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MaintenanceServer ================= It is assumed that your web application is a mongrel cluster running behind Pound, Pen, or another load balancing program that can be configured to use an 'emergency' back-end for when all regular back-ends fail. This plugin provides a lightweight 'maintenance' server to act as that emergency back-end for when your Rails app is down for maintenance, or due to a fatal error. After installation, a new script/maintenance_server command is available, which runs a small (Mongrel) web server instance listening on the specified port. The web server will serve files under RAILS_ROOT/public as usual, while unconditionally returning a "503 Unavailable" server response for any other request, and rendering a nice apologetic HTML page at RAILS_ROOT/public/maintenance.html (provided). The plugin's home on the web is here: http://git.sanityinc.com/?p=maintenance_server.git;a=summary The plugin is discussed in blog articles here: http://www.sanityinc.com/ Send feedback or patches by email to firstname.lastname@example.org Example ======= Install the plugin as usual. If you do not install it with either script/plugin or rapt, then be sure to run the install.rb script manually. The installation will create a new 'script/maintenance_server' script, and a reasonable default 'unavailable' page at 'public/maintenance.html'. Start the maintenance_server on the port of your choice, as follows: ./script/maintenance_server PORT (You may want to use software such as daemontools or runit to ensure that the server is automatically started with your system and restarted if it fails or is killed.) Given mongrel_rails back-ends on ports 8000, 8001 etc., and maintenance_server running on port 8020, sample configuration for Pound might look something like this: ListenHTTP Address 0.0.0.0 Port 80 Service BackEnd Address 127.0.0.1 Port 8000 End BackEnd Address 127.0.0.1 Port 8001 End ... # other back-ends here Emergency Address 127.0.0.1 Port 8020 End End End In the same scenario, one might start the excellent Pen load-balancer with the following command-line: pen -f -r -b 5 -e localhost:8020 \ localhost:80 \ localhost:8000 localhost:8001 localhost:8002 \ ... Copyright (c) 2007 Steve Purcell, released under the MIT license