perform_every

Cron jobs for Rails. Just add perform_every "5 minutes" to any job.

Requires Postgres and a configured Rails' ActiveJob adapter, like delayed_job or sidekiq.

Include gem 'perform_every' and then run:

bundle install
rails generate perform_every:active_record
rails db:migrate

Create a new job app/jobs/example_job.rb:

class ExampleJob < ApplicationJob
  queue_as :default

  # multiple perform_every and perform_at are allowed
  perform_every "10 minutes"
  perform_at "October 1st, 2030"
  perform_at "October 1st, 2050"

  # This job runs every 10 minutes and on October 1st, 2030 and 2050.
  # No `perform` parameters are allowed, because `perform_every` will
  # just use the configured `Rails.config.active_job.queue_adapter` to
  # queue this job.
  def perform
    User.all.each do |user|
      send_cat_meme(user) #priceless
    end
  end
end

Finally start the worker which will enqueue jobs:

rails perform_every:run

perform_every "interval", {:accuracy => 1.minute}

perform_every "day at five"
perform_every "weekday at five"
perform_every "day at 5 pm"
perform_every "tuesday at 5 pm"
perform_every "wed at 5 pm"
perform_every "day at 16:30"
perform_every "day at noon"
perform_every "day at midnight"
perform_every "tuesday"
perform_every "day at 5 pm on America/Los_Angeles"
perform_every "day at 6 pm in Asia/Tokyo"
perform_every "3 hours"
perform_every "4 months"
perform_every "5 minutes"

• interval should be >= 1.minute
• interval default timezone is UTC
• accuracy is set to 1.minute by default (see notes below)
• multiple unique perform_every can be added

perform_at "timestamp", {:accuracy => 1.minute}

perform_at "2017-12-12"
perform_at "2017-12-12 12:00:00 America/New_York"
perform_at "October 1st, 2050"

• timestamp default timezone is UTC
• accuracy is set to 1.minute by default (see notes below)
• multiple unique perform_at an be added

rails perform_every:run     # Run scheduler
rails perform_every:cleanup # Remove deprecated jobs from database
rails perform_every:reset   # Reset persisted jobs in database

• Several workers (rails perform_every:run) can be started. During a leader election phase one worker will become master. This is done via Postgres Advisory Locks and with_advisory_lock gem. An exclusive session level advisory lock is obtained. If the worker dies, another worker will become master and take over.
• Workers will only enqueue jobs to your backend queue adapter.
• Workers will gracefully shutdown when SIGINT or SIGTERM is received.
• Job state is persited in Postgres in table perform_every.
• perform_at and perform_every statements can be added and removed between deploys, the workers support rolling deploys. Obsolete jobs are marked as deprecated in table perform_every. Run rails perform_every:cleanup after deploys to delete deprecated tasks.
• Enable Rails.config.log_level = :debug to output verbose logging to understand scheduling logic.
• Accuracy is set to 1 minute by default. If a job is scheduled to run at 4:00pm, the perform_every worker has until 4:01pm to actually schedule the job.
  Accuracy is important in case things go wrong. Here is another example: Every day at 8am a job is supposed to send out email newsletters. This can only happen between 8am and 9am. perform_every "day at 8am", {:accuracy => 1.hour} ensures that if no workers are alive between 8am and 9am the newsletter job would not be scheduled after 9:01am anymore.