Use dry-system-hanami settings prototype

system/container.rb

@@ -3,12 +3,14 @@
 require 'dry/system/container'
 require 'dry/system/hanami'
 require_relative '../lib/types'
+require_relative './settings'
 
 # General container class for project dependencies
 #
 # {http://dry-rb.org/gems/dry-system/ Dry-system documentation}
 class Container < Dry::System::Container
   extend Dry::System::Hanami::Resolver
+  setting :settings
 
   # use :bootsnap
   use :env
@@ -32,7 +34,24 @@ class Container < Dry::System::Container
   # polls
   register_folder! 'polls/operations'
 
+
   configure do |config|
     config.env = Hanami.env
+    config.settings = Settings.load(root, config.env)
+  end
+
+  def self.settings
+    config.settings
+  end
+
+  # Combines a settings hash from keys prefixed with `scope` value
+  # @param scope [#to_s]
+  # @return [Hash{Symbol=>Object}]
+  def self.settings_for(scope)
+    hash = settings.to_hash
+    prefix = /^#{Regexp.escape(scope.to_s)}_/
+    hash.keys.grep(prefix).each_with_object({}) do |key, result|
+      result[key.to_s.gsub(prefix, '').to_sym] = hash[key]
+    end
   end
 end

system/hanami_settings.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+require 'dotenv'
+
+class Dry::System::Hanami::Settings
+  SettingValueError = Class.new(StandardError)
+
+  module Types
+    include Dry::Types.module
+
+    module Required
+      String = Types::Strict::String.constrained(min_size: 1)
+    end
+
+    module Optional
+      String = Required::String.optional
+    end
+  end
+
+  def self.warn_generated(setting, value)
+    env = setting.to_s.upcase
+    ENV[env] = value
+    warn <<~ERROR
+        Please, set #{env} in `.env`:
+
+            #{env}=#{value.inspect}
+
+    ERROR
+    value
+  end
+
+  def self.schema
+    @schema ||= {}
+  end
+
+  def self.setting(name, type = nil)
+    settings(name => type)
+  end
+
+  def self.settings(new_schema)
+    check_schema_duplication(new_schema)
+    @schema = schema.merge(new_schema)
+
+    self
+  end
+
+  def self.check_schema_duplication(new_schema)
+    shared_keys = new_schema.keys & schema.keys
+
+    raise ArgumentError, "Setting :#{shared_keys.first} has already been defined" if shared_keys.any?
+  end
+  private_class_method :check_schema_duplication
+
+  def self.load(root, env)
+    build_config(schema, dotenv_data(root, env))
+  end
+
+  # @param [Settings] schema
+  # @param [Hash] defaults
+  # @return [Dry::Configurable::Config]
+  def self.build_config(schema, defaults = {})
+    Class.new do
+      extend Dry::Configurable
+
+      schema.each do |key, type|
+        env_var = key.to_s.upcase
+        value = ENV.fetch(env_var) { defaults[env_var] }
+
+        begin
+          value = type[value] if type
+        rescue StandardError => e
+          raise SettingValueError, "error typecasting +#{key}+: #{e}"
+        end
+
+        setting key, value
+      end
+    end.config
+  end
+end

system/settings.rb

@@ -0,0 +1,10 @@
+# frozen_string_literal: true
+
+require_relative 'hanami_settings'
+
+class Settings < Dry::System::Hanami::Settings
+  setting :database_url, Types::Required::String.default('postgres://test@db/test')
+
+  setting :dependency_base_url, Types::Required::String.default('url')
+  setting :dependency_something_else, Types::Required::String.default('something else')
+end