[#1444] Pass parent trace to sidekiq job

Author: sivag-csod

lib/elastic_apm/spies/sidekiq.rb

@@ -30,7 +30,15 @@ class SidekiqSpy
       class Middleware
         def call(_worker, job, queue)
           name = SidekiqSpy.name_for(job)
-          transaction = ElasticAPM.start_transaction(name, 'Sidekiq')
+
+          transaction = if job['trace_id']
+            ElasticAPM.start_transaction(name, 'Sidekiq', trace_context: ElasticAPM::TraceContext.new(
+              traceparent: ElasticAPM::TraceContext::Traceparent.new(trace_id: job['trace_id'])
+            ))
+          else
+            ElasticAPM.start_transaction(name, 'Sidekiq')
+          end
+
           ElasticAPM.set_label(:queue, queue)
 
           yield
@@ -47,6 +55,14 @@ def call(_worker, job, queue)
         end
       end
 
+      class ParentTraceMiddleware
+        def call(job_class_or_string, job, queue, redis_pool)
+          job.merge!(
+            'trace_id' => ElasticAPM.current_transaction&.trace_id
+          )
+        end
+      end
+
       def self.name_for(job)
         klass = job['class']
 
@@ -64,6 +80,12 @@ def install_middleware
             chain.add Middleware
           end
         end
+
+        Sidekiq.configure_client do |config|
+          config.client_middleware do |chain|
+             chain.add ParentTraceMiddleware
+          end
+        end
       end
 
       # @api private