render-cron-jobs

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Translated

Configures and troubleshoots scheduled tasks on Render using cron job services. Use when the user needs to run something on a schedule, write a cron expression, set up a periodic job, migrate from Heroku Scheduler, choose between cron jobs and background workers, or fix a cron that isn't firing. Trigger terms: cron job, scheduled task, periodic job, cron expression, schedule, run every, timer, Heroku Scheduler migration.

17installs

Sourcerender-oss/skills

Added on2026-08-26

NPX Install

npx skill4agent add render-oss/skills render-cron-jobs

SKILL.md Content

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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 because longer runs consume more billable compute. Confirm current details at Render pricing.
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: Running cron jobs incurs an additional cost. Confirm current details at Render pricing.
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).

Execution Behavior

Manual “Trigger Run” while a run is active: Render cancels the active run, then starts a new one.
New Git build / deploy does not affect a run already in progress—the in-flight process keeps using the revision it started with until it exits.
Docker-based crons: the image is pulled fresh for each run; do not assume layer or image reuse across invocations like a continuously running container.
UTC everywhere: cron expressions and “midnight” in docs mean UTC. A common mistake is copying a local-time schedule into the expression without converting to UTC.

Cron vs Worker vs Workflow

Need	Use	Why
Periodic task under 12h	Cron Job	Scheduled, simple, exits when done
Continuous job processing	Background Worker	Always running, polls a queue
Periodic but over 12h	Background Worker	No 12h cron run ceiling
Scheduled parallel compute	Cron Job + Workflow	Cron triggers workflow runs on a schedule; workflows fan out or orchestrate parallel steps

Blueprint Configuration

Cron services use type: cron
with a schedule
and the usual build/start and env wiring:

yaml

services:
  - type: cron
    name: nightly-cleanup
    schedule: "0 * * * *" # hourly at minute 0 — must be quoted in YAML
    buildCommand: pip install -r requirements.txt
    startCommand: python cleanup.py
    envVars:
      - key: DATABASE_URL
        fromDatabase:
          name: my-db
          property: connectionString

schedule
: standard five-field cron (

minute hour day-of-month month day-of-week

), UTC.

buildCommand
/ startCommand
: same roles as other non-Docker services; Docker images use image + start command as configured for image-backed crons.
envVars
: same patterns as web services and workers (secrets, linked databases, etc.).

YAML note: the

schedule

value must be quoted so characters like

are not parsed as YAML aliases or flow syntax.

Common Patterns

Database cleanup — archive or delete stale rows on a schedule
Report generation — build CSV/PDF and upload to object storage or email
External API sync — pull or push batches on an interval
Cache warming — hit endpoints or rebuild caches before peak traffic
Scheduled emails — digest or reminder sends driven by cron + mail/API

References

Topic	File
Expression examples, framework commands, errors, env vars	`references/cron-patterns.md`
Heroku Scheduler → Render mapping, blueprint example	`references/migration-from-scheduler.md`

Related Skills

render-deploy — First-time deploy, service creation, Dashboard flow
render-blueprints — Full
```
render.yaml
```
schema, previews, common mistakes
render-background-workers — Long-lived processes, queues, no 12h cap
render-workflows — Orchestrated and parallel jobs, often triggered on a schedule from cron