fix: Share Faraday Attrs with Adapter Spans (#1266)

The Faraday gem has additional http attributes that are sometimes missing or difficult to derive in Adapter instrumentations.

instrumentation/faraday/Appraisals

@@ -4,14 +4,12 @@
 #
 # SPDX-License-Identifier: Apache-2.0
 
-appraise 'faraday-0.17' do
-  gem 'faraday', '~> 0.17.6'
+%w[0.17.6 1.0 2.0].each do |version|
+  appraise "faraday-#{version}" do
+    gem 'faraday', "~> #{version}"
+  end
 end
 
-appraise 'faraday-1.x' do
-  gem 'faraday', '~> 1.0'
-end
-
-appraise 'faraday-2.x' do
-  gem 'faraday', '~> 2.0'
+appraise 'faraday-latest' do
+  gem 'faraday'
 end

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

@@ -33,31 +33,34 @@ def call(env)
             attributes = span_creation_attributes(
               http_method: http_method, url: env.url, config: config
             )
-            tracer.in_span(
-              "HTTP #{http_method}", attributes: attributes, kind: config.fetch(:span_kind)
-            ) do |span|
-              OpenTelemetry.propagation.inject(env.request_headers)
 
-              app.call(env).on_complete { |resp| trace_response(span, resp.status) }
-            rescue ::Faraday::Error => e
-              trace_response(span, e.response[:status]) if e.response
+            OpenTelemetry::Common::HTTP::ClientContext.with_attributes(attributes) do |attrs, _|
+              tracer.in_span(
+                "HTTP #{http_method}", attributes: attrs, kind: config.fetch(:span_kind)
+              ) do |span|
+                OpenTelemetry.propagation.inject(env.request_headers)
 
-              raise
+                app.call(env).on_complete { |resp| trace_response(span, resp.status) }
+              rescue ::Faraday::Error => e
+                trace_response(span, e.response[:status]) if e.response
+
+                raise
+              end
             end
           end
 
           private
 
           def span_creation_attributes(http_method:, url:, config:)
-            instrumentation_attrs = {
+            attrs = {
               'http.method' => http_method,
               '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
-            instrumentation_attrs['peer.service'] = config[:peer_service] if config[:peer_service]
+            attrs['net.peer.name'] = url.host if url.host
+            attrs['peer.service'] = config[:peer_service] if config[:peer_service]
 
-            instrumentation_attrs.merge!(
+            attrs.merge!(
               OpenTelemetry::Common::HTTP::ClientContext.attributes
             )
           end

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

@@ -20,6 +20,7 @@
         stub.get('/success') { |_| [200, {}, 'OK'] }
         stub.get('/failure') { |_| [500, {}, 'OK'] }
         stub.get('/not_found') { |_| [404, {}, 'OK'] }
+        stub.get('/show-shared-attributes') { |_| [200, {}, OpenTelemetry::Common::HTTP::ClientContext.attributes.to_json] }
       end
     end
   end
@@ -31,17 +32,15 @@
     @orig_propagation = OpenTelemetry.propagation
     propagator = OpenTelemetry::Trace::Propagation::TraceContext.text_map_propagator
     OpenTelemetry.propagation = propagator
+    instrumentation.instance_variable_set(:@installed, false)
+    instrumentation.install
   end
 
   after do
     OpenTelemetry.propagation = @orig_propagation
   end
 
   describe 'first span' do
-    before do
-      instrumentation.install
-    end
-
     describe 'given a client with a base url' do
       it 'has http 200 attributes' do
         response = client.get('/success')
@@ -101,6 +100,18 @@
         )
       end
 
+      it 'ammends attributes to client context' do
+        response = client.get('/show-shared-attributes')
+        shared_attributes = JSON.parse(response.body)
+        expected_attributes = {
+          'http.method' => 'GET', 'http.url' => 'http://example.com/show-shared-attributes',
+          'faraday.adapter.name' => 'Faraday::Adapter::Test',
+          'net.peer.name' => 'example.com'
+        }
+
+        _(shared_attributes).must_equal expected_attributes
+      end
+
       it 'accepts peer service name from config' do
         instrumentation.instance_variable_set(:@installed, false)
         instrumentation.install(peer_service: 'example:faraday')