GitHub scheduled action not triggering reliably

[JackPGreen]

🏷️ Discussion Type

Bug

💬 Feature/Topic Area

Schedule & Cron Jobs

Discussion Details

Hi, I have an action that's to be triggered every hour:

on:
  workflow_dispatch:
  schedule:
    - cron: '0 * * * *'

But looking at the job history, it's running much more sporadically than that - perhaps a couple of times a day at most:

I've noticed the same behaviour in other personal projects, e.g. in another repo it should trigger every 30 minutes:

on:
  schedule:
    - cron: '*/30 * * * *'

And yet it's not:

I've tested this in an organisation-owned repo and it works fine - this issue seems to affect personal repositories only?

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[jamalkamaladdin]

Docs warn that schedule events get delayed under load, worst at minute 0, and some get dropped. Move your cron off :00:

on:
  schedule:
    - cron: '17 * * * *'

For strict hourly syncs, call gh workflow run fork-syncer.yml from an external cron instead.

Docs: https://docs.github.com/en/actions/reference/workflows-and-actions/events-that-trigger-workflows#schedule

[tp322d]

Adding to the off-minute advice: if the sync matters, make the silence visible. Add a last step to the job that curls a heartbeat URL, and alert when it hasn't been hit within about 90 minutes. Then a skipped or dropped schedule event pages you instead of being found days later. Any heartbeat or dead man's switch service does this. LastPing (https://lastping.dev/monitor/github-actions-scheduled/, free for individuals) is one, and I work on it. Its guide uses a workflow_run webhook instead of a curl step. This only detects the gap and doesn't fix the cause. As a backstop, a workflow_dispatch from an external cron needs a token that can write to Actions, and the workflow must have workflow_dispatch: enabled.