Merge pull request #43625 from Shopify/error-reporting-api

Rails standardized error reporting interface

actionpack/lib/action_dispatch/middleware/executor.rb

@@ -13,6 +13,9 @@ module ActionDispatch
       begin
         response = @app.call(env)
         returned = response << ::Rack::BodyProxy.new(response.pop) { state.complete! }
+      rescue => error
+        @executor.error_reporter.report(error, handled: false)
+        raise
       ensure
         state.complete! unless returned
       end

activesupport/lib/active_support.rb

@@ -43,6 +43,7 @@ module ActiveSupport
   autoload :ExecutionContext
   autoload :ExecutionWrapper
   autoload :Executor
+  autoload :ErrorReporter
   autoload :FileUpdateChecker
   autoload :EventedFileUpdateChecker
   autoload :ForkTracker

activesupport/lib/active_support/error_reporter.rb

@@ -0,0 +1,109 @@
+# frozen_string_literal: true
+
+module ActiveSupport
+  # +ActiveSupport::ErrorReporter+ is a common interface for error reporting services.
+  #
+  # To rescue and report any unhandled error, you can use the +handle+ method:
+  #
+  #   Rails.error.handle do
+  #     do_something!
+  #   end
+  #
+  # If an error is raised, it will be reported and swallowed.
+  #
+  # Alternatively if you want to report the error but not swallow it, you can use `record`
+  #
+  #   Rails.error.record do
+  #     do_something!
+  #   end
+  #
+  # Both methods can be restricted to only handle a specific exception class
+  #
+  #  maybe_tags = Rails.error.handle(Redis::BaseError) { redis.get("tags) }
+  #
+  # You can also pass some extra context information that may be used by the error subscribers:
+  #
+  #  Rails.error.handle(context: { section: "admin" }) do
+  #    # ...
+  #  end
+  #
+  # Additionally a +severity+ can be passed along to communicate how important the error report is.
+  # +severity+ can be one of +:error+, +:warning+ or +:info+. Handled errors default to the +:warning+
+  # severity, and unhandled ones to +error+.
+  class ErrorReporter
+    SEVERITIES = %i(error warning info)
+
+    attr_accessor :logger
+
+    def initialize(*subscribers, logger: nil)
+      @subscribers = subscribers.flatten
+      @logger = logger
+    end
+
+    # Report any unhandled exception, and swallow it.
+    #
+    #  Rails.error.handle do
+    #    1 + '1'
+    #  end
+    #
+    def handle(error_class = StandardError, severity: :warning, context: {})
+      yield
+    rescue error_class => error
+      report(error, handled: true, severity: severity, context: context)
+      nil
+    end
+
+    def record(error_class = StandardError, severity: :error, context: {})
+      yield
+    rescue error_class => error
+      report(error, handled: false, severity: severity, context: context)
+      raise
+    end
+
+    # Register a new error subscriber. The subscriber must respond to
+    #
+    #   report(Exception, handled: Boolean, context: Hash)
+    #
+    # The +report+ method +should+ never raise an error.
+    def subscribe(subscriber)
+      unless subscriber.respond_to?(:report)
+        raise ArgumentError, "Error subscribers must respond to #report"
+      end
+      @subscribers << subscriber
+    end
+
+    # Update the execution context that is accessible to error subscribers
+    #
+    #   Rails.error.set_context(section: "checkout", user_id: @user.id)
+    #
+    # See +ActiveSupport::ExecutionContext.set+
+    def set_context(...)
+      ActiveSupport::ExecutionContext.set(...)
+    end
+
+    # When the block based +handle+ and +record+ methods are not suitable, you can directly use +report+
+    #
+    #  Rails.error.report(error, handled: true)
+    def report(error, handled:, severity: handled ? :warning : :error, context: {})
+      unless SEVERITIES.include?(severity)
+        raise ArgumentError, "severity must be one of #{SEVERITIES.map(&:inspect).join(", ")}, got: #{severity.inspect}"
+      end
+
+      full_context = ActiveSupport::ExecutionContext.to_h.merge(context)
+      @subscribers.each do |subscriber|
+        subscriber.report(error, handled: handled, severity: severity, context: full_context)
+      rescue => subscriber_error
+        if logger
+          logger.fatal(
+            "Error subscriber raised an error: #{subscriber_error.message} (#{subscriber_error.class})\n" +
+            subscriber_error.backtrace.join("\n")
+          )
+        else
+          raise
+        end
+      end
+
+      nil
+    end
+  end
+end

activesupport/lib/active_support/execution_wrapper.rb

@@ -1,5 +1,6 @@
 # frozen_string_literal: true
 
+require "active_support/error_reporter"
 require "active_support/callbacks"
 require "concurrent/hash"
 
@@ -86,6 +87,9 @@ module ActiveSupport
       instance = run!
       begin
         yield
+      rescue => error
+        error_reporter.report(error, handled: false)
+        raise
       ensure
         instance.complete!
       end
@@ -105,6 +109,10 @@ module ActiveSupport
       attr_accessor :active
     end
 
+    def self.error_reporter
+      @error_reporter ||= ActiveSupport::ErrorReporter.new
+    end
+
     def self.inherited(other) # :nodoc:
       super
       other.active = Concurrent::Hash.new

activesupport/test/error_reporter_test.rb

@@ -0,0 +1,131 @@
+# frozen_string_literal: true
+
+require_relative "abstract_unit"
+require "active_support/execution_context/test_helper"
+
+class ErrorReporterTest < ActiveSupport::TestCase
+  # ExecutionContext is automatically reset in Rails app via executor hooks set in railtie
+  # But not in Active Support's own test suite.
+  include ActiveSupport::ExecutionContext::TestHelper
+
+  class ErrorSubscriber
+    attr_reader :events
+
+    def initialize
+      @events = []
+    end
+
+    def report(error, handled:, severity:, context:)
+      @events << [error, handled, severity, context]
+    end
+  end
+
+  setup do
+    @reporter = ActiveSupport::ErrorReporter.new
+    @subscriber = ErrorSubscriber.new
+    @reporter.subscribe(@subscriber)
+    @error = ArgumentError.new("Oops")
+  end
+
+  test "receives the execution context" do
+    @reporter.set_context(section: "admin")
+    error = ArgumentError.new("Oops")
+    @reporter.report(error, handled: true)
+    assert_equal [[error, true, :warning, { section: "admin" }]], @subscriber.events
+  end
+
+  test "passed context has priority over the execution context" do
+    @reporter.set_context(section: "admin")
+    error = ArgumentError.new("Oops")
+    @reporter.report(error, handled: true, context: { section: "public" })
+    assert_equal [[error, true, :warning, { section: "public" }]], @subscriber.events
+  end
+
+  test "#handle swallow and report any unhandled error" do
+    error = ArgumentError.new("Oops")
+    @reporter.handle do
+      raise error
+    end
+    assert_equal [[error, true, :warning, {}]], @subscriber.events
+  end
+
+  test "#handle can be scoped to an exception class" do
+    assert_raises ArgumentError do
+      @reporter.handle(NameError) do
+        raise ArgumentError
+      end
+    end
+    assert_equal [], @subscriber.events
+  end
+
+  test "#record report any unhandled error and re-raise them" do
+    error = ArgumentError.new("Oops")
+    assert_raises ArgumentError do
+      @reporter.record do
+        raise error
+      end
+    end
+    assert_equal [[error, false, :error, {}]], @subscriber.events
+  end
+
+  test "#record can be scoped to an exception class" do
+    assert_raises ArgumentError do
+      @reporter.record(NameError) do
+        raise ArgumentError
+      end
+    end
+    assert_equal [], @subscriber.events
+  end
+
+  test "can have multiple subscribers" do
+    second_subscriber = ErrorSubscriber.new
+    @reporter.subscribe(second_subscriber)
+
+    error = ArgumentError.new("Oops")
+    @reporter.report(error, handled: true)
+
+    assert_equal 1, @subscriber.events.size
+    assert_equal 1, second_subscriber.events.size
+  end
+
+  test "handled errors default to :warning severity" do
+    @reporter.report(@error, handled: true)
+    assert_equal :warning, @subscriber.events.dig(0, 2)
+  end
+
+  test "unhandled errors default to :error severity" do
+    @reporter.report(@error, handled: false)
+    assert_equal :error, @subscriber.events.dig(0, 2)
+  end
+
+  class FailingErrorSubscriber
+    Error = Class.new(StandardError)
+
+    def initialize(error)
+      @error = error
+    end
+
+    def report(_error, handled:, severity:, context:)
+      raise @error
+    end
+  end
+
+  test "subscriber errors are re-raised if no logger is set" do
+    subscriber_error = FailingErrorSubscriber::Error.new("Big Oopsie")
+    @reporter.subscribe(FailingErrorSubscriber.new(subscriber_error))
+    assert_raises FailingErrorSubscriber::Error do
+      @reporter.report(@error, handled: true)
+    end
+  end
+
+  test "subscriber errors are logged if a logger is set" do
+    subscriber_error = FailingErrorSubscriber::Error.new("Big Oopsie")
+    @reporter.subscribe(FailingErrorSubscriber.new(subscriber_error))
+    log = StringIO.new
+    @reporter.logger = ActiveSupport::Logger.new(log)
+    @reporter.report(@error, handled: true)
+
+    expected = "Error subscriber raised an error: Big Oopsie (ErrorReporterTest::FailingErrorSubscriber::Error)"
+    assert_equal expected, log.string.lines.first.chomp
+  end
+end

activesupport/test/executor_test.rb

@@ -6,6 +6,30 @@ class ExecutorTest < ActiveSupport::TestCase
   class DummyError < RuntimeError
   end
 
+  class ErrorSubscriber
+    attr_reader :events
+
+    def initialize
+      @events = []
+    end
+
+    def report(error, handled:, severity:, context:)
+      @events << [error, handled, severity, context]
+    end
+  end
+
+  def test_wrap_report_errors
+    subscriber = ErrorSubscriber.new
+    executor.error_reporter.subscribe(subscriber)
+    error = DummyError.new("Oops")
+    assert_raises DummyError do
+      executor.wrap do
+        raise error
+      end
+    end
+    assert_equal [[error, false, :error, {}]], subscriber.events
+  end
+
   def test_wrap_invokes_callbacks
     called = []
     executor.to_run { called << :run }

railties/lib/rails.rb

@@ -81,6 +81,10 @@ module Rails
       @_env = ActiveSupport::EnvironmentInquirer.new(environment)
     end
 
+    def error
+      application && application.executor.error_reporter
+    end
+
     # Returns all Rails groups for loading based on:
     #
     # * The Rails environment;

railties/lib/rails/application/bootstrap.rb

@@ -49,8 +49,11 @@ module Rails
           )
           logger
         end
-
         Rails.logger.level = ActiveSupport::Logger.const_get(config.log_level.to_s.upcase)
+
+        unless config.consider_all_requests_local
+          Rails.error.logger = Rails.logger
+        end
       end
 
       # Initialize cache early in the stack so railties can make use of it.