Make the log level in DebugExceptions configurable

actionpack/lib/action_dispatch/middleware/debug_exceptions.rb

@@ -145,16 +145,18 @@ def log_error(request, wrapper)
         message << "  "
         message.concat(trace)
 
-        log_array(logger, message)
+        log_array(logger, message, request)
       end
 
-      def log_array(logger, lines)
+      def log_array(logger, lines, request)
         return if lines.empty?
 
+        level = request.get_header("action_dispatch.debug_exception_log_level")
+
         if logger.formatter && logger.formatter.respond_to?(:tags_text)
-          logger.fatal lines.join("\n#{logger.formatter.tags_text}")
+          logger.add(level, lines.join("\n#{logger.formatter.tags_text}"))
         else
-          logger.fatal lines.join("\n")
+          logger.add(level, lines.join("\n"))
         end
       end
 

actionpack/lib/action_dispatch/railtie.rb

@@ -26,6 +26,7 @@ class Railtie < Rails::Railtie # :nodoc:
     config.action_dispatch.perform_deep_munge = true
     config.action_dispatch.request_id_header = "X-Request-Id"
     config.action_dispatch.log_rescued_responses = true
+    config.action_dispatch.debug_exception_log_level = :fatal
 
     config.action_dispatch.default_headers = {
       "X-Frame-Options" => "SAMEORIGIN",

actionpack/test/dispatch/debug_exceptions_test.rb

@@ -456,6 +456,19 @@ def call(env)
     assert_match(/puke/, output.rewind && output.read)
   end
 
+  test "logs at configured log level" do
+    @app = DevelopmentApp
+    output = StringIO.new
+    logger = Logger.new(output)
+    logger.level = Logger::WARN
+
+    get "/", headers: { "action_dispatch.show_exceptions" => :all, "action_dispatch.logger" => logger, "action_dispatch.debug_exception_log_level" => Logger::INFO }
+    assert_no_match(/puke/, output.rewind && output.read)
+
+    get "/", headers: { "action_dispatch.show_exceptions" => :all, "action_dispatch.logger" => logger, "action_dispatch.debug_exception_log_level" => Logger::ERROR }
+    assert_match(/puke/, output.rewind && output.read)
+  end
+
   test "logs only what is necessary" do
     @app = DevelopmentApp
     io = StringIO.new

guides/source/configuring.md

@@ -61,6 +61,7 @@ Below are the default values associated with each target version. In cases of co
 #### Default Values for Target Version 7.1
 
 - [`config.action_controller.allow_deprecated_parameters_hash_equality`](#config-action-controller-allow-deprecated-parameters-hash-equality): `false`
+- [`config.action_dispatch.debug_exception_log_level`](#config-action-dispatch-debug-exception-log-level): `:error`
 - [`config.action_dispatch.default_headers`](#config-action-dispatch-default-headers): `{ "X-Frame-Options" => "SAMEORIGIN", "X-XSS-Protection" => "0", "X-Content-Type-Options" => "nosniff", "X-Permitted-Cross-Domain-Policies" => "none", "Referrer-Policy" => "strict-origin-when-cross-origin" }`
 - [`config.action_view.sanitizer_vendor`](#config-action-view-sanitizer-vendor): `Rails::HTML::Sanitizer.best_supported_vendor`
 - [`config.active_job.use_big_decimal_serializer`](#config-active-job-use-big-decimal-serializer): `true`
@@ -1689,6 +1690,18 @@ The default value depends on the `config.load_defaults` target version:
 | (original)            | `:marshal`           |
 | 7.0                   | `:json`              |
 
+#### `config.action_dispatch.debug_exception_log_level`
+
+Configure the log level used by the DebugExceptions middleware when logging
+uncaught exceptions during requests
+
+The default value depends on the `config.load_defaults` target version:
+
+| Starting with version | The default value is |
+| --------------------- | -------------------- |
+| (original)            | `:fatal`             |
+| 7.1                   | `:error`             |
+
 #### `config.action_dispatch.default_headers`
 
 Is a hash with HTTP headers that are set by default in each response.

railties/CHANGELOG.md

@@ -1,3 +1,11 @@
+*   Add `config.action_dispatch.debug_exception_log_level` to configure the log
+    level used by `ActionDispatch::DebugExceptions`.
+
+    The default is `:fatal`, but with `load_defaults "7.1"` the default will be
+    `:error`.
+
+    *Hartley McGuire*
+
 *   Add `DATABASE` option to `railties:install:migrations`
 
     This allows you to specify which database the migrations should be copied to

railties/lib/rails/application.rb

@@ -303,6 +303,7 @@ def env_config
           "action_dispatch.show_exceptions" => config.action_dispatch.show_exceptions,
           "action_dispatch.show_detailed_exceptions" => config.consider_all_requests_local,
           "action_dispatch.log_rescued_responses" => config.action_dispatch.log_rescued_responses,
+          "action_dispatch.debug_exception_log_level" => ActiveSupport::Logger.const_get(config.action_dispatch.debug_exception_log_level.to_s.upcase),
           "action_dispatch.logger" => Rails.logger,
           "action_dispatch.backtrace_cleaner" => Rails.backtrace_cleaner,
           "action_dispatch.key_generator" => key_generator,

railties/lib/rails/application/configuration.rb

@@ -297,6 +297,7 @@ def load_defaults(target_version)
               "X-Permitted-Cross-Domain-Policies" => "none",
               "Referrer-Policy" => "strict-origin-when-cross-origin"
             }
+            action_dispatch.debug_exception_log_level = :error
           end
 
           if respond_to?(:active_job)

railties/lib/rails/generators/rails/app/templates/config/initializers/new_framework_defaults_7_1.rb.tt

@@ -190,3 +190,7 @@
 # In previous versions of Rails, Action View always used `Rails::HTML4::Sanitizer`.
 #
 # Rails.application.config.action_view.sanitizer_vendor = Rails::HTML::Sanitizer.best_supported_vendor
+
+# Configure the log level used by the DebugExceptions middleware when logging
+# uncaught exceptions during requests
+# Rails.application.config.action_dispatch.debug_exception_log_level = :error

railties/test/application/configuration_test.rb

@@ -2622,6 +2622,36 @@ def index
       assert_equal :default, Rails.configuration.debug_exception_response_format
     end
 
+    test "debug_exception_log_level is :fatal by default for upgraded apps" do
+      make_basic_app
+
+      class ::OmgController < ActionController::Base
+        def index
+          render plain: request.env["action_dispatch.debug_exception_log_level"]
+        end
+      end
+
+      get "/"
+
+      assert_equal "4", last_response.body
+    end
+
+    test "debug_exception_log_level is :error for new apps" do
+      make_basic_app do |app|
+        app.config.load_defaults "7.1"
+      end
+
+      class ::OmgController < ActionController::Base
+        def index
+          render plain: request.env["action_dispatch.debug_exception_log_level"]
+        end
+      end
+
+      get "/"
+
+      assert_equal "3", last_response.body
+    end
+
     test "ActiveRecord::Base.has_many_inversing is true by default for new apps" do
       app "development"