Servus

A disciplined service-object pattern for Ruby and Rails.

Most mature Rails apps grow a services/ directory. Servus gives each service the same shape — one entrypoint, one response object, and opt-in layers for validation, guards, events, and async.

Full documentation at zarpay.github.io/servus

Add to your Gemfile:

gem 'servus'

bundle install

Generate a service:

rails g servus:service treasury/transfer_gold from_account to_account gold_dragons

Write the service:

module Treasury
  module TransferGold
    class Service < Servus::Base
      def initialize(from_account:, to_account:, gold_dragons:)
        @from_account = from_account
        @to_account = to_account
        @gold_dragons = gold_dragons
      end

      def call
        @from_account.withdraw!(@gold_dragons)
        @to_account.deposit!(@gold_dragons)

        success(
          transferred: @gold_dragons,
          from_balance: @from_account.balance,
          to_balance: @to_account.balance
        )
      end
    end
  end
end

Call it:

result = Treasury::TransferGold::Service.call(
  from_account: crown_account,
  to_account: night_watch_account,
  gold_dragons: 50
)

result.success?          # => true
result.data.transferred  # => 50
result.data.from_balance # => 950
result.data.to_balance   # => 550

• Schema validation — JSON Schema for arguments, results, and failure data
• Error handling — HTTP-aligned error hierarchy with rescue_from
• Guards — reusable precondition checks with structured errors
• Events — decouple follow-up work from the service that triggered it
• Async execution — .call_async runs the same service through ActiveJob
• Lazy resolvers — accept an instance or an ID, resolve on first access
• Logging — automatic call, outcome, and duration logging
• Rails integration — controller helpers, generators, autoloading via Railtie

• Ruby >= 3.0
• ActiveSupport >= 8.0
• Rails integration is automatic via Railtie; core works in any Ruby application

MIT