Reduce log noise handling ActionController::RoutingErrors

Each time a missing route is hit 32 lines of internal rails traces
are written to the log. This is overly verbose and doesn't offer
any actionable information to the user.

With this change we'll still write an error message showing the
route error but the trace will be omitted.

4 files changed, 34 insertions, 3 deletions

diff --git a/actionpack/CHANGELOG.md b/actionpack/CHANGELOG.md
index 4bcf313ecc..9a631f8f86 100644
--- a/actionpack/CHANGELOG.md
+++ b/actionpack/CHANGELOG.md
@@ -1,3 +1,7 @@
+*   Reduced log noise handling ActionController::RoutingErrors.
+
+    *Alberto Fernández-Capel*
+
 *   Keep part when scope option has value
 
     When a route was defined within an optional scope, if that route didn't
diff --git a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
index 59113e13f4..6435947434 100644
--- a/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
+++ b/actionpack/lib/action_dispatch/middleware/debug_exceptions.rb
@@ -138,9 +138,7 @@ module ActionDispatch
         return unless logger
 
         exception = wrapper.exception
-
-        trace = wrapper.application_trace
-        trace = wrapper.framework_trace if trace.empty?
+        trace = wrapper.exception_trace
 
         ActiveSupport::Deprecation.silence do
           message = []
diff --git a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
index 0cc56f5013..2bf3ddb540 100644
--- a/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
+++ b/actionpack/lib/action_dispatch/middleware/exception_wrapper.rb
@@ -62,6 +62,12 @@ module ActionDispatch
       self.class.status_code_for_exception(unwrapped_exception.class.name)
     end
 
+    def exception_trace
+      trace = application_trace
+      trace = framework_trace if trace.empty? && !exception.is_a?(ActionController::RoutingError)
+      trace
+    end
+
     def application_trace
       clean_backtrace(:silent)
     end
diff --git a/actionpack/test/dispatch/debug_exceptions_test.rb b/actionpack/test/dispatch/debug_exceptions_test.rb
index 3e57e8f4d9..7adf935849 100644
--- a/actionpack/test/dispatch/debug_exceptions_test.rb
+++ b/actionpack/test/dispatch/debug_exceptions_test.rb
@@ -466,6 +466,8 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
   end
 
   test "logs exception backtrace when all lines silenced" do
+    @app = DevelopmentApp
+
     output = StringIO.new
     backtrace_cleaner = ActiveSupport::BacktraceCleaner.new
     backtrace_cleaner.add_silencer { true }
@@ -478,6 +480,27 @@ class DebugExceptionsTest < ActionDispatch::IntegrationTest
     assert_operator((output.rewind && output.read).lines.count, :>, 10)
   end
 
+  test "doesn't log the framework backtrace when error type is a routing error" do
+    @app = ProductionApp
+
+    output = StringIO.new
+    backtrace_cleaner = ActiveSupport::BacktraceCleaner.new
+    backtrace_cleaner.add_silencer { true }
+
+    env = { "action_dispatch.show_exceptions"   => true,
+            "action_dispatch.logger"            => Logger.new(output),
+            "action_dispatch.backtrace_cleaner" => backtrace_cleaner }
+
+    assert_raises ActionController::RoutingError do
+      get "/pass", headers: env
+    end
+
+    log = output.rewind && output.read
+
+    assert_includes log, "ActionController::RoutingError (No route matches [GET] \"/pass\")"
+    assert_equal 3, log.lines.count
+  end
+
   test "display backtrace when error type is SyntaxError" do
     @app = DevelopmentApp