add action mailer instrumentation

Rakefile

@@ -108,6 +108,7 @@ namespace :spec do
   # Datadog Tracing integrations
   [
     :action_cable,
+    :action_mailer,
     :action_pack,
     :action_view,
     :active_model_serializers,
@@ -585,12 +586,15 @@ task :ci do
     declare 'bundle exec appraisal rails6-semantic-logger rake spec:railssemanticlogger'
     declare 'bundle exec appraisal rails61-semantic-logger rake spec:railssemanticlogger'
     declare 'bundle exec appraisal rails5-mysql2 rake spec:action_cable'
+    declare 'bundle exec appraisal rails5-mysql2 rake spec:action_mailer'
     declare 'bundle exec appraisal rails5-mysql2 rake spec:rails'
     declare 'bundle exec appraisal rails5-postgres rake spec:rails'
     declare 'bundle exec appraisal rails6-mysql2 rake spec:action_cable'
+    declare 'bundle exec appraisal rails6-mysql2 rake spec:action_mailer'
     declare 'bundle exec appraisal rails6-mysql2 rake spec:rails'
     declare 'bundle exec appraisal rails6-postgres rake spec:rails'
     declare 'bundle exec appraisal rails61-mysql2 rake spec:action_cable'
+    declare 'bundle exec appraisal rails61-mysql2 rake spec:action_mailer'
     declare 'bundle exec appraisal rails61-mysql2 rake spec:rails'
     declare 'bundle exec appraisal rails61-postgres rake spec:rails'
     declare 'bundle exec appraisal rails61-postgres rake spec:railsdisableenv'
@@ -679,12 +683,15 @@ task :ci do
       declare 'bundle exec appraisal rails6-semantic-logger rake spec:railssemanticlogger'
       declare 'bundle exec appraisal rails61-semantic-logger rake spec:railssemanticlogger'
       declare 'bundle exec appraisal rails5-mysql2 rake spec:action_cable'
+      declare 'bundle exec appraisal rails5-mysql2 rake spec:action_mailer'
       declare 'bundle exec appraisal rails5-mysql2 rake spec:rails'
       declare 'bundle exec appraisal rails5-postgres rake spec:rails'
       declare 'bundle exec appraisal rails6-mysql2 rake spec:action_cable'
+      declare 'bundle exec appraisal rails6-mysql2 rake spec:action_mailer'
       declare 'bundle exec appraisal rails6-mysql2 rake spec:rails'
       declare 'bundle exec appraisal rails6-postgres rake spec:rails'
       declare 'bundle exec appraisal rails61-mysql2 rake spec:action_cable'
+      declare 'bundle exec appraisal rails61-mysql2 rake spec:action_mailer'
       declare 'bundle exec appraisal rails61-mysql2 rake spec:rails'
       declare 'bundle exec appraisal rails61-postgres rake spec:rails'
       declare 'bundle exec appraisal rails61-postgres rake spec:railsdisableenv'
@@ -776,9 +783,11 @@ task :ci do
       declare 'bundle exec appraisal rails5-mysql2 rake spec:rails'
       declare 'bundle exec appraisal rails5-postgres rake spec:rails'
       declare 'bundle exec appraisal rails6-mysql2 rake spec:action_cable'
+      declare 'bundle exec appraisal rails6-mysql2 rake spec:action_mailer'
       declare 'bundle exec appraisal rails6-mysql2 rake spec:rails'
       declare 'bundle exec appraisal rails6-postgres rake spec:rails'
       declare 'bundle exec appraisal rails61-mysql2 rake spec:action_cable'
+      declare 'bundle exec appraisal rails61-mysql2 rake spec:action_mailer'
       declare 'bundle exec appraisal rails61-mysql2 rake spec:rails'
       declare 'bundle exec appraisal rails61-postgres rake spec:rails'
       declare 'bundle exec appraisal rails61-postgres rake spec:railsdisableenv'
@@ -852,6 +861,7 @@ task :ci do
 
       # Rails
       declare 'bundle exec appraisal rails61-mysql2 rake spec:action_cable'
+      declare 'bundle exec appraisal rails61-mysql2 rake spec:action_mailer'
       declare 'bundle exec appraisal rails61-mysql2 rake spec:rails'
       declare 'bundle exec appraisal rails61-postgres rake spec:rails'
       declare 'bundle exec appraisal rails61-postgres rake spec:railsdisableenv'

docs/GettingStarted.md

@@ -28,6 +28,7 @@ To contribute, check out the [contribution guidelines][contribution docs] and [d
  - [Integration instrumentation](#integration-instrumentation)
      - [Action Cable](#action-cable)
      - [Action View](#action-view)
+     - [Action Mailer](#action-mailer)
      - [Active Model Serializers](#active-model-serializers)
      - [Action Pack](#action-pack)
      - [Active Job](#active-job)
@@ -389,6 +390,7 @@ For a list of available integrations, and their configuration options, please re
 | Name                     | Key                        | Versions Supported: MRI  | Versions Supported: JRuby | How to configure                    | Gem source                                                                     |
 | ------------------------ | -------------------------- | ------------------------ | --------------------------| ----------------------------------- | ------------------------------------------------------------------------------ |
 | Action Cable             | `action_cable`             | `>= 5.0`                 | `>= 5.0`                  | *[Link](#action-cable)*             | *[Link](https://github.com/rails/rails/tree/master/actioncable)*               |
+| Action Mailer            | `action_mailer`            | `>= 5.0`                 | `>= 5.0`                  | *[Link](#action-mailer)*            | *[Link](https://github.com/rails/rails/tree/master/actionmailer)*              |
 | Action View              | `action_view`              | `>= 3.0`                 | `>= 3.0`                  | *[Link](#action-view)*              | *[Link](https://github.com/rails/rails/tree/master/actionview)*                |
 | Active Model Serializers | `active_model_serializers` | `>= 0.9`                 | `>= 0.9`                  | *[Link](#active-model-serializers)* | *[Link](https://github.com/rails-api/active_model_serializers)*                |
 | Action Pack              | `action_pack`              | `>= 3.0`                 | `>= 3.0`                  | *[Link](#action-pack)*              | *[Link](https://github.com/rails/rails/tree/master/actionpack)*                |
@@ -397,7 +399,7 @@ For a list of available integrations, and their configuration options, please re
 | Active Support           | `active_support`           | `>= 3.0`                 | `>= 3.0`                  | *[Link](#active-support)*           | *[Link](https://github.com/rails/rails/tree/master/activesupport)*             |
 | AWS                      | `aws`                      | `>= 2.0`                 | `>= 2.0`                  | *[Link](#aws)*                      | *[Link](https://github.com/aws/aws-sdk-ruby)*                                  |
 | Concurrent Ruby          | `concurrent_ruby`          | `>= 0.9`                 | `>= 0.9`                  | *[Link](#concurrent-ruby)*          | *[Link](https://github.com/ruby-concurrency/concurrent-ruby)*                  |
-| Cucumber                 | `cucumber`                 | `>= 3.0`                 | `>= 1.7.16`               | *[Link](#cucumber)*                | *[Link](https://github.com/cucumber/cucumber-ruby)*                            |
+| Cucumber                 | `cucumber`                 | `>= 3.0`                 | `>= 1.7.16`               | *[Link](#cucumber)*                 | *[Link](https://github.com/cucumber/cucumber-ruby)*                            |
 | Dalli                    | `dalli`                    | `>= 2.0`                 | `>= 2.0`                  | *[Link](#dalli)*                    | *[Link](https://github.com/petergoldstein/dalli)*                              |
 | DelayedJob               | `delayed_job`              | `>= 4.1`                 | `>= 4.1`                  | *[Link](#delayedjob)*               | *[Link](https://github.com/collectiveidea/delayed_job)*                        |
 | Elasticsearch            | `elasticsearch`            | `>= 1.0`                 | `>= 1.0`                  | *[Link](#elasticsearch)*            | *[Link](https://github.com/elastic/elasticsearch-ruby)*                        |
@@ -473,6 +475,27 @@ Where `options` is an optional `Hash` that accepts the following parameters:
 | `service_name` | Service name used for rendering instrumentation. | `action_view` |
 | `template_base_path` | Used when the template name is parsed. If you don't store your templates in the `views/` folder, you may need to change this value | `'views/'` |
 
+### Action Mailer
+
+The Action Mailer integration provides tracing for Rails 5 ActionMailer actions.
+
+You can enable it through `Datadog.configure`:
+
+```ruby
+require 'ddtrace'
+ Datadog.configure do |c|
+  c.use :action_mailer, options
+end
+```
+
+Where `options` is an optional `Hash` that accepts the following parameters:
+
+| Key | Description | Default |
+| --- | ----------- | ------- |
+| `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
 
 The Active Model Serializers integration traces the `serialize` event for version 0.9+ and the `render` event for version 0.10+.

lib/datadog/contrib.rb

@@ -26,6 +26,7 @@ module Contrib
 end
 
 require 'ddtrace/contrib/action_cable/integration'
+require 'ddtrace/contrib/action_mailer/integration'
 require 'ddtrace/contrib/action_pack/integration'
 require 'ddtrace/contrib/action_view/integration'
 require 'ddtrace/contrib/active_model_serializers/integration'

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

@@ -0,0 +1,31 @@
+require 'ddtrace/contrib/configuration/settings'
+require 'ddtrace/contrib/action_mailer/ext'
+
+module Datadog
+  module Contrib
+    module ActionMailer
+      module Configuration
+        # Custom settings for the ActionMailer integration
+        class Settings < Contrib::Configuration::Settings
+          option :enabled do |o|
+            o.default { env_to_bool(Ext::ENV_ENABLED, true) }
+            o.lazy
+          end
+
+          option :analytics_enabled do |o|
+            o.default { env_to_bool([Ext::ENV_ANALYTICS_ENABLED, Ext::ENV_ANALYTICS_ENABLED_OLD], false) }
+            o.lazy
+          end
+
+          option :analytics_sample_rate do |o|
+            o.default { env_to_float([Ext::ENV_ANALYTICS_SAMPLE_RATE, Ext::ENV_ANALYTICS_SAMPLE_RATE_OLD], 1.0) }
+            o.lazy
+          end
+
+          option :service_name, default: Ext::SERVICE_NAME
+          option :email_data, default: false
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/action_mailer/event.rb

@@ -0,0 +1,49 @@
+require 'ddtrace/contrib/analytics'
+require 'ddtrace/contrib/active_support/notifications/event'
+require 'ddtrace/contrib/action_mailer/ext'
+
+module Datadog
+  module Contrib
+    module ActionMailer
+      # Defines basic behaviors for an ActionMailer event.
+      module Event
+        def self.included(base)
+          base.send(:include, ActiveSupport::Notifications::Event)
+          base.send(:extend, ClassMethods)
+        end
+
+        # Class methods for ActionMailer events.
+        module ClassMethods
+          def span_options
+            { service: configuration[:service_name] }
+          end
+
+          def tracer
+            -> { configuration[:tracer] }
+          end
+
+          def configuration
+            Datadog.configuration[:action_mailer]
+          end
+
+          def process(span, event, _id, payload)
+            span.service = configuration[:service_name]
+            span.resource = payload[:mailer]
+
+            # Set analytics sample rate
+            if Contrib::Analytics.enabled?(configuration[:analytics_enabled])
+              Contrib::Analytics.set_sample_rate(span, configuration[:analytics_sample_rate])
+            end
+
+            # Measure service stats
+            Contrib::Analytics.set_measured(span)
+
+            report_if_exception(span, payload)
+          rescue StandardError => e
+            Datadog.logger.debug(e.message)
+          end
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/action_mailer/events.rb

@@ -0,0 +1,30 @@
+require 'ddtrace/contrib/action_mailer/events/process'
+require 'ddtrace/contrib/action_mailer/events/deliver'
+
+module Datadog
+  module Contrib
+    module ActionMailer
+      # Defines collection of instrumented ActionMailer events
+      module Events
+        ALL = [
+          Events::Process,
+          Events::Deliver
+        ].freeze
+
+        module_function
+
+        def all
+          self::ALL
+        end
+
+        def subscriptions
+          all.collect(&:subscriptions).collect(&:to_a).flatten
+        end
+
+        def subscribe!
+          all.each(&:subscribe!)
+        end
+      end
+    end
+  end
+end

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

@@ -0,0 +1,53 @@
+require 'ddtrace/contrib/action_mailer/ext'
+require 'ddtrace/contrib/action_mailer/event'
+
+module Datadog
+  module Contrib
+    module ActionMailer
+      module Events
+        # Defines instrumentation for process.action_mailer event
+        module Deliver
+          include ActionMailer::Event
+
+          EVENT_NAME = 'deliver.action_mailer'.freeze
+
+          module_function
+
+          def event_name
+            self::EVENT_NAME
+          end
+
+          def span_name
+            Ext::SPAN_DELIVER
+          end
+
+          def span_type
+            # deliver.action_mailer sends emails
+            Datadog::Ext::AppTypes::WORKER
+          end
+
+          def process(span, event, _id, payload)
+            super
+
+            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
+    end
+  end
+end

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

@@ -0,0 +1,40 @@
+require 'ddtrace/contrib/action_mailer/ext'
+require 'ddtrace/contrib/action_mailer/event'
+
+module Datadog
+  module Contrib
+    module ActionMailer
+      module Events
+        # Defines instrumentation for process.action_mailer event
+        module Process
+          include ActionMailer::Event
+
+          EVENT_NAME = 'process.action_mailer'.freeze
+
+          module_function
+
+          def event_name
+            self::EVENT_NAME
+          end
+
+          def span_name
+            Ext::SPAN_PROCESS
+          end
+
+          def span_type
+            # process.action_mailer processes email and renders partial templates
+            Datadog::Ext::HTTP::TEMPLATE
+          end
+
+          def process(span, event, _id, payload)
+            super
+
+            span.span_type = span_type
+            span.set_tag(Ext::TAG_ACTION, payload[:action])
+            span.set_tag(Ext::TAG_MAILER, payload[:mailer])
+          end
+        end
+      end
+    end
+  end
+end

lib/ddtrace/contrib/action_mailer/ext.rb

@@ -0,0 +1,31 @@
+module Datadog
+  module Contrib
+    module ActionMailer
+      # ActionMailer integration constants
+      module Ext
+        APP = 'action_mailer'.freeze
+        ENV_ENABLED = 'DD_TRACE_ACTION_MAILER_ENABLED'.freeze
+        ENV_ANALYTICS_ENABLED = 'DD_TRACE_ACTION_MAILER_ANALYTICS_ENABLED'.freeze
+        ENV_ANALYTICS_SAMPLE_RATE = 'DD_TRACE_ACTION_MAILER_ANALYTICS_SAMPLE_RATE'.freeze
+
+        ENV_ANALYTICS_ENABLED_OLD = 'DD_ACTION_MAILER_ANALYTICS_ENABLED'.freeze
+
+        ENV_ANALYTICS_SAMPLE_RATE_OLD = 'DD_ACTION_MAILER_ANALYTICS_SAMPLE_RATE'.freeze
+        SERVICE_NAME = 'action_mailer'.freeze
+        SPAN_PROCESS = 'action_mailer.process'.freeze
+        SPAN_DELIVER = 'action_mailer.deliver'.freeze
+        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
+end