fix(rails): avoid serializing jobs for telemetry

Author: solnic

sentry-rails/lib/sentry/rails/active_job.rb

@@ -126,8 +126,7 @@ def record_producer_span(job, &enqueue)
                 {
                   system: messaging_system(job),
                   message_id: job.job_id,
-                  destination: job.queue_name,
-                  body_size: body_size { job.serialize }
+                  destination: job.queue_name
                 }.compact
               },
               default_retry_count: -> { executions(job) },

sentry-rails/spec/active_job/shared_examples/tracing/producer_span.rb

@@ -24,22 +24,6 @@
       expect(publish_span[:timestamp]).not_to be_nil
     end
 
-    it "records messaging.message.body.size as the JSON byte length of the serialized job, arguments included" do
-      short_greeting = "hi"
-      long_greeting = "héllo wörld"
-
-      within_parent_transaction do
-        greeting_job.perform_later(short_greeting)
-        greeting_job.perform_later(long_greeting)
-      end
-
-      parent = transactions.find { |t| t.contexts.dig(:trace, :op) == "test" }
-      body_sizes = parent.spans.select { |s| s[:op] == "queue.publish" }.map { |s| s[:data]["messaging.message.body.size"] }
-      expect(body_sizes).to all(be_an(Integer))
-      expect(body_sizes.last - body_sizes.first)
-        .to eq(JSON.generate(long_greeting).bytesize - JSON.generate(short_greeting).bytesize)
-    end
-
     it "records the same messaging.system on the producer span and the consumer transaction" do
       within_parent_transaction do
         successful_job.perform_later

sentry-rails/spec/active_job/test_adapter_spec.rb

@@ -9,6 +9,28 @@
   it_behaves_like "a Sentry-instrumented ActiveJob backend"
   it_behaves_like "an ActiveJob backend that supports distributed tracing"
 
+  context "when a custom serializer changes the job payload" do
+    let(:configure_sentry) { proc { |config| config.traces_sample_rate = 1.0 } }
+
+    it "enqueues the same custom payload with and without a sampled parent" do
+      custom_job = job_fixture do
+        def serialize
+          @serialization_count = (@serialization_count || 0) + 1
+          super.merge("serialization_count" => @serialization_count)
+        end
+
+        def perform; end
+      end
+
+      custom_job.perform_later
+      untraced_count = last_enqueued_payload["serialization_count"]
+      within_parent_transaction { custom_job.perform_later }
+
+      expect(untraced_count).to eq(1)
+      expect(last_enqueued_payload["serialization_count"]).to eq(untraced_count)
+    end
+  end
+
   context "when the job data cannot be encoded as JSON" do
     let(:configure_sentry) { proc { |config| config.traces_sample_rate = 1.0 } }
     let(:unencodable_argument) { "\xFF".dup.force_encoding(Encoding::UTF_8) }