fix: clear OTel context after span execution

temporalio/lib/temporalio/contrib/open_telemetry.rb

@@ -78,6 +78,11 @@ def _attach_context(headers)
           ::OpenTelemetry::Context.attach(context) if context
         end
 
+        # @!visibility private
+        def _detach_context(context_token)
+          ::OpenTelemetry::Context.detach(context_token) if context_token
+        end
+
         # @!visibility private
         def _context_from_headers(headers)
           carrier = headers[@header_key]
@@ -206,7 +211,7 @@ def initialize(root, next_interceptor)
 
           # @!visibility private
           def execute(input)
-            @root._attach_context(input.headers)
+            token = @root._attach_context(input.headers)
             info = Activity::Context.current.info
             @root._with_started_span(
               name: "RunActivity:#{info.activity_type}",
@@ -217,6 +222,8 @@ def execute(input)
                 'temporalActivityID' => info.activity_id
               }
             ) { super }
+          ensure
+            @root._detach_context(token)
           end
         end
 
@@ -236,7 +243,7 @@ def init(outbound)
 
           # @!visibility private
           def execute(input)
-            _attach_context(Temporalio::Workflow.info.headers)
+            token = _attach_context(Temporalio::Workflow.info.headers)
             Workflow.with_completed_span("RunWorkflow:#{Temporalio::Workflow.info.workflow_type}", kind: :server) do
               super
             ensure
@@ -246,11 +253,13 @@ def execute(input)
                 exception: $ERROR_INFO # steep:ignore
               )
             end
+          ensure
+            _detach_context(token)
           end
 
           # @!visibility private
           def handle_signal(input)
-            _attach_context(Temporalio::Workflow.info.headers)
+            token = _attach_context(Temporalio::Workflow.info.headers)
             Workflow.with_completed_span(
               "HandleSignal:#{input.signal}",
               links: _links_from_headers(input.headers),
@@ -261,11 +270,13 @@ def handle_signal(input)
               Workflow.completed_span("FailHandleSignal:#{input.signal}", kind: :internal, exception: e)
               raise
             end
+          ensure
+            _detach_context(token)
           end
 
           # @!visibility private
           def handle_query(input)
-            _attach_context(Temporalio::Workflow.info.headers)
+            token = _attach_context(Temporalio::Workflow.info.headers)
             Workflow.with_completed_span(
               "HandleQuery:#{input.query}",
               links: _links_from_headers(input.headers),
@@ -282,11 +293,13 @@ def handle_query(input)
               )
               raise
             end
+          ensure
+            _detach_context(token)
           end
 
           # @!visibility private
           def validate_update(input)
-            _attach_context(Temporalio::Workflow.info.headers)
+            token = _attach_context(Temporalio::Workflow.info.headers)
             Workflow.with_completed_span(
               "ValidateUpdate:#{input.update}",
               attributes: { 'temporalUpdateID' => input.id },
@@ -305,11 +318,13 @@ def validate_update(input)
               )
               raise
             end
+          ensure
+            _detach_context(token)
           end
 
           # @!visibility private
           def handle_update(input)
-            _attach_context(Temporalio::Workflow.info.headers)
+            token = _attach_context(Temporalio::Workflow.info.headers)
             Workflow.with_completed_span(
               "HandleUpdate:#{input.update}",
               attributes: { 'temporalUpdateID' => input.id },
@@ -326,6 +341,8 @@ def handle_update(input)
               )
               raise
             end
+          ensure
+            _detach_context(token)
           end
 
           # @!visibility private
@@ -341,6 +358,14 @@ def _attach_context(headers)
             end
           end
 
+          # @!visibility private
+          def _detach_context(context_token)
+            # See _attach_context above for why we have to disable scheduler even for these simple operations
+            Temporalio::Workflow::Unsafe.durable_scheduler_disabled do
+              @root._detach_context(context_token)
+            end
+          end
+
           # @!visibility private
           def _links_from_headers(headers)
             # See _attach_context above for why we have to disable scheduler even for these simple operations

temporalio/sig/temporalio/contrib/open_telemetry.rbs

@@ -16,7 +16,8 @@ module Temporalio
         ) -> void
 
         def _apply_context_to_headers: (Hash[String, untyped] headers, ?context: untyped) -> void
-        def _attach_context: (Hash[String, untyped] headers) -> void
+        def _attach_context: (Hash[String, untyped] headers) -> Object?
+        def _detach_context: (Object? token) -> void
         def _context_from_headers: (Hash[String, untyped] headers) -> untyped
         def _with_started_span: [T] (
           name: String,
@@ -29,7 +30,8 @@ module Temporalio
         class WorkflowInbound < Worker::Interceptor::Workflow::Inbound
           def initialize: (TracingInterceptor root, Worker::Interceptor::Workflow::Inbound next_interceptor) -> void
 
-          def _attach_context: (Hash[String, untyped] headers) -> void
+          def _attach_context: (Hash[String, untyped] headers) -> Object?
+          def _detach_context: (Object? token) -> void
           def _links_from_headers: (Hash[String, untyped] headers) -> Array[untyped]
         end
 
@@ -61,4 +63,4 @@ module Temporalio
       end
     end
   end
-end
+end

temporalio/test/contrib/open_telemetry_test.rb

@@ -13,6 +13,8 @@ def initialize(tracer)
 
       def execute(scenario)
         case scenario.to_sym
+        when :success_return_trace_id
+          OpenTelemetry::Trace.current_span.context.hex_trace_id
         when :fail_first_attempt
           raise 'Intentional activity failure' if Temporalio::Activity::Context.current.info.attempt == 1
 
@@ -49,6 +51,8 @@ def execute(scenario)
           Temporalio::Contrib::OpenTelemetry::Workflow.with_completed_span('custom-can-span') do
             raise Temporalio::Workflow::ContinueAsNewError, :complete
           end
+        when :activity_success_return_trace_id
+          Temporalio::Workflow.execute_activity(TestActivity, :success_return_trace_id, start_to_close_timeout: 30)
         when :activity_fail_benign
           Temporalio::Workflow.execute_activity(TestActivity, :fail_benign, start_to_close_timeout: 30)
         else
@@ -608,6 +612,26 @@ def test_illegal_calls_on_context
       ContextCurrentPatch.do_illegal_thing = false
     end
 
+    def test_otel_context_cleared
+      traced_wf_trace_id = nil
+      traced_act = trace_workflow(:activity_success_return_trace_id) do |handle|
+        traced_wf_trace_id = handle.result
+      end
+      assert !traced_act.children.empty?
+
+      untraced_wf_trace_id = nil
+      untraced_span = trace_workflow(
+        :activity_success_return_trace_id,
+        start_with_untraced_client: true,
+        check_root: false
+      ) do |handle|
+        untraced_wf_trace_id = handle.result
+      end
+      assert_empty untraced_span.children
+
+      assert traced_wf_trace_id != untraced_wf_trace_id
+    end
+
     ExpectedSpan = Data.define( # rubocop:disable Layout/ClassStructure
       :name,
       :children,