dry-system-component.rb

# Component way of adding redis
# vendor/dry/system/components.rb
Dry::System.register_provider(
  :persistence,
  boot_path: Pathname(__dir__).join('components').realpath()
)

# vendor/dry/system/components/redis.rb
Dry::System.register_component(:redis, provider: :persistence) do
  init do
    require 'redis'
  end

  start do
    use :logger

    register(:redis, Redis.new(url: ENV['REDIS_URL'], logger: application[:logger]))
  end
end

# system/container.rb
require 'dry/system/container'
require_relative '../vendor/dry/system/components'

class Container < Dry::System::Container
  boot(:redis, from: :persistence)
end

dry-system-plugin.rb

# Plugin way of adding redis
# vendor/dry/system/plugins/redis.rb
module Dry
  module System
    module Plugins
      module Redis

        def self.extended(system)
          system.after(:configure, &:register_redis)
          super
        end

        def register_redis
          if registered?(:redis)
            self
          else
            register(:redis, Redis.new(url: ENV['REDIS_URL'], logger: config.logger))
          end
        end
      end
    end
  end
end

# system/container.rb
require 'dry/system/container'
require_relative '../vendor/dry/system/plugins/redis'

class Container < Dry::System::Container
  use :redis
end

dry-system-usage.rb

# Basic explicit way to add redis
# system/boot/redis.rb
Container.boot(:redis) do |application|
  init do
    require 'redis'
  end

  start do
    use :logger

    register(:redis, Redis.new(url: ENV['REDIS_URL'], logger: application[:logger]))
  end
end