Kushojin

Kushojin gathers changes to the attributes of the ActiveRecord model and sends them externally via Fluentd. This is useful for logging, tracking and real-time aggregation of accesses involving database updates. Since Fluentd is used for external transmission, Kushojin can respond flexibly to various requests.

Add this line to your application's Gemfile:

gem 'kushojin'

And then execute:

$ bundle

Or install it yourself as:

$ gem install kushojin

Kushojin::Config.logger = Fluent::Logger::FluentLogger.new(nil, host: "localhost", port: 24224)

class User < ApplicationRecord
  record_changes
end

class UsersController < ApplicationController
  send_changes

  def create
    User.create(params[:user])
  end
end

$ curl -X POST -d "user[name]=bill&user[age]=20" http://localhost:3000/users
# output: users.create {"event":"create","request_id":"4afd0731-dd25-4668-b769-2017dbdd3642","table_name":"users","id":1,"changes":{"name":[null,"bill"],"age":[null,20]}}

Changes is recorded when the model is created, updated and destroyed. The :only option can be used same as filters of controller.

class User < ApplicationRecord
  record_changes only: [:create, :destroy]
end

$ curl -X POST -d "user[name]=bill&user[age]=20" http://localhost:3000/users
# output: users.create {"event":"create","request_id":"4afd0731-dd25-4668-b769-2017dbdd3642","table_name":"users","id":1,"changes":{"name":[null,"bill"],"age":[null,20]}}

$ curl -X PATCH -d "user[age]=21" http://localhost:3000/users/1
# no output

Kushojin sends model changes with some information:

• tag: Controller name and action name concatenated with a period.
• event: The event which model is changed on.
• table_name: Table name of the model.
• primary key: Primary key name and value.
• changes: Model changes without its primary key, created_at, and updated_at. It contains pairs of attribute name and before/after values.
• request_id: Request ID.

It is able to pass a customized sender to add additional information.

class CustomSender < Kushojin::Sender::EachSender
  private

  # Add "user_id"
  def serialize(change, controller)
    super.merge!("user_id" => controller.current_user.id)
  end
end

class MessagesController < ApplicationController
  send_changes Kushojin::ControllerMethods::SendChangeCallback.new(sender: CustomSender.new)

  def current_user
    return_user_record_with_any_authentication_logic
  end

  def create
    Message.create(params[:message])
  end
end

You can pass in a class or an instance to change behaviors of the callbacks.

class CustomCallbacks
  # Must be able to respond to after_create, after_update, and after_destroy.
  def after_create(record); end
  def after_update(record); end
  def after_destroy(record); end
end

class User < ApplicationRecord
  record_changes CustomCallbacks.new
end

You can override options of Recording changes in subclass.

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
  record_changes
end

class User < ApplicationRecord
  record_changes only: [:create, :destroy]
end

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/nowlinuxing/kushojin.

The gem is available as open source under the terms of the MIT License.