Simple Scheduler
A scheduling add-on for Sidekiq and Heroku Scheduler that enables jobs to run at any interval without a clock process.
What is Simple Scheduler?
Simple Scheduler is a Ruby gem that extends Heroku Scheduler and Sidekiq to schedule recurring background jobs at custom intervals. It solves the limitation of Heroku Scheduler, which only supports 10-minute, hourly, or daily intervals, by allowing jobs to run at any frequency while maintaining reliability during server downtime.
Rails developers using Heroku and Sidekiq who need flexible, reliable scheduling for recurring tasks like nightly reports, weekly payroll, or frequent data syncs.
It provides a simple, configuration-driven approach to job scheduling without requiring a separate clock process, ensuring jobs run even during outages by queuing them ahead, making it production-ready and maintenance-friendly.
Overview
An enhancement for Heroku Scheduler + Sidekiq for scheduling jobs at specific times.
Use Cases
Best For
- Scheduling Sidekiq jobs at intervals not supported by Heroku Scheduler (e.g., every 2 minutes)
- Ensuring recurring tasks run reliably despite Heroku dyno restarts or downtime
- Managing nightly or weekly batch jobs like report generation or data cleanup
- Handling payroll or billing jobs on specific days of the month
- Running maintenance tasks at custom times across different time zones
- Configuring job schedules via YAML without writing custom scheduler code
Not Ideal For
- Projects not using Heroku, as it's optimized for Heroku Scheduler and requires manual setup elsewhere
- Applications needing sub-minute precision or real-time job triggering, since execution depends on Heroku Scheduler's 10-minute intervals
- Systems requiring advanced scheduling features like job dependencies or complex cron expressions beyond simple intervals
- Teams using job queues other than Sidekiq or ActiveJob, due to tight integration requirements
Pros & Cons
Pros
Allows custom intervals like minutes, hours, or weeks via a simple YAML configuration, directly addressing Heroku Scheduler's limitation to only 10-minute, hourly, or daily runs.
Queues jobs into the future with a configurable queue_ahead setting (default 6 hours), ensuring execution even during server outages, as highlighted in its production readiness.
Optional expires_after setting prevents stale jobs from running after delays, with built-in hooks for handling expired tasks via exception notifications.
Changes to the YAML file are picked up on the next scheduler run without process restarts, simplifying maintenance and updates.
Cons
Heavily dependent on Heroku Scheduler for triggering jobs; using it outside Heroku requires manual scheduling of the rake task, adding complexity.
The :at parameter has constraints—e.g., jobs with intervals less than a day only run in specified hours—and lacks direct support for multiple weekdays or monthly dates, requiring guard clauses in job code.
Changes like renaming classes or altering run times may require running a separate rake task to reset the job queue, which can be disruptive in production environments.
Does not support chaining or dependencies between scheduled jobs, forcing developers to implement custom logic within job classes for complex workflows.
Frequently Asked Questions
Related Projects
WheneverCron jobs in Ruby
Rufus-Schedulerscheduler for Ruby (at, in, cron and every jobs)
minicron🕰️ Monitor your cron jobs
sidekiq-cronScheduler / Cron for Sidekiq jobs
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