How to add schedule auto run rake task to rails

I. Introduction

• Sometimes, we must to run some task with schedule. Rails support us to do this by gem "whenerver" and rake task.
• Rake task will make somethings you want to do and it repeat manytimes, so you must to run rake task instead of rewrite your code.
• Gem "whenever" will make schedule to run your task auto and repeat.

II. Installation

Firstly, we need to install gem "whenever":

• Add to Gemfile

gem "whenever"

• Run command bundle install

III. Simple example

In this example, we want to create some notice to do to user every 2 days to remind their work. Then, we need to create a rake task and a schedule to do rake task:

1. Create rake task

We need to generate rake task by this command:

rails g task todos auto_create
create lib/tasks/todos.rake

It will generate our new rake task in file lib/tasks/todos.rake with the contents:

namespace :todos do
  desc "TODO"
  task :auto_create => :environment do
  end
end

Then, we need to add somethings we want to do in this task:

namespace :todos do
  desc "Auto Register ToDo"
  task auto_create: :environment do
    User.visible.each do |user|
      user.to_dos.create comment: "somethings to do"
    end
  end
end

By this way, we have a rake task to create to do for all user when run this command:

rake todos:auto_create

2. Create schedule to run rake task auto

Getting started with those command:

cd /apps/my-great-project
wheneverize .

After that, it will create an initial file: config/schedule.rb

In this file, you can create schedule easily by this simple code:

every 2.days do
  rake "to_dos:auto_create"
end

That's enough for our simple example, but whenever gem can do more.

IV. More about whenever gem

• If include require: false after gem "whenever" on Gemfile, the gem will be installed, but won't be loaded into a process unless you explicitly call require "whenever".
• It has many way to create schedule in the time you want, for example:

every 1.day, at: "5:00am" do
    //something
end

every 5.minutes do
    //something
end

every :hour do
    //something
end

every :weekday do
    //something
end

every :monday, at: "8:00am" do
    //something
end

every :reboot do
    //something
end

Or you can use this format:

every "* * * * *" do
    //something
end

with meaning:

• min (0 - 59)
• hour (0 - 23)
• day of month (1 - 31)
• month (1 - 12)
• day of week (0 - 6) ~ (sunday = 0)

V. Conclusion

This is a good way to run some tasks auto and repeat with schedule in rails. I hope you find this article useful. Thanks for reading!