Record the Delayed Job enqueue as a producer span

In collector mode the `enqueue.delayed_job` event now opens a producer
span, matching the other job backends and OpenTelemetry's own Delayed
Job instrumentation. Delayed Job has no envelope to carry trace context
across the enqueue/perform boundary, so -- like OpenTelemetry -- nothing
is injected and the producer and consumer spans are not linked.

Dual-modes the Delayed Job specs so the collector-mode span shapes are
covered alongside the agent-mode ones.

Author: unflxw

lib/appsignal/integrations/delayed_job_plugin.rb

@@ -32,7 +32,11 @@ def self.enqueue_with_instrumentation(job, block)
           return block.call(job)
         end
 
-        Appsignal.instrument("enqueue.delayed_job", "enqueue #{job.name} job") do
+        Appsignal.instrument(
+          "enqueue.delayed_job",
+          "enqueue #{job.name} job",
+          :opentelemetry_kind => :producer
+        ) do
           block.call(job)
         end
       end

spec/lib/appsignal/integrations/delayed_job_plugin_spec.rb

@@ -35,7 +35,7 @@ def perform_job(job)
 
     describe "enqueueing a job" do
       context "with an active transaction" do
-        it "records an enqueue event titled after the job" do
+        it "records an enqueue event titled after the job", :agent_mode do
           start_agent
           transaction = http_request_transaction
           set_current_transaction(transaction)
@@ -46,15 +46,40 @@ def perform_job(job)
           expect(event).to_not be_nil
           expect(event["title"]).to eq("enqueue DelayedTestJob job")
         end
+
+        it "records the enqueue as a producer span", :collector_mode do
+          start_collector_agent
+          transaction = http_request_transaction
+          set_current_transaction(transaction)
+
+          Delayed::Job.enqueue(DelayedTestJob.new)
+          Appsignal::Transaction.complete_current!
+
+          # Delayed Job has no envelope to carry trace context, so -- like
+          # OpenTelemetry's own instrumentation -- nothing is injected; the
+          # producer span is not linked to the later perform.
+          producer = event_spans.find { |s| s.name == "enqueue DelayedTestJob job" }
+          expect(producer.attributes["appsignal.category"]).to eq("enqueue.delayed_job")
+          expect(producer.kind).to eq(:producer)
+          expect(producer.parent_span_id).to eq(root_span.span_id)
+        end
       end
 
       context "without an active transaction" do
-        it "is a transparent pass-through" do
+        it "is a transparent pass-through", :agent_mode do
           start_agent
 
           expect { Delayed::Job.enqueue(DelayedTestJob.new) }
             .to change { Delayed::Backend::Test::Job.count }.by(1)
         end
+
+        it "emits no enqueue span", :collector_mode do
+          start_collector_agent
+
+          Delayed::Job.enqueue(DelayedTestJob.new)
+
+          expect(span_exporter.finished_spans.map(&:name)).to_not include("enqueue.delayed_job")
+        end
       end
 
       if DependencyHelper.active_job_present?
@@ -72,7 +97,7 @@ def perform(*)
             end)
           end
 
-          it "does not record a second enqueue event" do
+          it "does not record a second enqueue event", :agent_mode do
             start_agent
             transaction = http_request_transaction
             set_current_transaction(transaction)
@@ -89,7 +114,7 @@ def perform(*)
 
     describe "performing a job" do
       context "with a normal job" do
-        it "wraps it in a background_job transaction" do
+        it "wraps it in a background_job transaction", :agent_mode do
           start_agent
           job = Delayed::Job.enqueue(DelayedTestJob.new)
 
@@ -102,6 +127,19 @@ def perform(*)
           expect(transaction).to include_event(:name => "perform_job.delayed_job")
           expect(transaction).to include_tags("attempts" => 0, "priority" => 0)
         end
+
+        it "wraps it in a consumer span", :collector_mode do
+          start_collector_agent
+          job = Delayed::Job.enqueue(DelayedTestJob.new)
+
+          perform_job(job)
+          Appsignal::Transaction.complete_current!
+
+          expect(root_span.kind).to eq(:consumer)
+          expect(root_span.attributes["appsignal.action_name"]).to eq("DelayedTestJob#perform")
+          expect(root_span.attributes["appsignal.namespace"]).to eq("background")
+          expect(event_spans.map(&:name)).to include("perform_job.delayed_job")
+        end
       end
 
       context "with a job that raises" do
@@ -113,7 +151,7 @@ def perform
           end)
         end
 
-        it "records the error on the transaction" do
+        it "records the error on the transaction", :agent_mode do
           start_agent
           job = Delayed::Job.enqueue(DelayedErrorJob.new)
 
@@ -126,6 +164,19 @@ def perform
           expect(transaction).to have_action("DelayedErrorJob#perform")
           expect(transaction).to have_error("ExampleException", "uh oh")
         end
+
+        it "records the error on the consumer span", :collector_mode do
+          start_collector_agent
+          job = Delayed::Job.enqueue(DelayedErrorJob.new)
+
+          expect { perform_job(job) }.to raise_error(ExampleException, "uh oh")
+          Appsignal::Transaction.complete_current!
+
+          expect(root_span.kind).to eq(:consumer)
+          event = root_span.events.find { |e| e.name == "exception" }
+          expect(event.attributes["exception.type"]).to eq("ExampleException")
+          expect(event.attributes["exception.message"]).to eq("uh oh")
+        end
       end
 
       context "with a custom appsignal_name" do
@@ -140,7 +191,7 @@ def appsignal_name
           end)
         end
 
-        it "uses the custom name as the action" do
+        it "uses the custom name as the action", :agent_mode do
           start_agent
           job = Delayed::Job.enqueue(DelayedNamedJob.new)
 
@@ -163,7 +214,7 @@ def perform(*)
             end)
           end
 
-          it "uses the Active Job class as the action" do
+          it "uses the Active Job class as the action", :agent_mode do
             start_agent
 
             keep_transactions do