instrumentation.rb in opentelemetry-instrumentation-rack-0.23.0

- old
+ new
@@ -10,57 +10,74 @@
   module Instrumentation
     module Rack
       # The Instrumentation class contains logic to detect and install the Rack
       # instrumentation
       class Instrumentation < OpenTelemetry::Instrumentation::Base
-        install do |config|
+        install do |_config|
           require_dependencies
-
-          retain_middleware_names if config[:retain_middleware_names]
         end
 
         present do
           defined?(::Rack)
         end
 
         option :allowed_request_headers,  default: [],    validate: :array
         option :allowed_response_headers, default: [],    validate: :array
         option :application,              default: nil,   validate: :callable
         option :record_frontend_span,     default: false, validate: :boolean
-        option :retain_middleware_names,  default: false, validate: :boolean
         option :untraced_endpoints,       default: [],    validate: :array
         option :url_quantization,         default: nil,   validate: :callable
         option :untraced_requests,        default: nil,   validate: :callable
         option :response_propagators,     default: [],    validate: :array
+        # This option is only valid for applicaitons using Rack 2.0 or greater
+        option :use_rack_events,          default: false, validate: :boolean
 
+        # Temporary Helper for Sinatra and ActionPack middleware to use during installation
+        #
+        # @example Default usage
+        #   Rack::Builder.new do
+        #     use *OpenTelemetry::Instrumentation::Rack::Instrumenation.instance.middleware_args
+        #     run lambda { |_arg| [200, { 'Content-Type' => 'text/plain' }, body] }
+        #   end
+        # @return [Array] consisting of a middleware and arguments used in rack builders
+        def middleware_args
+          if config.fetch(:use_rack_events, false) == true && defined?(::Rack::Events)
+            [::Rack::Events, [OpenTelemetry::Instrumentation::Rack::Middlewares::EventHandler.new]]
+          else
+            [OpenTelemetry::Instrumentation::Rack::Middlewares::TracerMiddleware]
+          end
+        end
+
         private
 
         def require_dependencies
+          require_relative 'middlewares/event_handler' if defined?(Rack::Events)
           require_relative 'middlewares/tracer_middleware'
         end
 
-        MissingApplicationError = Class.new(StandardError)
-
-        # intercept all middleware-compatible calls, retain class name
-        def retain_middleware_names
-          next_middleware = config[:application]
-          raise MissingApplicationError unless next_middleware
-
-          while next_middleware
-            if next_middleware.respond_to?(:call)
-              next_middleware.singleton_class.class_eval do
-                alias_method :__call, :call
-
-                def call(env)
-                  env['RESPONSE_MIDDLEWARE'] = self.class.to_s
-                  __call(env)
-                end
-              end
+        def config_options(user_config)
+          config = super(user_config)
+          config[:allowed_rack_request_headers] = config[:allowed_request_headers].compact.each_with_object({}) do |header, memo|
+            key = header.to_s.upcase.gsub(/[-\s]/, '_')
+            case key
+            when 'CONTENT_TYPE', 'CONTENT_LENGTH'
+              memo[key] = build_attribute_name('http.request.header.', header)
+            else
+              memo["HTTP_#{key}"] = build_attribute_name('http.request.header.', header)
             end
+          end
 
-            next_middleware = next_middleware.instance_variable_defined?('@app') &&
-                              next_middleware.instance_variable_get('@app')
+          config[:allowed_rack_response_headers] = config[:allowed_response_headers].each_with_object({}) do |header, memo|
+            memo[header] = build_attribute_name('http.response.header.', header)
+            memo[header.to_s.upcase] = build_attribute_name('http.response.header.', header)
           end
+
+          config[:untraced_endpoints]&.compact!
+          config
+        end
+
+        def build_attribute_name(prefix, suffix)
+          prefix + suffix.to_s.downcase.gsub(/[-\s]/, '_')
         end
       end
     end
   end
 end