Self-Hosted Cron Monitor

Self-Hosted Cron Monitor

Docker Compose stack that monitors scheduled jobs via heartbeat URLs. Each cron job pings a unique URL after completing; if the ping does not arrive within the expected window, the monitor sends an email alert. A lightweight self-hosted alternative to Dead Man's Snitch or Cronitor.

What Is Included

• Monitor Service — Node.js app that tracks heartbeat URLs and their expected schedules
• Dashboard — Web UI showing all monitored jobs, last ping time, and current status
• Email Alerting — Sends an alert when a job misses its schedule; sends a recovery email when it resumes
• REST API — GET /ping/:token endpoint that cron jobs call after each successful run

How It Works

• Run docker compose up -d
• Open the dashboard and create a monitor: set the name, expected schedule, and grace period
• Append the generated ping URL to your cron job: your-command && curl -s http://monitor/ping/TOKEN
• If the URL is not called within schedule plus grace period, an email alert fires automatically

What You Get

• docker-compose.yml — Node.js app with SQLite storage and persistent volume
• Dockerfile — Node 22 Alpine image
• src/ — full application source (editable)
• .env.example — SMTP settings and alert email address
• README.md — setup guide and cron integration examples

Service URLs

Requirements

Docker Engine with the Compose plugin. SMTP credentials for outgoing alert emails (Gmail app password, SendGrid free tier, or similar).