wip

lib/datadog/tracing/component.rb

@@ -54,8 +54,7 @@ def build_tracer(settings, agent_settings, logger:)
           span_sampler: build_span_sampler(settings),
           writer: writer,
           tags: build_tracer_tags(settings),
-          _inherit_parent_service: false
-          #_inherit_parent_service: settings.tracing.inherit_parent_service
+          inherit_parent_service: settings.tracing.inherit_parent_service
         )
       end
 

lib/datadog/tracing/configuration/settings.rb

@@ -144,6 +144,16 @@ def self.extended(base)
                 o.setter { |header_tags, _| Configuration::HTTP::HeaderTags.new(header_tags) }
               end
 
+              # Whether spans inherit their parent's service name, when span `service` is not explicitly set.
+              # If `true`, the spans will use the service name from its parent span.
+              # If `false`, the spans will use the global service name (`c.service`).
+              # @default `false`
+              # @return [Boolean]
+              option :inherit_parent_service do |o|
+                o.default false
+                o.type :bool
+              end
+
               # Enable 128 bit trace id generation.
               #
               # @default `DD_TRACE_128_BIT_TRACEID_GENERATION_ENABLED` environment variable, otherwise `true`

lib/datadog/tracing/span_operation.rb

@@ -49,7 +49,7 @@ def initialize(
         trace_id: nil,
         type: nil,
         links: nil,
-        _inherit_parent_service: false
+        inherit_parent_service: false
       )
         # Ensure dynamically created strings are UTF-8 encoded.
         #
@@ -91,7 +91,7 @@ def initialize(
         # Subscribe :on_error event
         @events.on_error.wrap_default(&on_error) if on_error.is_a?(Proc)
 
-        @_inherit_parent_service = _inherit_parent_service
+        @inherit_parent_service = inherit_parent_service
 
         # Start the span with start time, if given.
         start(start_time) if start_time
@@ -442,7 +442,7 @@ def message
       # mutation by reference; when this span is returned,
       # we don't want this SpanOperation to modify it further.
       def build_span
-        service = self.service || (@parent&.service if @_inherit_parent_service)
+        service = self.service || (@parent&.service if @inherit_parent_service)
 
         Span.new(
           @name,

lib/datadog/tracing/trace_operation.rb

@@ -77,15 +77,15 @@ def initialize(
         trace_state: nil,
         trace_state_unknown_fields: nil,
         remote_parent: false,
-        _inherit_parent_service: false
+        inherit_parent_service: false
       )
         # Attributes
         @id = id || Tracing::Utils::TraceId.next_id
         @max_length = max_length || DEFAULT_MAX_LENGTH
         @parent_span_id = parent_span_id
         @sampled = sampled.nil? ? true : sampled
         @remote_parent = remote_parent
-        @_inherit_parent_service = _inherit_parent_service
+        @inherit_parent_service = inherit_parent_service
 
         # Tags
         @agent_sample_rate = agent_sample_rate
@@ -254,7 +254,7 @@ def build_span(
             tags: tags,
             trace_id: trace_id,
             type: type,
-            _inherit_parent_service: @_inherit_parent_service
+            inherit_parent_service: @inherit_parent_service
           )
         rescue StandardError => e
           Datadog.logger.debug { "Failed to build new span: #{e}" }

lib/datadog/tracing/tracer.rb

@@ -59,7 +59,7 @@ def initialize(
         span_sampler: Sampling::Span::Sampler.new,
         tags: {},
         writer: Writer.new,
-        _inherit_parent_service: false
+        inherit_parent_service: false
       )
         @trace_flush = trace_flush
         @default_service = default_service
@@ -69,7 +69,7 @@ def initialize(
         @span_sampler = span_sampler
         @tags = tags
         @writer = writer
-        @_inherit_parent_service = _inherit_parent_service
+        @inherit_parent_service = inherit_parent_service
       end
 
       # Return a {Datadog::Tracing::SpanOperation span_op} and {Datadog::Tracing::TraceOperation trace_op}
@@ -330,15 +330,15 @@ def build_trace(digest = nil)
             trace_state_unknown_fields: digest.trace_state_unknown_fields,
             remote_parent: digest.span_remote,
             default_service: @default_service,
-            _inherit_parent_service: @_inherit_parent_service,
+            inherit_parent_service: @inherit_parent_service,
           )
         else
           TraceOperation.new(
             hostname: hostname,
             profiling_enabled: profiling_enabled,
             remote_parent: false,
             default_service: @default_service,
-            _inherit_parent_service: @_inherit_parent_service,
+            inherit_parent_service: @inherit_parent_service,
           )
         end
       end

spec/datadog/core/configuration/components_spec.rb

@@ -425,6 +425,7 @@
           end
         end
         let(:span_sampler) { be_a(Datadog::Tracing::Sampling::Span::Sampler) }
+        let(:inherit_parent_service) { false }
         let(:default_options) do
           {
             default_service: settings.service,
@@ -434,6 +435,7 @@
             sampler: sampler,
             span_sampler: span_sampler,
             writer: writer,
+            inherit_parent_service: inherit_parent_service,
           }
         end
 

spec/datadog/tracing/configuration/settings_spec.rb

@@ -284,6 +284,37 @@ def propagation_style_inject
       end
     end
 
+    describe '#inherit_parent_service' do
+      subject(:inherit_parent_service) { settings.tracing.inherit_parent_service }
+
+      it { is_expected.to be false }
+
+      context "when inherit_parent_service" do
+        before { settings.tracing.inherit_parent_service = value }
+
+        context 'is set to true' do
+          let(:value) { true }
+
+          it { is_expected.to be true }
+        end
+
+        context 'is set to false' do
+          let(:value) { false }
+
+          it { is_expected.to be false }
+        end
+      end
+    end
+
+    describe '#inherit_parent_service=' do
+      it 'updates the #inherit_parent_service setting' do
+        expect { settings.tracing.inherit_parent_service = true }
+          .to change { settings.tracing.inherit_parent_service }
+                .from(false)
+                .to(true)
+      end
+    end
+
     describe '#header_tags' do
       subject(:header_tags) { settings.tracing.header_tags }
 

spec/datadog/tracing/tracer_spec.rb

@@ -259,29 +259,55 @@
       end
 
       context 'when nesting spans' do
-        it 'propagates parent span and uses default service name' do
+        subject!(:nested_spans) do
           tracer.trace('parent', service: 'service-parent') do
             tracer.trace('child1') { |s| s.set_tag('tag', 'tag_1') }
             tracer.trace('child2', service: 'service-child2') { |s| s.set_tag('tag', 'tag_2') }
           end
+        end
 
-          expect(spans).to have(3).items
+        context "when inherit_parent_service is false" do
+          it 'propagates parent span and uses default service name' do
+            expect(spans).to have(3).items
 
-          child1, child2, parent = spans # Spans are sorted alphabetically by operation name
+            child1, child2, parent = spans # Spans are sorted alphabetically by operation name
 
-          expect(parent).to be_root_span
-          expect(parent.name).to eq('parent')
-          expect(parent.service).to eq('service-parent')
-
-          expect(child1.parent_id).to be(parent.id)
-          expect(child1.name).to eq('child1')
-          expect(child1.service).to eq('service-parent')
-          expect(child1.get_tag('tag')).to eq('tag_1')
-
-          expect(child2.parent_id).to be(parent.id)
-          expect(child2.name).to eq('child2')
-          expect(child2.service).to eq('service-child2')
-          expect(child2.get_tag('tag')).to eq('tag_2')
+            expect(parent).to be_root_span
+            expect(parent.name).to eq('parent')
+            expect(parent.service).to eq('service-parent')
+
+            expect(child1.parent_id).to be(parent.id)
+            expect(child1.name).to eq('child1')
+            expect(child1.service).to eq(tracer.default_service)
+            expect(child1.get_tag('tag')).to eq('tag_1')
+
+            expect(child2.parent_id).to be(parent.id)
+            expect(child2.name).to eq('child2')
+            expect(child2.service).to eq('service-child2')
+            expect(child2.get_tag('tag')).to eq('tag_2')
+          end
+        end
+
+        context "when inherit_parent_service is true" do
+          let(:tracer_options) { super().merge(inherit_parent_service: true) }
+
+          it "propagates parent span and uses parent's service name" do
+            expect(spans).to have(3).items
+
+            child1, child2, parent = spans # Spans are sorted alphabetically by operation name
+
+            expect(parent).to be_root_span
+            expect(parent.name).to eq('parent')
+            expect(parent.service).to eq('service-parent')
+
+            expect(child1.parent_id).to be(parent.id)
+            expect(child1.name).to eq('child1')
+            expect(child1.service).to eq('service-parent')
+
+            expect(child2.parent_id).to be(parent.id)
+            expect(child2.name).to eq('child2')
+            expect(child2.service).to eq('service-child2')
+          end
         end
 
         it 'trace has a runtime ID and PID tags' do