add action mailer instrumentation

docs/GettingStarted.md

@@ -494,6 +494,7 @@ Where `options` is an optional `Hash` that accepts the following parameters:
 | --- | ----------- | ------- |
 | `analytics_enabled` | Enable analytics for spans produced by this integration. `true` for on, `nil` to defer to global setting, `false` for off. | `false` |
 | `service_name` | Service name used for `action_mailer` instrumentation | `'action_mailer'` |
+| `email_data` | Whether or not to append additional email payload metadata to `action_mailer.deliver` spans. Fields include `['subject', 'to', 'from', 'bcc', 'cc', 'date', 'perform_deliveries']`. | `false` |
 
 ### Active Model Serializers
 

lib/ddtrace/contrib/action_mailer/configuration/settings.rb

@@ -23,6 +23,7 @@ class Settings < Contrib::Configuration::Settings
           end
 
           option :service_name, default: Ext::SERVICE_NAME
+          option :email_data, default: false
         end
       end
     end

lib/ddtrace/contrib/action_mailer/events/deliver.rb

@@ -32,6 +32,19 @@ def process(span, event, _id, payload)
             span.span_type = span_type
             span.set_tag(Ext::TAG_MAILER, payload[:mailer])
             span.set_tag(Ext::TAG_MSG_ID, payload[:message_id])
+
+            # Since email date can contain PII we disable by default
+            # Some of these fields can be either strings or arrays, so we try to normalize
+            # https://github.com/rails/rails/blob/18707ab17fa492eb25ad2e8f9818a320dc20b823/actionmailer/lib/action_mailer/base.rb#L742-L754
+            if configuration[:email_data] == true
+              span.set_tag(Ext::TAG_SUBJECT, payload[:subject].to_s) if payload[:subject]
+              span.set_tag(Ext::TAG_TO, payload[:to].join(',')) if payload[:to]
+              span.set_tag(Ext::TAG_FROM, payload[:from].join(',')) if payload[:from]
+              span.set_tag(Ext::TAG_BCC, payload[:bcc].join(',')) if payload[:bcc]
+              span.set_tag(Ext::TAG_CC, payload[:cc].join(',')) if payload[:cc]
+              span.set_tag(Ext::TAG_DATE, payload[:date].to_s) if payload[:date]
+              span.set_tag(Ext::TAG_PERFORM_DELIVERIES, payload[:perform_deliveries]) if payload[:perform_deliveries]
+            end
           end
         end
       end

lib/ddtrace/contrib/action_mailer/ext.rb

@@ -17,6 +17,14 @@ module Ext
         TAG_ACTION = 'action_mailer.action'.freeze
         TAG_MAILER = 'action_mailer.mailer'.freeze
         TAG_MSG_ID = 'action_mailer.message_id'.freeze
+
+        TAG_SUBJECT = 'action_mailer.subject'.freeze
+        TAG_TO = 'action_mailer.to'.freeze
+        TAG_FROM = 'action_mailer.from'.freeze
+        TAG_BCC = 'action_mailer.bcc'.freeze
+        TAG_CC = 'action_mailer.cc'.freeze
+        TAG_DATE = 'action_mailer.date'.freeze
+        TAG_PERFORM_DELIVERIES = 'action_mailer.perform_deliveries'.freeze
       end
     end
   end

spec/ddtrace/contrib/action_mailer/helpers.rb

@@ -20,7 +20,11 @@
         default from: 'test@example.com'
 
         def test_mail(_arg)
-          mail(to: 'test@example.com', body: 'sk test')
+          mail(to: 'test@example.com',
+               body: 'sk test',
+               subject: 'miniswan',
+               bcc: 'test_a@example.com,test_b@example.com',
+               cc: ['test_c@example.com', 'test_d@example.com'])
         end
       end
     )

spec/ddtrace/contrib/action_mailer/patcher_spec.rb

@@ -86,5 +86,26 @@
 
       it_behaves_like 'measured span for integration', true
     end
+
+    context 'with email_data enabled' do
+      let(:configuration_options) { { email_data: true } }
+
+      it 'is expected to add additional email date to deliver span' do
+        expect(deliver_span).to_not be nil
+        expect(deliver_span.service).to eq('action_mailer')
+        expect(deliver_span.name).to eq('action_mailer.deliver')
+        expect(deliver_span.resource).to eq(mailer)
+        expect(deliver_span.get_tag('action_mailer.mailer')).to eq(mailer)
+        expect(deliver_span.span_type).to eq('worker')
+        expect(deliver_span.get_tag('action_mailer.message_id')).to_not be nil
+        expect(deliver_span.status).to_not eq(Datadog::Ext::Errors::STATUS)
+
+        expect(deliver_span.get_tag('action_mailer.to')).to eq('test@example.com')
+        expect(deliver_span.get_tag('action_mailer.from')).to eq('test@example.com')
+        expect(deliver_span.get_tag('action_mailer.subject')).to eq('miniswan')
+        expect(deliver_span.get_tag('action_mailer.bcc')).to eq('test_a@example.com,test_b@example.com')
+        expect(deliver_span.get_tag('action_mailer.cc')).to eq('test_c@example.com,test_d@example.com')
+      end
+    end
   end
 end