feat: include otel as custom sampling contex

sentry-opentelemetry/lib/sentry/opentelemetry/span_processor.rb

@@ -48,7 +48,16 @@ def on_start(otel_span, parent_context)
             parent_sampled: trace_data.parent_sampled,
             baggage: trace_data.baggage,
             start_timestamp: otel_span.start_timestamp / 1e9,
-            origin: SPAN_ORIGIN
+            origin: SPAN_ORIGIN,
+            custom_sampling_context: {
+              otel: otel_context_hash(otel_span).merge(
+                kind: otel_span.kind,
+                instrumentation_scope: {
+                  name: otel_span.instrumentation_scope.name,
+                  version: otel_span.instrumentation_scope.version
+                }
+              )
+            }
           }
 
           Sentry.start_transaction(**options)

sentry-opentelemetry/spec/sentry/opentelemetry/span_processor_spec.rb

@@ -154,6 +154,7 @@
 
     it 'starts a sentry transaction on otel root span' do
       expect(Sentry).to receive(:start_transaction).and_call_original
+
       subject.on_start(root_span, empty_context)
 
       span_id = root_span.context.hex_span_id
@@ -175,6 +176,32 @@
       expect(transaction.baggage).to eq(nil)
     end
 
+    it 'includes otel context in custom sampling context' do
+      sampling_context = nil
+      Sentry.configuration.traces_sampler = lambda do |context|
+        sampling_context = context
+        0.5
+      end
+
+      subject.on_start(root_span, empty_context)
+
+      expect(sampling_context).to include(:otel)
+      otel_context = sampling_context[:otel]
+
+      expect(otel_context).to include(
+        kind: root_span.kind,
+        instrumentation_scope: {
+          name: root_span.instrumentation_scope.name,
+          version: root_span.instrumentation_scope.version
+        }
+      )
+
+      expect(otel_context).to include(attributes: root_span.attributes)
+
+      resource_attributes = root_span.resource.attribute_enumerator.to_h
+      expect(otel_context).to include(resource: resource_attributes)
+    end
+
     context 'with started transaction' do
       let(:transaction) do
         subject.on_start(root_span, empty_context)