render-cron-jobs

Render Cron Jobs

This skill covers Cron Job services on Render: how schedules run, what the platform guarantees, and how they differ from workers and workflows. Pair it with Blueprint and deploy skills when authoring render.yaml or Dashboard settings.

When to Use

• Scheduled work that starts on a cron, runs a command, and exits when finished
• Choosing between cron, background worker, or workflow for periodic or long-running jobs
• Blueprint fields for type: cron, schedule, and commands
• Constraints: no disk, single concurrent run, 12-hour max duration, private-network outbound only
• UTC scheduling pitfalls (expressions are not local time)

Expression cheat sheets, framework startCommand examples, and Heroku Scheduler migration mapping live under references/.

Configuration

• Schedule: a cron expression evaluated in UTC, not the team’s local timezone. All times in the Dashboard and Blueprints are UTC.
• Command: any valid Linux shell command or bash script path. The process must exit when work is done—billing is based on run duration (prorated by the second).
• Source:
  • Git repository — Render builds on push (same deploy model as other repo-backed services); the built artifact runs on each scheduled invocation.
  • Prebuilt Docker image — the image is pulled before each run and is not retained between runs (no warm cache of the image layer set across invocations in the same way as a long-lived service).

Constraints

• No persistent disk — cron job services cannot provision or attach Render persistent disks; plan for object storage or databases instead.
• Single-run guarantee — at most one active run per cron service at a time. A new scheduled tick does not start a second overlapping instance.
• Maximum run length: 12 hours per invocation.
• Pricing: $1/month minimum per cron job service; usage is prorated by the second beyond plan/minimum rules that apply to your account.
• Private network: cron jobs can send traffic to other services on the private network; they cannot receive inbound private-network connections (no internal hostname for accepting traffic from other services).