Starting or restarting Unicorn with Capistrano 3.x

Question

I'm trying to start or restart Unicorn when I do cap production deploy with Capistrano 3.0.1. I have some examples that I got working with Capistrano 2.x using something like:

namespace :unicorn do
  desc "Start unicorn for this application"
  task :start do
    run "cd #{current_path} && bundle exec unicorn -c /etc/unicorn/myapp.conf.rb -D"
  end
end

But when I try and use run in the deploy.rb for Capistrano 3.x I get an undefined method error.

Here are a couple of the things I tried:

# within the :deploy I created a task that I called after :finished
namespace :deploy do
...

  task :unicorn do
    run "cd #{current_path} && bundle exec unicorn -c /etc/unicorn/myapp.conf.rb -D"
  end

  after :finished, 'deploy:unicorn'

end

I have also tried putting the run within the :restart task

namespace :deploy do
  desc 'Restart application'
  task :restart do

  on roles(:app), in: :sequence, wait: 5 do
    # Your restart mechanism here, for example:
    # execute :touch, release_path.join('tmp/restart.txt')
    execute :run, "cd #{current_path} && bundle exec unicorn -c /etc/unicorn/deployrails.conf.rb -D"
  end
end    

If I use just run "cd ... " then I'll get awrong number of arguments (1 for 0)` in the local shell.

I can start the unicorn process with unicorn -c /etc/unicorn/deployrails.conf.rb -D from my ssh'd VM shell.

I can kill the master Unicorn process from the VM shell using kill USR2, but even though the process is killed I get an error. I can then start the process again using unicorn -c ...

$ kill USR2 58798
bash: kill: USR2: arguments must be process or job IDs

I'm very new to Ruby, Rails and Deployment in general. I have a VirtualBox setup with Ubuntu, Nginx, RVM and Unicorn, I'm pretty excited so far, but this one is really messing with me, any advice or insight is appreciated.

Answer 1

I'm using following code:

namespace :unicorn do
  desc 'Stop Unicorn'
  task :stop do
    on roles(:app) do
      if test("[ -f #{fetch(:unicorn_pid)} ]")
        execute :kill, capture(:cat, fetch(:unicorn_pid))
      end
    end
  end

  desc 'Start Unicorn'
  task :start do
    on roles(:app) do
      within current_path do
        with rails_env: fetch(:rails_env) do
          execute :bundle, "exec unicorn -c #{fetch(:unicorn_config)} -D"
        end
      end
    end
  end

  desc 'Reload Unicorn without killing master process'
  task :reload do
    on roles(:app) do
      if test("[ -f #{fetch(:unicorn_pid)} ]")
        execute :kill, '-s USR2', capture(:cat, fetch(:unicorn_pid))
      else
        error 'Unicorn process not running'
      end
    end
  end

  desc 'Restart Unicorn'
  task :restart
  before :restart, :stop
  before :restart, :start
end