Create Configuration class

lib/ddtrace.rb

@@ -3,6 +3,7 @@
 require 'ddtrace/tracer'
 require 'ddtrace/error'
 require 'ddtrace/pipeline'
+require 'ddtrace/configuration'
 
 # \Datadog global namespace that includes all tracing functionality for Tracer and Span classes.
 module Datadog
@@ -30,6 +31,18 @@ def self.tracer
   def self.registry
     @registry
   end
+
+  class << self
+    attr_writer :configuration
+
+    def configuration
+      @configuration ||= Configuration.new
+    end
+
+    def configure
+      yield(configuration)
+    end
+  end
 end
 
 require 'ddtrace/monkey'

lib/ddtrace/configuration.rb

@@ -0,0 +1,34 @@
+require_relative 'configuration/proxy'
+
+module Datadog
+  # Configuration provides a unique access point for configurations
+  class Configuration
+    InvalidIntegrationError = Class.new(StandardError)
+
+    def initialize(options = {})
+      @registry = options.fetch(:registry, Datadog.registry)
+    end
+
+    def [](integration_name)
+      integration = fetch_integration(integration_name)
+      Proxy.new(integration)
+    end
+
+    def use(integration_name, options = {})
+      integration = fetch_integration(integration_name)
+
+      options.each_with_object(Proxy.new(integration)) do |(name, value), proxy|
+        proxy[name] = value
+      end
+
+      integration.patch if integration.respond_to?(:patch)
+    end
+
+    private
+
+    def fetch_integration(name)
+      @registry[name] ||
+        raise(InvalidIntegrationError, "'#{name}' is not a valid integration.")
+    end
+  end
+end

lib/ddtrace/configuration/proxy.rb

@@ -0,0 +1,28 @@
+module Datadog
+  class Configuration
+    # Proxy provides a hash-like interface for fetching/setting configurations
+    class Proxy
+      def initialize(integration)
+        @integration = integration
+      end
+
+      def [](param)
+        @integration.get_option(param)
+      end
+
+      def []=(param, value)
+        @integration.set_option(param, value)
+      end
+
+      def to_h
+        @integration.to_h
+      end
+
+      alias_method :to_hash, :to_h
+
+      def reset!
+        @integration.reset_options!
+      end
+    end
+  end
+end

test/configuration_test.rb

@@ -0,0 +1,64 @@
+require 'ddtrace/configuration'
+require 'ddtrace/configurable'
+
+module Datadog
+  class ConfigurationTest < Minitest::Test
+    def setup
+      @registry = Registry.new
+      @configuration = Configuration.new(registry: @registry)
+    end
+
+    def test_use_method
+      contrib = Minitest::Mock.new
+      contrib.expect(:patch, true)
+
+      @registry.add(:example, contrib)
+      @configuration.use(:example)
+
+      assert_mock(contrib)
+    end
+
+    def test_module_configuration
+      integration = Module.new do
+        include Contrib::Base
+        option :option1
+        option :option2
+      end
+
+      @registry.add(:example, integration)
+
+      @configuration.use(:example, option1: :foo!, option2: :bar!)
+
+      assert_equal(:foo!, @configuration[:example][:option1])
+      assert_equal(:bar!, @configuration[:example][:option2])
+    end
+
+    def test_setting_a_configuration_param
+      integration = Module.new do
+        include Contrib::Base
+        option :option1
+      end
+
+      @registry.add(:example, integration)
+      @configuration[:example][:option1] = :foo
+      assert_equal(:foo, @configuration[:example][:option1])
+    end
+
+    def test_invalid_integration
+      assert_raises(Configuration::InvalidIntegrationError) do
+        @configuration[:foobar]
+      end
+    end
+
+    def test_hash_coercion
+      integration = Module.new do
+        include Contrib::Base
+        option :option1, default: :foo
+        option :option2, default: :bar
+      end
+
+      @registry.add(:example, integration)
+      assert_equal({ option1: :foo, option2: :bar }, @configuration[:example].to_h)
+    end
+  end
+end