Dead Man’s Switch for n8n: Webhook Heartbeats to Google Sheets + Slack

Keep scheduled n8n jobs honest with a Dead Man’s Switch—webhook heartbeats to Google Sheets and Slack alerts

This n8n workflow acts as a dead man’s switch for scheduled jobs: your job sends a signed webhook heartbeat, the workflow records it in Google Sheets, and it automatically alerts in Slack if a job stops checking in within its expected run window.

What this workflow does

• Receives webhook heartbeats: It accepts a POST webhook containing a job_id and validates an x-heartbeat-secret header against a configured shared secret.
• Validates registration: It looks up the job_id in a Google Sheets “jobs” registry and returns 404 if the job is not registered.
• Updates heartbeat status: For matching jobs, it writes the last_heartbeat timestamp to the row, sets status to OK, and clears last_alert_at.
• Sends recovery alerts: If the job was previously in an alerting state, it posts a recovery message to your configured Slack channel.
• Detects missed runs every 15 minutes: It periodically loads all active jobs from Google Sheets and calculates overdue jobs using expected_every_minutes plus a grace period.
• Prevents alert spam: It suppresses repeat alerts using a configurable re-alert window.
• Alerts on overdue (missed/never-seen): For each overdue job, it posts a missed-run (or never-seen) alert to Slack and writes back last_alert_at and status to avoid immediate re-alerting.
• Confirms receipt: The heartbeat endpoint responds with 200 JSON including job_id and the recorded timestamp.

Use cases

• SaaS operators monitoring critical background workflows (billing, sync jobs, imports) and catching silent failures early.
• Automation engineers ensuring scheduled n8n processes keep reporting health to a central registry.
• Teams using Slack for on-call-style notifications when a job misses its expected run window.

Technical details

• Google Sheets integration via a “jobs” sheet (columns include job_id, job_name, expected_every_minutes, grace_minutes, last_heartbeat, status, last_alert_at, active, alert_...).
• Slack node for missed-run alerts and recovery notifications.
• Workflow logic uses nodes including if, set, code, no op, slack, and filter.