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External provider sources

You can distribute your own components to other dry-system users via external provider sources, which can be used as the basis for providers within any dry-system container.

Provider sources look and work the same as regular providers, which means allowing you to use their full lifecycle for creating, configuring, and registering your components.

To distribute a group of provider sources (defined in their own files), register them with Dry::System:

# my_gem
#  |- lib/my_gem/provider_sources.rb

Dry::System.register_provider_sources(:common, boot_path: File.join(__dir__, "provider_sources"))

Then, define your provider source:

# my_gem
#  |- lib/my_gem/provider_sources/exception_notifier.rb

Dry::System.register_provider_source(:exception_notifier, group: :my_gem) do
  init do
    require "some_exception_notifier"
  end

  start do
    register(:exception_notifier, SomeExceptionNotifier.new)
  end
end

Then you can use this provider source when you register a provider in a dry-system container:

# system/app/container.rb

require "dry/system/container"
require "my_gem/provider_sources"

module App
  class Container < Dry::System::Container
    register_provider(:exception_notifier, from: :my_gem)
  end
end

App::Container[:exception_notifier]

Customizing provider sources

You can customize a provider source for your application via before and after callbacks for its lifecycle steps.

For example, you can register additional components based on the provider source's own registrations via an after(:start) callback:

module App
  class Container < Dry::System::Container
    register_provider(:exception_notifier, from: :my_gem) do
      after(:start)
        register(:my_notifier, container[:exception_notifier])
      end
    end
  end
end

The following callbacks are supported:

  • before(:prepare)
  • after(:prepare)
  • before(:start)
  • after(:start)

Providing component configuration

Provider sources can define their own settings using dry-configurable’s setting API. These will be configured when the provider source is used by a provider. The other lifecycle steps in the provider souce can access the configured settings as config.

For example, here’s an extended :exception_notifier provider source with settings:

# my_gem
#  |- lib/my_gem/provider_sources/exception_notifier.rb

Dry::System.register_component(:exception_notifier, provider: :common) do
  setting :environments, default: :production, constructor: Types::Strict::Array.of(Types::Strict::Symbol)
  setting :logger

  init do
    require "some_exception_notifier"
  end

  start do
    # Now we have access to `config`
    register(:exception_notifier, SomeExceptionNotifier.new(config.to_h))
  end
end

This defines two settings:

  • :environments, which is a list of environment identifiers with default value set to [:production]
  • :logger, an object that should be used as the logger, which must be configured

To configure this provider source, you can use a configure block when defining your provider using the source:

module App
  class Container < Dry::System::Container
    register_provider(:exception_notifier, from: :my_gem) do
      require "logger"

      configure do |config|
        config.logger = Logger.new($stdout)
      end
    end
  end
end

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