feat: faraday add support for internal spans (#873)

instrumentation/faraday/lib/opentelemetry/instrumentation/faraday/instrumentation.rb

@@ -20,6 +20,7 @@ class Instrumentation < OpenTelemetry::Instrumentation::Base
           defined?(::Faraday)
         end
 
+        option :span_kind, default: :client, validate: %i[client internal]
         option :peer_service, default: nil, validate: :string
 
         private

instrumentation/faraday/lib/opentelemetry/instrumentation/faraday/middlewares/tracer_middleware.rb

@@ -25,11 +25,13 @@ class TracerMiddleware < ::Faraday::Middleware
 
           def call(env)
             http_method = HTTP_METHODS_SYMBOL_TO_STRING[env.method]
+            config = Faraday::Instrumentation.instance.config
+
             attributes = span_creation_attributes(
-              http_method: http_method, url: env.url
+              http_method: http_method, url: env.url, config: config
             )
             tracer.in_span(
-              "HTTP #{http_method}", attributes: attributes, kind: :client
+              "HTTP #{http_method}", attributes: attributes, kind: config.fetch(:span_kind)
             ) do |span|
               OpenTelemetry.propagation.inject(env.request_headers)
 
@@ -39,21 +41,23 @@ def call(env)
 
           private
 
-          attr_reader :app
-
-          def span_creation_attributes(http_method:, url:)
+          def span_creation_attributes(http_method:, url:, config:)
             instrumentation_attrs = {
               'http.method' => http_method,
-              'http.url' => OpenTelemetry::Common::Utilities.cleanse_url(url.to_s)
+              'http.url' => OpenTelemetry::Common::Utilities.cleanse_url(url.to_s),
+              'faraday.adapter.name' => app.class.name
             }
             instrumentation_attrs['net.peer.name'] = url.host if url.host
-            config = Faraday::Instrumentation.instance.config
             instrumentation_attrs['peer.service'] = config[:peer_service] if config[:peer_service]
+
             instrumentation_attrs.merge!(
               OpenTelemetry::Common::HTTP::ClientContext.attributes
             )
           end
 
+          # Versions prior to 1.0 do not define an accessor for app
+          attr_reader :app if Gem::Version.new(Faraday::VERSION) < Gem::Version.new('1.0.0')
+
           def tracer
             Faraday::Instrumentation.instance.tracer
           end

instrumentation/faraday/test/opentelemetry/instrumentation/faraday/middlewares/tracer_middleware_test.rb

@@ -110,6 +110,33 @@
         _(span.attributes['peer.service']).must_equal 'example:faraday'
       end
 
+      it 'defaults to span kind client' do
+        instrumentation.instance_variable_set(:@installed, false)
+        instrumentation.install
+
+        client.get('/success')
+
+        _(span.kind).must_equal :client
+      end
+
+      it 'allows overriding the span kind to internal' do
+        instrumentation.instance_variable_set(:@installed, false)
+        instrumentation.install(span_kind: :internal)
+
+        client.get('/success')
+
+        _(span.kind).must_equal :internal
+      end
+
+      it 'reports the name of the configured adapter' do
+        instrumentation.instance_variable_set(:@installed, false)
+        instrumentation.install
+
+        client.get('/success')
+
+        _(span.attributes.fetch('faraday.adapter.name')).must_equal Faraday::Adapter::Test.name
+      end
+
       it 'prioritizes context attributes over config for peer service name' do
         instrumentation.instance_variable_set(:@installed, false)
         instrumentation.install(peer_service: 'example:faraday')