How do I reload Unicorn without killing the master process?

Question

I have a RubyOnRails project, and deployed it with Unicorn on nginx on an Ubuntu server.

I need to restart Unicorn if I change one of configuration files, but it makes my site shut down when I kill Unicorn's master process and start it again with bundle exec.

Is there any way to make Unicorn work with new files without killing the process and going down?

Answer 1

In my capistrano deploy.rb I have:

desc "Zero-downtime restart of Unicorn"
task :restart, :except => { :no_release => true } do
  run "kill -s USR2 unicorn_pid"
end

This is well documented in "Lighting fast, zero-downtime deployments with git, capistrano, nginx and Unicorn".

Answer 2

Both answers, including the accepted one, are bad.

http://unicorn.bogomips.org/SIGNALS.html says send a HUP to the master process.

desc "Zero-downtime restart of Unicorn"
task :restart, :except => { :no_release => true } do
  run "kill -s HUP `cat tmp/pids/unicorn.pid`"
end