Racecar instrumentation (#1284)

* WIP racecar instrumentation

* Change to subscriber for racecar instrumentation

* Update to use transactions rather than spans

* Racecar WIP

* Updated Racecar instrumentation and specs

* Ignore racecar spec if ActiveSupport is not available

* Remove extra requires from spec_helper

* Add additional require to Racecar spy

* Update changelog for #1284

Author: jaggederest

CHANGELOG.asciidoc

@@ -43,6 +43,7 @@ endif::[]
 
 - Added transaction_name to reported error to allow grouping by transaction name {pull}1267[#1267]
 - Added ability to query server for version (useful in the future) {pull}1278[#1278]
+- Added instrumentation for https://github.com/zendesk/racecar/ Racecar Kafka library {pull}1284[#1284]
 
 ===== Changed
 

Gemfile

@@ -51,6 +51,7 @@ gem 'json-schema', require: nil
 gem 'mongo', require: nil
 gem 'opentracing', require: nil
 gem 'rake', '>= 13.0', require: nil
+gem 'racecar', require: nil
 gem 'resque', require: nil
 gem 'sequel', require: nil
 gem 'shoryuken', require: nil

lib/elastic_apm/config.rb

@@ -159,6 +159,7 @@ def available_instrumentations
         mongo
         net_http
         rake
+        racecar
         redis
         resque
         s3

lib/elastic_apm/spies/racecar.rb

@@ -0,0 +1,77 @@
+# Licensed to Elasticsearch B.V. under one or more contributor
+# license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright
+# ownership. Elasticsearch B.V. licenses this file to you under
+# the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+begin
+require 'active_support/notifications'
+require 'active_support/subscriber'
+
+  # frozen_string_literal: true
+  module ElasticAPM
+    # @api private
+    module Spies
+      # @api private
+      class RacecarSpy
+        TYPE = 'kafka'
+        SUBTYPE = 'racecar'
+
+        # @api private
+        class ConsumerSubscriber < ActiveSupport::Subscriber
+          def start_process_message(event)
+            start_process_transaction(event: event, kind: 'process_message')
+          end
+          def process_message(_event)
+            ElasticAPM.end_transaction
+          end
+
+          def start_process_batch(event)
+            start_process_transaction(event: event, kind: 'process_batch')
+          end
+          def process_batch(_event)
+            ElasticAPM.end_transaction
+          end
+
+          private # only public methods will be subscribed
+
+          def start_process_transaction(event:, kind:)
+            ElasticAPM.start_transaction(kind, TYPE)
+            ElasticAPM.current_transaction.context.set_service(framework_name: 'racecar', framework_version: Racecar::VERSION)
+          end
+        end
+
+        class ProducerSubscriber < ActiveSupport::Subscriber
+          def start_deliver_message(event)
+            ElasticAPM.start_transaction('deliver_message',TYPE)
+            ElasticAPM.current_transaction.context.set_service(framework_name: 'racecar', framework_version: Racecar::VERSION)
+          end
+
+          def deliver_message(_event)
+            ElasticAPM.end_transaction
+          end
+        end
+
+        def install
+          ConsumerSubscriber.attach_to(:racecar)
+          ProducerSubscriber.attach_to(:racecar)
+        end
+      end
+      register 'Racecar', 'racecar', RacecarSpy.new
+    end
+  end
+
+rescue LoadError
+  # no active support available
+end

spec/elastic_apm/spies/racecar_spec.rb

@@ -0,0 +1,45 @@
+# Licensed to Elasticsearch B.V. under one or more contributor
+# license agreements. See the NOTICE file distributed with
+# this work for additional information regarding copyright
+# ownership. Elasticsearch B.V. licenses this file to you under
+# the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# frozen_string_literal: true
+
+require 'spec_helper'
+
+begin
+  require 'active_support/notifications'
+  require "active_support/subscriber"
+  require 'racecar'
+
+  module ElasticAPM
+    RSpec.describe 'Spy: Racecar', :intercept do
+      it 'captures the instrumentation' do
+        with_agent do
+          ActiveSupport::Notifications.instrument('start_process_message.racecar')
+          ActiveSupport::Notifications.instrument('process_message.racecar') do
+            # this is the body of the racecar consumer #process method
+          end
+          first_transaction = @intercepted.transactions.first
+          expect(first_transaction).not_to be_nil
+          expect(first_transaction.name).to eq('process_message')
+          expect(first_transaction.type).to eq('kafka')
+        end
+      end
+    end
+  end
+
+rescue LoadError # in case we don't have ActiveSupport
+end