Implement global configuration using configuration API

Rakefile

@@ -47,7 +47,7 @@ namespace :spec do
 
   RSpec::Core::RakeTask.new(:contrib) do |t|
     # rubocop:disable Metrics/LineLength
-    t.pattern = 'spec/**/contrib/{analytics,configurable,integration,patchable,patcher,registerable,sampling,configuration/*}_spec.rb'
+    t.pattern = 'spec/**/contrib/{analytics,configurable,integration,patchable,patcher,registerable,registry,configuration/*}_spec.rb'
   end
 
   [

lib/ddtrace.rb

@@ -1,6 +1,5 @@
 require 'thread'
 
-require 'ddtrace/registry'
 require 'ddtrace/pin'
 require 'ddtrace/tracer'
 require 'ddtrace/error'
@@ -14,39 +13,13 @@
 # \Datadog global namespace that includes all tracing functionality for Tracer and Span classes.
 module Datadog
   extend Augmentation
+  extend Configuration
 
-  @tracer = Tracer.new
-  @registry = Registry.new
-  @configuration = Configuration.new(registry: @registry)
-
-  # Default tracer that can be used as soon as +ddtrace+ is required:
-  #
-  #   require 'ddtrace'
-  #
-  #   span = Datadog.tracer.trace('web.request')
-  #   span.finish()
-  #
-  # If you want to override the default tracer, the recommended way
-  # is to "pin" your own tracer onto your traced component:
-  #
-  #   tracer = Datadog::Tracer.new
-  #   pin = Datadog::Pin.get_from(mypatchcomponent)
-  #   pin.tracer = tracer
-  class << self
-    attr_reader :tracer, :registry
-    attr_accessor :configuration
-
-    def configure(target = configuration, opts = {})
-      if target.is_a?(Configuration)
-        yield(target)
-      else
-        Configuration::PinSetup.new(target, opts).call
-      end
-    end
-  end
+  # Load and extend Contrib by default
+  require 'ddtrace/contrib/extensions'
+  extend Contrib::Extensions
 end
 
-require 'ddtrace/contrib/base'
 require 'ddtrace/contrib/active_model_serializers/integration'
 require 'ddtrace/contrib/active_record/integration'
 require 'ddtrace/contrib/aws/integration'

lib/ddtrace/configuration.rb

@@ -1,72 +1,26 @@
-require_relative 'configuration/proxy'
-require_relative 'configuration/resolver'
-require_relative 'configuration/pin_setup'
+require 'ddtrace/configuration/pin_setup'
+require 'ddtrace/configuration/settings'
 
 module Datadog
   # Configuration provides a unique access point for configurations
-  class Configuration
-    ENV_TRACE_ANALYTICS_ENABLED = 'DD_TRACE_ANALYTICS_ENABLED'.freeze
-    InvalidIntegrationError = Class.new(StandardError)
+  module Configuration
+    attr_writer :configuration
 
-    attr_writer :analytics_enabled
-
-    def initialize(options = {})
-      @registry = options.fetch(:registry) { Datadog.registry }
-      @wrapped_registry = {}
-      @analytics_enabled = nil
-    end
-
-    def analytics_enabled
-      @analytics_enabled || begin
-        if ENV.key?(ENV_TRACE_ANALYTICS_ENABLED)
-          value = ENV[ENV_TRACE_ANALYTICS_ENABLED]
-          value.to_s.downcase == 'true'
-        end
-      end
+    def configuration
+      @configuration ||= Settings.new
     end
 
-    def [](integration_name, configuration_name = :default)
-      integration = fetch_integration(integration_name)
-
-      if integration.class <= Datadog::Contrib::Integration
-        integration.configuration(configuration_name)
+    def configure(target = configuration, opts = {})
+      if target.is_a?(Settings)
+        yield(target)
       else
-        @wrapped_registry[integration_name] ||= Proxy.new(integration)
+        PinSetup.new(target, opts).call
       end
     end
 
-    def use(integration_name, options = {}, &block)
-      integration = fetch_integration(integration_name)
-
-      if integration.class <= Datadog::Contrib::Integration
-        configuration_name = options[:describes] || :default
-        filtered_options = options.reject { |k, _v| k == :describes }
-        integration.configure(configuration_name, filtered_options, &block)
-      else
-        settings = Proxy.new(integration)
-        integration.sorted_options.each do |name|
-          settings[name] = options.fetch(name, settings[name])
-        end
-      end
-
-      integration.patch if integration.respond_to?(:patch)
-    end
-
-    def tracer(options = {})
-      instance = options.fetch(:instance, Datadog.tracer)
-
-      instance.configure(options)
-      instance.class.log = options[:log] if options[:log]
-      instance.set_tags(options[:tags]) if options[:tags]
-      instance.set_tags(env: options[:env]) if options[:env]
-      instance.class.debug_logging = options.fetch(:debug, false)
-    end
-
-    private
-
-    def fetch_integration(name)
-      @registry[name] ||
-        raise(InvalidIntegrationError, "'#{name}' is not a valid integration.")
+    # Helper methods
+    def tracer
+      configuration.tracer
     end
   end
 end

lib/ddtrace/configuration/resolver.rb → lib/ddtrace/configuration/dependency_resolver.rb

@@ -1,9 +1,9 @@
 require 'tsort'
 
 module Datadog
-  class Configuration
+  module Configuration
     # Resolver performs a topological sort over the dependency graph
-    class Resolver
+    class DependencyResolver
       include TSort
 
       def initialize(dependency_graph = {})

lib/ddtrace/configuration/option.rb

@@ -0,0 +1,32 @@
+module Datadog
+  module Configuration
+    # Represents an instance of an integration configuration option
+    class Option
+      attr_reader \
+        :definition
+
+      def initialize(definition, context)
+        @definition = definition
+        @context = context
+        @value = nil
+        @is_set = false
+      end
+
+      def set(value)
+        @value = @context.instance_exec(value, &definition.setter).tap do
+          @is_set = true
+        end
+      end
+
+      def get
+        return definition.default_value unless @is_set
+        @value
+      end
+
+      def reset
+        @is_set = false
+        @value = nil
+      end
+    end
+  end
+end

lib/ddtrace/configuration/option_definition.rb

@@ -0,0 +1,27 @@
+module Datadog
+  module Configuration
+    # Represents a definition for an integration configuration option
+    class OptionDefinition
+      IDENTITY = ->(x) { x }
+
+      attr_reader \
+        :default,
+        :depends_on,
+        :lazy,
+        :name,
+        :setter
+
+      def initialize(name, meta = {}, &block)
+        @default = meta[:default]
+        @depends_on = meta[:depends_on] || []
+        @lazy = meta[:lazy] || false
+        @name = name.to_sym
+        @setter = meta[:setter] || block || IDENTITY
+      end
+
+      def default_value
+        lazy ? @default.call : @default
+      end
+    end
+  end
+end

lib/ddtrace/configuration/option_definition_set.rb

@@ -0,0 +1,18 @@
+require 'ddtrace/configuration/dependency_resolver'
+
+module Datadog
+  module Configuration
+    # Represents a set of configuration option definitions for an integration
+    class OptionDefinitionSet < Hash
+      def dependency_order
+        DependencyResolver.new(dependency_graph).call
+      end
+
+      def dependency_graph
+        each_with_object({}) do |(name, option), graph|
+          graph[name] = option.depends_on
+        end
+      end
+    end
+  end
+end

lib/ddtrace/configuration/option_set.rb

@@ -0,0 +1,6 @@
+module Datadog
+  module Configuration
+    class OptionSet < Hash
+    end
+  end
+end