feat(logging): auto-enable structured_logging

When config.enable_logs is true, enable structured
logging in Rails automatically too.

Closes #2715

Author: solnic

CHANGELOG.md

@@ -3,6 +3,33 @@
 ### Features
 
 - Support for `:origin` attribute in log events ([#2712](https://github.com/getsentry/sentry-ruby/pull/2712))
+- Auto-enable Rails structured logging when `enable_logs` is true ([#XXXX](https://github.com/getsentry/sentry-ruby/pull/XXXX))
+
+  Rails structured logging is now automatically enabled when `config.enable_logs = true` is set, eliminating the need for the double opt-in. Users can still explicitly disable it by setting `config.rails.structured_logging.enabled = false` before setting `enable_logs = true`.
+
+  **Before:**
+  ```ruby
+  Sentry.init do |config|
+    config.enable_logs = true
+    config.rails.structured_logging.enabled = true  # Required
+  end
+  ```
+
+  **After:**
+  ```ruby
+  Sentry.init do |config|
+    config.enable_logs = true
+    # Rails structured logging is now automatically enabled!
+  end
+  ```
+
+  **To explicitly disable:**
+  ```ruby
+  Sentry.init do |config|
+    config.rails.structured_logging.enabled = false  # Explicit disable
+    config.enable_logs = true  # Won't auto-enable structured logging
+  end
+  ```
 
 ### Bug Fixes
 
@@ -26,26 +53,20 @@
   Sentry.init do |config|
     # ... your setup ...
 
-    # Make sure structured logging is enabled
+    # Enable structured logging (Rails log subscribers are auto-enabled)
     config.enable_logs = true
-
-    # Enable default Rails log subscribers (ActionController and ActiveRecord)
-    config.rails.structured_logging.enabled = true
   end
   ```
 
-  To configure all subscribers:
+  To configure additional subscribers:
 
   ```ruby
   Sentry.init do |config|
     # ... your setup ...
 
-    # Make sure structured logging is enabled
+    # Enable structured logging (Rails log subscribers are auto-enabled)
     config.enable_logs = true
 
-    # Enable Rails log subscribers
-    config.rails.structured_logging.enabled = true
-
     # Add ActionMailer and ActiveJob subscribers
     config.rails.structured_logging.subscribers.update(
       action_mailer: Sentry::Rails::LogSubscribers::ActionMailerSubscriber,

sentry-rails/lib/sentry/rails/configuration.rb

@@ -14,7 +14,7 @@ class Configuration
     attr_reader :rails
 
     add_post_initialization_callback do
-      @rails = Sentry::Rails::Configuration.new
+      @rails = Sentry::Rails::Configuration.new(self)
       @excluded_exceptions = @excluded_exceptions.concat(Sentry::Rails::IGNORE_DEFAULT)
 
       if ::Rails.logger
@@ -166,7 +166,7 @@ class Configuration
       # @return [StructuredLoggingConfiguration]
       attr_reader :structured_logging
 
-      def initialize
+      def initialize(parent_config = nil)
         @register_error_subscriber = false
         @report_rescued_exceptions = true
         @skippable_job_adapters = []
@@ -183,7 +183,7 @@ def initialize
         @db_query_source_threshold_ms = 100
         @active_support_logger_subscription_items = Sentry::Rails::ACTIVE_SUPPORT_LOGGER_SUBSCRIPTION_ITEMS_DEFAULT.dup
         @active_job_report_on_retry_error = false
-        @structured_logging = StructuredLoggingConfiguration.new
+        @structured_logging = StructuredLoggingConfiguration.new(parent_config)
       end
     end
 
@@ -192,18 +192,30 @@ class StructuredLoggingConfiguration
       # @return [Boolean]
       attr_accessor :enabled
 
+      private :enabled
+
       # Hash of components to subscriber classes for structured logging
       # @return [Hash<Symbol, Class>]
       attr_accessor :subscribers
 
+      # @return [Sentry::Configuration]
+      attr_reader :parent_config
+
       DEFAULT_SUBSCRIBERS = {
         active_record: Sentry::Rails::LogSubscribers::ActiveRecordSubscriber,
         action_controller: Sentry::Rails::LogSubscribers::ActionControllerSubscriber
       }.freeze
 
-      def initialize
-        @enabled = false
+      def initialize(parent_config)
+        @enabled = nil
         @subscribers = DEFAULT_SUBSCRIBERS.dup
+        @parent_config = parent_config
+      end
+
+      # Returns true if structured logging should be enabled.
+      # @return [Boolean]
+      def enabled?
+        enabled.nil? ? parent_config.enable_logs : enabled
       end
     end
   end

sentry-rails/lib/sentry/rails/railtie.rb

@@ -140,7 +140,7 @@ def activate_tracing
     end
 
     def activate_structured_logging
-      if Sentry.configuration.rails.structured_logging.enabled && Sentry.configuration.enable_logs
+      if Sentry.configuration.rails.structured_logging.enabled? && Sentry.configuration.enable_logs
         Sentry::Rails::StructuredLogging.attach(Sentry.configuration.rails.structured_logging)
       end
     end

sentry-rails/spec/sentry/rails/configuration_spec.rb

@@ -74,7 +74,7 @@ class MySubscriber; end
         config.rails.structured_logging.enabled = true
       end
 
-      expect(config.structured_logging.enabled).to be(true)
+      expect(config.structured_logging.enabled?).to be(true)
       expect(config.structured_logging.subscribers).to be_a(Hash)
     end
 
@@ -83,10 +83,35 @@ class MySubscriber; end
         config.rails.structured_logging.enabled = false
       end
 
-      expect(config.structured_logging.enabled).to be(false)
+      expect(config.structured_logging.enabled?).to be(false)
       expect(config.structured_logging.subscribers).to be_a(Hash)
     end
 
+    it "auto-enables when enable_logs is true and not explicitly set" do
+      make_basic_app do |config|
+        config.enable_logs = true
+      end
+
+      expect(config.structured_logging.enabled?).to be(true)
+    end
+
+    it "remains disabled when enable_logs is false" do
+      make_basic_app do |config|
+        config.enable_logs = false
+      end
+
+      expect(config.structured_logging.enabled?).to be(false)
+    end
+
+    it "respects explicit disable even when enable_logs is true" do
+      make_basic_app do |config|
+        config.rails.structured_logging.enabled = false
+        config.enable_logs = true
+      end
+
+      expect(config.structured_logging.enabled?).to be(false)
+    end
+
     it "allows customizing subscribers" do
       class TestSubscriber; end
 

sentry-rails/spec/sentry/rails/log_subscriber_spec.rb

@@ -45,6 +45,8 @@ def error_test_event(event)
       make_basic_app do |config|
         config.enable_logs = true
         config.structured_logging.logger_class = Sentry::DebugStructuredLogger
+        # Disable default structured logging subscribers to avoid interference
+        config.rails.structured_logging.enabled = false
       end
     end
 
@@ -123,8 +125,8 @@ def error_test_event(event)
         duration = log_event["attributes"]["duration_ms"]
 
         expect(duration).to be_a(Float)
-        expect(duration).to be >= 40.0
-        expect(duration).to be < 100.0
+        expect(duration).to be >= 10.0  # At least 10ms (reduced from 40ms)
+        expect(duration).to be < 200.0  # Less than 200ms (increased from 100ms)
         expect(duration.round(2)).to eq(duration)
       end
     end

sentry-rails/spec/sentry/rails/structured_logging_spec.rb

@@ -40,4 +40,27 @@
       expect(sentry_logs).to be_empty
     end
   end
+
+  context "when enable_logs is true and structured logging is auto-enabled" do
+    before do
+      make_basic_app do |config|
+        config.enable_logs = true
+        # Don't explicitly set rails.structured_logging.enabled - should auto-enable
+      end
+    end
+
+    it "captures structured logs automatically" do
+      get "/posts"
+
+      Post.first
+
+      Sentry.get_current_client.flush
+
+      expect(sentry_logs).not_to be_empty
+
+      # Should have logs from both ActionController and ActiveRecord subscribers
+      controller_logs = sentry_logs.select { |log| log.dig(:attributes, "sentry.origin", :value) == "auto.logger.rails.log_subscriber" }
+      expect(controller_logs).not_to be_empty
+    end
+  end
 end