Added AppError middleware

config.ru

@@ -28,6 +28,9 @@ end
 # show exceptions when not-production
 unless 'production' == ENV['RACK_ENV']
   use Rack::ShowExceptions
+else
+  require './lib/rack/app_error'
+  use Rack::AppError, :file => 'public/500.html'
 end
 
 

lib/rack/app_error.rb

@@ -0,0 +1,64 @@
+# blog.ixti.ru, private scratchpad with public access
+# 
+# Copyright (c) 2011 Aleksey V Zapparov AKA ixti <ixti@member.fsf.org>
+# 
+# blog.ixti.ru is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# blog.ixti.ru is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with blog.ixti.ru.  If not, see <http://www.gnu.org/licenses/>.
+
+
+module Rack
+  class AppError
+    def initialize(app, options={})
+      @app = app
+      @file = options[:file]
+    end
+
+    def call(env)
+      @app.call(env)
+    rescue StandardError, LoadError, SyntaxError => e
+      env["rack.errors"].puts(dump_exception e)
+      env["rack.errors"].flush
+
+      if prefers_plain_text?(env)
+        content_type = "text/plain"
+        body = "Application Error\n"
+      else
+        content_type = "text/html"
+        body = ::IO.readlines @file
+      end
+
+      [
+        500,
+        {
+          "Content-Type" => content_type,
+          "Content-Length" => Rack::Utils.bytesize(body.join).to_s
+        },
+        body
+      ]
+    end
+
+    protected
+
+    def prefers_plain_text?(env)
+      env["HTTP_X_REQUESTED_WITH"] == "XMLHttpRequest" && (!env["HTTP_ACCEPT"] || !env["HTTP_ACCEPT"].include?("text/html"))
+    end
+
+    def dump_exception(exception)
+      string = "#{exception.class}: #{exception.message}\n"
+      string << exception.backtrace.map { |l| "\t#{l}" }.join("\n")
+      string
+    end
+  end
+end
+
+# vim:ts=2:sw=2