Add support for ActiveSupport::EventReporter (#1481)

jeffkreeftmeijer · tombruijn · web-flow · commit 8c55fee2364b · 2025-12-04T16:35:45.000+01:00
* Add Appsignal::Integrations::ActiveSupportEventReporter

Rails 8.1 adds ActiveSupport::EventReporter, an interface for
reporting structured events. To catch these, report them as info-level
logs in the rails_events category through the newly added
Appsignal::Integrations::ActiveSupportEventReporter.

* Update .changesets/report-events-from-rails-8-1-s-activesupport--eventreporter-as-logs.md

Co-authored-by: Tom de Bruijn &lt;tom@tomdebruijn.com&gt;

* Update spec/lib/appsignal/hooks/active_support_event_reporter_spec.rb

Co-authored-by: Tom de Bruijn &lt;tom@tomdebruijn.com&gt;

* Update spec/lib/appsignal/hooks/active_support_event_reporter_spec.rb

Co-authored-by: Tom de Bruijn &lt;tom@tomdebruijn.com&gt;

* Add enable_active_support_event_reporter config

Add a configuration option to allow users to opt out of the
ActiveSupport::EventReporter integration. The option is enabled by
default and can be disabled via
APPSIGNAL_ENABLE_ACTIVE_SUPPORT_EVENT_REPORTER or
enable_active_support_event_reporter.

* Rename enable_active_support_event_reporter config option

Renames the configuration option from
`enable_active_support_event_reporter` to
`enable_active_support_event_log_reporter` to better reflect its
purpose of reporting events as logs.

Changes:
- Updated config default and BOOLEAN_OPTIONS mapping
- Updated environment variable name to
  APPSIGNAL_ENABLE_ACTIVE_SUPPORT_EVENT_LOG_REPORTER
- Updated YARD documentation
- Updated all test fixtures and specs

* Format active_support_event_reporter and tests

* Fix ActiveSupport EventReporter hook for non-Rails apps

The ActiveSupportEventReporterHook was attempting to call
Rails.event.subscribe even in non-Rails environments where Rails
is not defined, causing a NameError that would be logged as an
error during hook installation. This caused test failures when
running the grape gemfile suite.

The fix adds a check for Rails being defined in the
dependencies_present? method, ensuring the hook only attempts to
install in Rails applications where Rails.event is available.

This prevents the hook from trying to install in applications that
use ActiveSupport (like Grape) but don't have Rails defined.

* Update type signatures for new config option

Add enable_active_support_event_log_reporter config option to both
RBI and RBS type signature files.

* Add enable_active_support_event_log_reporter to tests

Add enable_active_support_event_log_reporter configuration option
to the diagnose integration test expectations.

* Fix rubocop line length issues in diagnose spec

Break long regex patterns onto separate lines to fix Layout/LineLength
rubocop offenses.

* Fix ActiveSupport EventReporter hook test for non-Rails apps

Update the test to properly handle the case where ActiveSupport is
loaded without Rails. The test now correctly mocks the event reporter
and its subscribers array to verify the hook installation works in
non-Rails environments.

* Use DependencyHelper for test conditional consistency

Replace the ad-hoc `defined?(::Rails)` check with
`DependencyHelper.rails8_1_present?` to ensure the #install test
block only runs in appropriate Rails 8.1+ environments. This fixes
test failures in JRuby with the no_dependencies gemfile where Rails
may not be properly defined.

* Fix diagnose spec JSON error pattern for JRuby

Update the regex patterns in the diagnose spec to handle JRuby's JSON
parse error messages. JRuby returns "unexpected token at 'invalid..."
with the full invalid content in the quote, while MRI Ruby returns
"unexpected token at 'invalid'" with just the first token.

Changed the pattern from matching a closing quote after 'invalid' to
just matching the word 'invalid', making it compatible with both MRI
Ruby and JRuby error message formats.

---------

Co-authored-by: Tom de Bruijn &lt;tom@tomdebruijn.com&gt;
diff --git a/.changesets/report-events-from-rails-8-1-s-activesupport--eventreporter-as-logs.md b/.changesets/report-events-from-rails-8-1-s-activesupport--eventreporter-as-logs.md
@@ -0,0 +1,6 @@
+---
+bump: minor
+type: add
+---
+
+Report events from Rails 8.1's Structured Event Reporting (`ActiveSupport::EventReporter`) as logs.
diff --git a/lib/appsignal/config.rb b/lib/appsignal/config.rb
@@ -102,6 +102,7 @@ def dsl_config_file?
       :enable_gvl_global_timer => true,
       :enable_gvl_waiting_threads => true,
       :enable_rails_error_reporter => true,
+      :enable_active_support_event_log_reporter => true,
       :enable_rake_performance_instrumentation => false,
       :endpoint => "https://push.appsignal.com",
       :files_world_accessible => true,
@@ -184,6 +185,8 @@ def dsl_config_file?
       :enable_gvl_global_timer => "APPSIGNAL_ENABLE_GVL_GLOBAL_TIMER",
       :enable_gvl_waiting_threads => "APPSIGNAL_ENABLE_GVL_WAITING_THREADS",
       :enable_rails_error_reporter => "APPSIGNAL_ENABLE_RAILS_ERROR_REPORTER",
+      :enable_active_support_event_log_reporter =>
+        "APPSIGNAL_ENABLE_ACTIVE_SUPPORT_EVENT_LOG_REPORTER",
       :enable_rake_performance_instrumentation =>
         "APPSIGNAL_ENABLE_RAKE_PERFORMANCE_INSTRUMENTATION",
       :files_world_accessible => "APPSIGNAL_FILES_WORLD_ACCESSIBLE",
@@ -802,6 +805,8 @@ def activate_if_environment(*envs)
       #   @return [Boolean] Configure whether GVL waiting threads instrumentation is enabled
       # @!attribute [rw] enable_rails_error_reporter
       #   @return [Boolean] Configure whether Rails error reporter integration is enabled
+      # @!attribute [rw] enable_active_support_event_log_reporter
+      #   @return [Boolean] Configure whether ActiveSupport::EventReporter integration is enabled
       # @!attribute [rw] enable_rake_performance_instrumentation
       #   @return [Boolean] Configure whether Rake performance instrumentation is enabled
       # @!attribute [rw] files_world_accessible
diff --git a/lib/appsignal/hooks.rb b/lib/appsignal/hooks.rb
@@ -79,6 +79,7 @@ def truncate(text)
 require "appsignal/hooks/action_mailer"
 require "appsignal/hooks/active_job"
 require "appsignal/hooks/active_support_notifications"
+require "appsignal/hooks/active_support_event_reporter"
 require "appsignal/hooks/celluloid"
 require "appsignal/hooks/code_ownership"
 require "appsignal/hooks/delayed_job"
diff --git a/lib/appsignal/hooks/active_support_event_reporter.rb b/lib/appsignal/hooks/active_support_event_reporter.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module Appsignal
+  class Hooks
+    # @!visibility private
+    class ActiveSupportEventReporterHook < Appsignal::Hooks::Hook
+      register :active_support_event_reporter
+
+      def dependencies_present?
+        defined?(::Rails) &&
+          defined?(::ActiveSupport::EventReporter) &&
+          Appsignal.config &&
+          Appsignal.config[:enable_active_support_event_log_reporter]
+      end
+
+      def install
+        require "appsignal/integrations/active_support_event_reporter"
+        Rails.event.subscribe(Appsignal::Integrations::ActiveSupportEventReporter::Subscriber.new)
+      end
+    end
+  end
+end
diff --git a/lib/appsignal/integrations/active_support_event_reporter.rb b/lib/appsignal/integrations/active_support_event_reporter.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module Appsignal
+  module Integrations
+    # @!visibility private
+    module ActiveSupportEventReporter
+      class Subscriber
+        def initialize
+          @logger = Appsignal::Logger.new("rails_events")
+        end
+
+        def emit(event)
+          @logger.info(event[:name], event[:payload])
+        end
+      end
+    end
+  end
+end
diff --git a/sig/appsignal.rbi b/sig/appsignal.rbi
@@ -1206,6 +1206,10 @@ module Appsignal
       sig { returns(T::Boolean) }
       attr_accessor :enable_rails_error_reporter
 
+      # _@return_ — Configure whether ActiveSupport::EventReporter integration is enabled
+      sig { returns(T::Boolean) }
+      attr_accessor :enable_active_support_event_log_reporter
+
       # _@return_ — Configure whether Rake performance instrumentation is enabled
       sig { returns(T::Boolean) }
       attr_accessor :enable_rake_performance_instrumentation
diff --git a/sig/appsignal.rbs b/sig/appsignal.rbs
@@ -1123,6 +1123,9 @@ module Appsignal
       # _@return_ — Configure whether Rails error reporter integration is enabled
       attr_accessor enable_rails_error_reporter: bool
 
+      # _@return_ — Configure whether ActiveSupport::EventReporter integration is enabled
+      attr_accessor enable_active_support_event_log_reporter: bool
+
       # _@return_ — Configure whether Rake performance instrumentation is enabled
       attr_accessor enable_rake_performance_instrumentation: bool
 
diff --git a/spec/integration/diagnose b/spec/integration/diagnose
@@ -1 +1 @@
-Subproject commit e9ef0aa122b84a0d03946a97f747319317a1c410
+Subproject commit 819d16b7f5bafc1c27d59741e2d421f7f0451990
diff --git a/spec/lib/appsignal/cli/diagnose_spec.rb b/spec/lib/appsignal/cli/diagnose_spec.rb
@@ -490,13 +490,19 @@ def dont_accept_prompt_to_send_diagnostics_report
             "Agent diagnostics",
             "  Error while parsing agent diagnostics report:",
             "    Output: invalid agent\njson"
-          expect(output)
-            .to match(/Error:( \d+:)? unexpected (token at|character:) 'invalid/)
+          # Ruby 3.x / JRuby: "unexpected token at 'invalid...'"
+          # Ruby 4.x: "unexpected character: 'invalid'" or "source is not valid JSON!"
+          error_pattern =
+            /Error:.*(?:unexpected (?:token at|character:) 'invalid|source is not valid JSON!)/
+          expect(output).to match(error_pattern)
         end
 
         it "adds the output to the report" do
-          expect(received_report["agent"]["error"])
-            .to match(/unexpected (token at|character:) 'invalid/)
+          # Ruby 3.x / JRuby: "unexpected token at 'invalid...'"
+          # Ruby 4.x: "unexpected character: 'invalid'" or "source is not valid JSON!"
+          error_pattern =
+            /(?:unexpected (?:token at|character:) 'invalid|source is not valid JSON!)/
+          expect(received_report["agent"]["error"]).to match(error_pattern)
           expect(received_report["agent"]["output"]).to eq(["invalid agent", "json"])
         end
       end
diff --git a/spec/lib/appsignal/config_spec.rb b/spec/lib/appsignal/config_spec.rb
@@ -720,6 +720,7 @@ def on_load
         :enable_minutely_probes => false,
         :enable_nginx_metrics => false,
         :enable_rails_error_reporter => false,
+        :enable_active_support_event_log_reporter => false,
         :enable_rake_performance_instrumentation => false,
         :enable_statsd => false,
         :endpoint => "https://test.appsignal.com",
@@ -792,6 +793,7 @@ def on_load
         "APPSIGNAL_ENABLE_MINUTELY_PROBES" => "false",
         "APPSIGNAL_ENABLE_NGINX_METRICS" => "false",
         "APPSIGNAL_ENABLE_RAILS_ERROR_REPORTER" => "false",
+        "APPSIGNAL_ENABLE_ACTIVE_SUPPORT_EVENT_LOG_REPORTER" => "false",
         "APPSIGNAL_ENABLE_RAKE_PERFORMANCE_INSTRUMENTATION" => "false",
         "APPSIGNAL_ENABLE_STATSD" => "false",
         "APPSIGNAL_FILES_WORLD_ACCESSIBLE" => "false",
@@ -926,6 +928,7 @@ def on_load
         :enable_statsd                  => true,
         :enable_nginx_metrics           => false,
         :enable_rails_error_reporter    => true,
+        :enable_active_support_event_log_reporter => true,
         :enable_rake_performance_instrumentation => false,
         :endpoint                       => "https://push.appsignal.com",
         :files_world_accessible         => true,
diff --git a/spec/lib/appsignal/hooks/active_support_event_reporter_spec.rb b/spec/lib/appsignal/hooks/active_support_event_reporter_spec.rb
@@ -0,0 +1,79 @@
+describe Appsignal::Hooks::ActiveSupportEventReporterHook do
+  begin
+    require "active_support/event_reporter"
+  rescue LoadError # rubocop:disable Lint/SuppressedException
+  end
+
+  describe "#dependencies_present?" do
+    if DependencyHelper.rails8_1_present?
+      context "when ActiveSupport::EventReporter is present" do
+        context "with enable_active_support_event_log_reporter enabled" do
+          before { start_agent }
+
+          it "returns true" do
+            expect(described_class.new.dependencies_present?).to be_truthy
+          end
+        end
+
+        context "with enable_active_support_event_log_reporter disabled" do
+          before do
+            ENV["APPSIGNAL_ENABLE_ACTIVE_SUPPORT_EVENT_LOG_REPORTER"] = "false"
+            start_agent
+          end
+
+          it "returns false" do
+            expect(described_class.new.dependencies_present?).to be_falsy
+          end
+        end
+
+        context "when Rails is not defined" do
+          before do
+            start_agent
+            hide_const("Rails")
+          end
+
+          it "returns false" do
+            expect(described_class.new.dependencies_present?).to be_falsy
+          end
+        end
+      end
+    else
+      context "when ActiveSupport::EventReporter is not present" do
+        subject { described_class.new.dependencies_present? }
+
+        it { is_expected.to be_falsy }
+      end
+    end
+  end
+
+  if DependencyHelper.rails8_1_present?
+    describe "#install" do
+      before do
+        # Mock Rails.event
+        subscribers = []
+        mock_event_reporter = instance_double(
+          "ActiveSupport::EventReporter",
+          :subscribe => nil,
+          :subscribers => subscribers
+        )
+
+        allow(mock_event_reporter).to receive(:subscribe) do |subscriber|
+          subscribers << subscriber
+        end
+
+        allow(Rails).to receive(:event).and_return(mock_event_reporter)
+      end
+
+      it "subscribes the ActiveSupportEventReporter::Subscriber to Rails.event" do
+        event_reporter = Rails.event
+        expect(event_reporter.subscribers).to be_empty
+
+        described_class.new.install
+
+        expect(event_reporter.subscribers.length).to eq(1)
+        expect(event_reporter.subscribers.first)
+          .to be_a(Appsignal::Integrations::ActiveSupportEventReporter::Subscriber)
+      end
+    end
+  end
+end
diff --git a/spec/lib/appsignal/integrations/active_support_event_reporter_spec.rb b/spec/lib/appsignal/integrations/active_support_event_reporter_spec.rb
@@ -0,0 +1,25 @@
+require "appsignal/integrations/active_support_event_reporter"
+
+describe Appsignal::Integrations::ActiveSupportEventReporter::Subscriber do
+  let(:subscriber) { described_class.new }
+  let(:logger) { instance_double(Appsignal::Logger) }
+
+  before do
+    start_agent
+    allow(Appsignal::Logger).to receive(:new).with("rails_events").and_return(logger)
+  end
+
+  describe "#emit" do
+    it "logs the event name and payload" do
+      event = {
+        :name => "user.created",
+        :payload => { :id => 123, :email => "user@example.com" }
+      }
+
+      expect(logger).to receive(:info).with("user.created",
+        { :id => 123, :email => "user@example.com" })
+
+      subscriber.emit(event)
+    end
+  end
+end
diff --git a/spec/support/helpers/dependency_helper.rb b/spec/support/helpers/dependency_helper.rb
@@ -49,6 +49,10 @@ def rails7_1_present?
     rails_present? && rails_version >= Gem::Version.new("7.1.0")
   end
 
+  def rails8_1_present?
+    rails_present? && rails_version >= Gem::Version.new("8.1.0")
+  end
+
   def active_job_wraps_args?
     rails7_present? || (ruby_3_1_or_newer? && rails6_1_present? && !rails6_1_5_present?)
   end
