README.md

BJob - Batch jobs

BJob allows you to write batch jobs. Each job defines a set of items to operate on plus a processing method that takes one item as an argument.

BJob was designed with observability in mind, so it integrates with Batch by default.

Jobs are Ruby classes and can be invoked from anywhere in code. However, since it's so common to run them straight from the command line, a CLI is built in.

Motivation

In my experience, you have two types of Rake tasks:

1. Batch jobs, which you run either manually or from a crontab.
2. Build tasks, like preparing static assets before deploy.

For build tasks, I find plain old Make to be a much better alternative. It's designed with that goal in mind, it's language agnostic and it's much easier and straightforward to shell out. (I was shelling out all the time in my Rake tasks anyway.)

For batch jobs, Rake just doesn't work. As soon as the logic of your tasks begins to grow, so does the length of the task—there is no clear way of factoring out code in order to keep things sane. You can define global methods, but that's suboptimal, to say the least. Many times you'll create a class or module which handles that growing logic. And the Rake task will be there just to call the class.

I wrote BJob in order to clean up all those ad-hoc classes I'd been creating to handle batch jobs.

Getting started

Say you run an application which has paid user accounts. So you want to run a batch job every day, check for expired accounts and take the appropriate action:

class AccountChecker < BJob::Job
  def items(filter = nil)
    User.all
  end

  def process(user)
    if user.subscription_ended?
      user.update(plan: "free")
    end
  end
end

You can run the job over all user accounts by calling:

AccountChecker.run

You can also run the job using the built-in CLI interface:

$ bjob -r./lib/account_checker AccountChecker

In real life it's probable that you have an entry point to your application, a file which loads everything. In order to save you from repeating yourself on every call to bjob(1), you can create a .bjobrc in the project root:

$ cat .bjobrc
-r
./init

Each line is appended to Ruby's ARGV before processing arguments. So now you can call the executable like:

$ bjob AccountChecker

Installation

$ gem install bjob

License

See UNLICENSE. With love, from Educabilia.