How to create a Sidekiq service application without Rails

Sometimes you want to create a small Sidekiq service to process requests, without all the extra bloat (and memory usage) from a Rails framework. It turns out that creating such service is not all that hard to do. Create your application using the folders and files below as your starting point.

Gemfile

# Gemfile
source 'https://rubygems.org'
ruby "2.5.0"
git_source(:github) do |repo_name|
  repo_name = "#{repo_name}/#{repo_name}" unless repo_name.include?("/")
  "https://github.com/#{repo_name}.git"
end

gem "sidekiq"

config/sidekiq.yml

---
:concurrency: <%= ENV["CONCURRENCY"] || 25 %>
:queues:
 - default

config/application.rb

# config/application.rb

ENV["BUNDLE_GEMFILE"] ||= File.expand_path("../../Gemfile", __FILE__)

require "bundler/setup" if File.exist?(ENV["BUNDLE_GEMFILE"])
Bundler.require

ENV["RACK_ENV"] ||= "development"

module Example
 class Application
   def self.root
     @root ||= File.dirname(File.expand_path('..', __FILE__))
   end

   def self.env
     @env ||= ENV["RAILS_ENV"] || ENV["RACK_ENV"] || ENV["ENV"] || "development"
   end

   def self.logger
     @logger ||= Logger.new(STDOUT)
   end
 end
end

require_relative "initializers/sidekiq"

config/initializers/sidekiq.rb

# config/initializers/sidekiq.rb

Sidekiq.configure_server do |config|
  config.redis = { url: ENV["REDIS_URL"] }
end

app/workers/my_worker.rb

# app/workers/my_worker.rb

class MyWorker
  include Sidekiq::Worker

  def perform(*args)
    # Do work here
  end
end

Once you have created those files, then you can run the following on the command line:

bundle exec sidekiq -e ${RACK_ENV:-development} -r ./config/application.rb -C ./config/sidekiq.yml

If you want to enqueue jobs from another application using Sidekiq, its as easy as:

Sidekiq::Client.enqueue_to "default", MyWorker, "param_1" => "1", "param_2" => "2"

When you have all this working, then you can start adding things like your database connections and other gems and code to the worker. Let me know if this helps anyone or if you run into any problems!