exception as exc:
        urlopen(Request(f"{PING}/fail", data=str(exc)[:10000].encode()), timeout=10)
        raise
    else:
        urlopen(PING, timeout=10)

import time

import requests

PING = "https://ping.lastping.dev/<your-monitor-id>"

def main() -> None:
    ...  # your job

if __name__ == "__main__":
    rid = str(int(time.time()))
    requests.get(f"{PING}/start", params={"rid": rid}, timeout=10)
    try:
        main()
    except Exception as exc:
        requests.post(f"{PING}/fail", data=str(exc)[:10000], timeout=10)
        raise
    else:
        requests.get(PING, params={"rid": rid}, timeout=10)

What this catches

The except reports what it can; the silence reports the rest.

• ✓An exception: the /fail ping opens an incident immediately, with the exception text stored on the ping.
• ✓A crash your code never sees: OOM kill, segfault in a C extension, kill -9. No success ping arrives; the grace window raises the alert.
• ✓The script never ran: missing cron entry, broken virtualenv path, dead host. Absence → incident.
• ✓A hung run: with the /start ping armed, a job stuck on a lock or a dead socket opens an incident inside the grace window.
• ✓Recovery: the next successful run closes the incident and sends a recovery notice automatically.

Questions people ask

Front-loaded answers: the most important fact first.

• How do I monitor a Python cron job?

  Wrap the entry point in try/except: on success, requests.get the monitor URL https://ping.lastping.dev/<your-monitor-id>; on exception, requests.post the error text to the /fail endpoint and re-raise so the exit code stays non-zero. If the script fails, hangs, or never starts, LastPing alerts you by email, Slack, Discord, Telegram, ntfy, Pushover, Microsoft Teams, Google Chat or webhook.

• Do I need a special library or SDK?

  No. A ping is one plain HTTP request: GET, HEAD, or POST. requests is convenient; the standard library's urllib.request works with zero dependencies.

• What if my script crashes before it can ping?

  That's the point of dead-man's-switch monitoring: a script that segfaults, is OOM-killed, or never starts sends no ping, and the missing ping itself opens the incident after the grace window. The failure path needs no working code.

• Can I see the exception in the alert trail?

  Yes. POST the exception text as the body of the /fail ping. Up to 10,000 bytes are stored with the ping event and retrievable via the API.

• Does this work outside plain scripts?

  Anywhere Python runs and can make an HTTP request: a Django management command, a task in a worker, an ETL step, a notebook job. The ping doesn't care what invoked the code.

• Is Python job monitoring free?

  Yes. LastPing is free for individuals with no monitor cap. See how it compares to Healthchecks.io and Cronitor.