Rails structured log subscriber

CHANGELOG.md

@@ -3,6 +3,7 @@
 ### Feature
 
 - Propagated sampling rates as specified in [Traces](https://develop.sentry.dev/sdk/telemetry/traces/#propagated-random-value) docs ([#2671](https://github.com/getsentry/sentry-ruby/pull/2671))
+- Support for defining custom Rails log subscribers that work with Sentry Structured Logging ([#2689](https://github.com/getsentry/sentry-ruby/pull/2689))
 
 ### Internal
 

sentry-rails/lib/sentry/rails/log_subscriber.rb

@@ -0,0 +1,70 @@
+# frozen_string_literal: true
+
+require "active_support/log_subscriber"
+
+module Sentry
+  module Rails
+    # Base class for Sentry log subscribers that extends ActiveSupport::LogSubscriber
+    # to provide structured logging capabilities for Rails components.
+    #
+    # This class follows Rails' LogSubscriber pattern and provides common functionality
+    # for capturing Rails instrumentation events and logging them through Sentry's
+    # structured logging system.
+    #
+    # @example Creating a custom log subscriber
+    #   class MySubscriber < Sentry::Rails::LogSubscriber
+    #     attach_to :my_component
+    #
+    #     def my_event(event)
+    #       log_structured_event(
+    #         message: "My event occurred",
+    #         level: :info,
+    #         attributes: {
+    #           duration_ms: event.duration,
+    #           custom_data: event.payload[:custom_data]
+    #         }
+    #       )
+    #     end
+    #   end
+    class LogSubscriber < ActiveSupport::LogSubscriber
+      class << self
+        if ::Rails.version.to_f < 6.0
+          # Rails 5.x does not provide detach_from
+          def detach_from(namespace, notifications = ActiveSupport::Notifications)
+            listeners = public_instance_methods(false)
+              .flat_map { |key|
+                notifications.notifier.listeners_for("#{key}.#{namespace}")
+              }
+              .select { |listener| listener.instance_variable_get(:@delegate).is_a?(self) }
+
+            listeners.map do |listener|
+              notifications.notifier.unsubscribe(listener)
+            end
+          end
+        end
+      end
+
+      protected
+
+      # Log a structured event using Sentry's structured logger
+      #
+      # @param message [String] The log message
+      # @param level [Symbol] The log level (:trace, :debug, :info, :warn, :error, :fatal)
+      # @param attributes [Hash] Additional structured attributes to include
+      def log_structured_event(message:, level: :info, attributes: {})
+        Sentry.logger.public_send(level, message, **attributes)
+      rescue => e
+        # Silently handle any errors in logging to avoid breaking the application
+        Sentry.configuration.sdk_logger.debug("Failed to log structured event: #{e.message}")
+      end
+
+      # Calculate duration in milliseconds from an event
+      #
+      # @param event [ActiveSupport::Notifications::Event] The event
+      # @return [Float] Duration in milliseconds
+      def duration_ms(event)
+        event.duration.round(2)
+      end
+    end
+  end
+end

sentry-rails/lib/sentry/rails/log_subscribers/parameter_filter.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+module Sentry
+  module Rails
+    module LogSubscribers
+      # Shared utility module for filtering sensitive parameters in log subscribers.
+      #
+      # This module provides consistent parameter filtering across all Sentry Rails
+      # log subscribers, leveraging Rails' built-in parameter filtering when available.
+      # It automatically detects the correct Rails parameter filtering API based on
+      # the Rails version and includes the appropriate implementation module.
+      #
+      # @example Usage in a log subscriber
+      #   class MySubscriber < Sentry::Rails::LogSubscriber
+      #     include Sentry::Rails::LogSubscribers::ParameterFilter
+      #
+      #     def my_event(event)
+      #       if Sentry.configuration.send_default_pii && event.payload[:params]
+      #         filtered_params = filter_sensitive_params(event.payload[:params])
+      #         attributes[:params] = filtered_params unless filtered_params.empty?
+      #       end
+      #     end
+      #   end
+      module ParameterFilter
+        EMPTY_HASH = {}.freeze
+
+        if ::Rails.version.to_f >= 6.0
+          def self.backend
+            ActiveSupport::ParameterFilter
+          end
+        else
+          def self.backend
+            ActionDispatch::Http::ParameterFilter
+          end
+        end
+
+        # Filter sensitive parameters from a hash, respecting Rails configuration.
+        #
+        # @param params [Hash] The parameters to filter
+        # @return [Hash] Filtered parameters with sensitive data removed
+        def filter_sensitive_params(params)
+          return EMPTY_HASH unless params.is_a?(Hash)
+
+          filter_parameters = ::Rails.application.config.filter_parameters
+          parameter_filter = ParameterFilter.backend.new(filter_parameters)
+
+          parameter_filter.filter(params)
+        end
+      end
+    end
+  end
+end

sentry-rails/spec/dummy/test_rails_app/app.rb

@@ -71,6 +71,17 @@ def self.name
 
   configure_app(app)
 
+  # Configure parameter filtering for consistent test behavior
+  app.config.filter_parameters.concat(
+    [:custom_secret,
+     :api_key,
+     :credit_card,
+     :authorization,
+     :password,
+     :token]
+  )
+  app.config.filter_parameters.uniq!
+
   app.routes.append do
     get "/exception", to: "hello#exception"
     get "/view_exception", to: "hello#view_exception"