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Celery beat periodic tasks with RunVouch

Celery beat is a single process that publishes tasks on a schedule. If it dies, or a worker for that queue is not running, tasks are late or never run, and Flower will not page you.

How it runs on Celery beat

Inside the task function with the Python client (recommended), or wrap the worker-side command if the task shells out.

Store the key

An environment variable on the worker processes; beat itself does not need the key.

Wrap the job

from celery import Celery
from celery.schedules import crontab
import runvouch

app = Celery("jobs", broker="redis://redis:6379/0")
app.conf.beat_schedule = {"nightly-report": {"task": "jobs.nightly_report", "schedule": crontab(hour=2, minute=0)}}

@app.task(bind=True, max_retries=2)
def nightly_report(self):
    with runvouch.vouch("nightly-report", evidence=lambda: {"rows": n > 0}) as run:
        n = build_report(run)

rv fails open: if RunVouch is unreachable the job still runs and you get one warning line.

Register the cadence and caps

rv agent nightly-report --cadence 24h --grace 30m --max-runtime 1h --evidence --cap-run-cost 2

Register the agent once, from anywhere with the key. Cadence is what turns a schedule that stopped into an alert; --evidence makes a run without evidence a failure; the caps pause the agent when it overspends.

What goes silent on Celery beat

• Beat down means no task is even published; MISSED is the only external signal.
• A task that is published but never consumed (wrong queue, no worker) is neither failed nor succeeded; it is a MISSED start.
• max_retries around an LLM call repeats the spend; the per-run cost cap and retry-storm detector cover it.

What RunVouch detects

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