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Transactional-Outbox for Rails.

• Publishing event data in transactional-outbox pattern
• Polling multiple databases and outbox tables
• Can use your own publisher/subscriber
• Custom Metrics with dogstatsd
• Ensure message ordering

Supported publisher

• Google Cloud Pub/Sub

• Ruby 2.6+
• Rails 6.0+

Add this line to your application's Gemfile:

gem 'trabox'

And then execute:

bundle install
bin/rails g trabox:configure

This will generate config file config/initializers/trabox.rb.

Optional:

bundle binstubs trabox

# generate model
bin/rails g trabox:model <NAME>

# Help
bin/rails g trabox:model --help
Usage:
  rails generate trabox:model NAME [field[:type][:index] field[:type][:index]] [options]
...

additional option: --polymorphic=<NAME> This option is inserted references column in generated outbox model. This use to associate event record with outbox record when the application is designed immutable data model.

example:bin/rails g trabox:model event --polymorphic=event

class CreateEvents < ActiveRecord::Migration[6.1]
  def change
    create_table :events do |t|
      t.references :event, polymorphic: true, null: false # additional column
      t.binary :event_data
      t.string :message_id
      t.datetime :published_at

      t.timestamps
    end
  end
end

Insert events to publish into the generated outbox table as part of the local transaction.

# Your rails application
ActiveRecord::Base.transaction do
  user = User.create! name: 'hoge'

  Event.create! event_data: <serialized_user_event>
end

bin/trabox relay

# Help
bin/trabox relay -h
Usage: trabox relay [OPTIONS]

Overwrite configuration

    -l, --limit NUM
    -i, --interval SEC
    -L, --[no-]lock
        --log-level LEVEL

bin/trabox subscribe

# Help
bin/trabox subscribe -h
Usage: trabox subscribe [OPTIONS]

Overwrite configuration

        --log-level LEVEL

The default namespace of metrics is trabox.
The namespace can be changed with TRABOX_METRIC_NAMESPACE environment variable.

Bug reports and pull requests are welcome.

bundle install

docker-compose up

setup db

cd spec/rails_app
bin/rails db:setup

create topic / subscribe

rake trabox:pubsub_setup

bin/rspec

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