fix: remove version tag if dd_service is not applied

lib/datadog/tracing/tracer.rb

@@ -394,7 +394,7 @@ def start_span(
             on_error: on_error,
             resource: resource,
             service: service,
-            tags: resolve_tags(tags),
+            tags: resolve_tags(tags, service),
             type: type,
             id: id,
             &block
@@ -408,7 +408,7 @@ def start_span(
             resource: resource,
             service: service,
             start_time: start_time,
-            tags: resolve_tags(tags),
+            tags: resolve_tags(tags, service),
             type: type,
             id: id
           )
@@ -420,15 +420,20 @@ def start_span(
       end
       # rubocop:enable Lint/UnderscorePrefixedVariableName
 
-      def resolve_tags(tags)
-        if @tags.any? && tags
-          # Combine default tags with provided tags,
-          # preferring provided tags.
-          @tags.merge(tags)
-        else
-          # Use provided tags or default tags if none.
-          tags || @tags.dup
+      def resolve_tags(tags, service)
+        merged_tags = if @tags.any? && tags
+                        # Combine default tags with provided tags,
+                        # preferring provided tags.
+                        @tags.merge(tags)
+                      else
+                        # Use provided tags or default tags if none.
+                        tags || @tags.dup
+                      end
+        # Remove version tag if service is not the default service
+        if merged_tags.key?(Core::Environment::Ext::TAG_VERSION) && service != @default_service
+          merged_tags.delete(Core::Environment::Ext::TAG_VERSION)
         end
+        merged_tags
       end
 
       # Manually activate and deactivate the trace, when the span completes.

spec/datadog/tracing/tracer_spec.rb

@@ -126,6 +126,18 @@
             expect(span.get_tag('my')).to eq('tag')
           end
 
+          context 'contains version and span.service is not equal to the default tracer service' do
+            let(:tracer_options) { { default_service: 'global-service', tags: { 'version' => '1.1.0' } } }
+            let(:service) { 'my-service' }
+            it 'does not set version on the span' do
+              expect(tracer.default_service).to eq('global-service')
+              expect(span.service).not_to eq('my-service')
+
+              expect(tracer.tags).to include('version' => '1.1.0')
+              expect(span.tags).not_to include('version')
+            end
+          end
+
           context 'and default tags are set on the tracer' do
             let(:tracer_options) { { tags: default_tags } }