Question

Ok, so I would like to create an action in Rails to restart itself. I did a little searching and found:

http://snippets.dzone.com/posts/show/5002

Which suggests 2 commands, one to stop and another to restart. The following kills:

ps -a|grep '/usr/local/bin/ruby script/server'|grep -v 'grep /usr'|cut -d ' ' -f1|xargs -n 1 kill -KILL $1 

The -HUP signal doesn’t restart for me, so I tried to mangle the above command (adjusted so the command worked fine with how I was starting the server under Ubuntu):

ps -eaf|grep 'ruby script/server'|grep -v grep|cut -d ' ' -f3|xargs -n 1 kill -KILL $1;script/server 

This works fine in my environment, so I tried to set up an action to execute it:

def restart   fork { exec 'ps -eaf|grep \'ruby script/server\'|grep -v grep|cut -d \' \' -f3|xargs -n 1 kill -KILL $1;script/server' }   redirect_to '/server_maintenance' end 

The action kills the server fine, but doesn’t actually start the server back up:

=> Booting Mongrel => Rails 2.3.2 application starting on http://0.0.0.0:3000 => Call with -d to detach => Ctrl-C to shutdown server Exiting /usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/tcphack.rb:12:in `initialize_without_backlog': Address already in use - bind(2) (Errno::EADDRINUSE)     from /usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel/tcphack.rb:12:in `initialize'     from /usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:93:in `new'     from /usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:93:in `initialize'     from /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/handler/mongrel.rb:10:in `new'     from /usr/lib/ruby/gems/1.8/gems/actionpack-2.3.2/lib/action_controller/vendor/rack-1.0/rack/handler/mongrel.rb:10:in `run'     from /usr/lib/ruby/gems/1.8/gems/rails-2.3.2/lib/commands/server.rb:111     from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require'     from /usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `require'     from script/server:3 

I’m not quite understanding why the address is already in use when Mongrel seems to have just exited.

I found this question:

How do you restart Rails under Mongrel, without stopping and starting Mongrel

but the signals don’t cause the restart in my environment, they just end up killing the process.

Anyone have any ideas on what may work? For some notes on my environment: I installed Rails from a new version of RubyGems, and Mongrel. I use script/server to start the server, which of course uses Mongrel. I’m on Ubuntu Hardy Heron.

Answer 1

Ok I found a fix… I changed how I start rails to:

mongrel_rails start -d 

and now the following action will do it:

def restart   fork { exec 'mongrel_rails restart' }   redirect_to '/server_maintenance' end 

As a caveat, the redirect_to will cause a failed load because the server will be down… however a reload after a pause will show that the restart was successful. This could be fixed by changing the restart to be done with AJAX, followed by a javascript reload… but I will leave that as an exercise to the reader.