Capistrano 3. Wrong path in the shared_path variable

Question

I'am trying to create the Unicorn restart task with Capistrano 3:

Firstly, I set *unicorn_pid* variable:

set :unicorn_pid, "#{shared_path}/tmp/pids/unicorn.pid"

Then I pass it to the restart task:

  desc 'Restart application'
  task :restart do
    on roles(:app), in: :sequence, wait: 5 do
      execute :kill, "-USR2 `cat #{fetch(:unicorn_pid)}`" if test "[ -f #{fetch(:unicorn_pid)} ]"
      within release_path do
        execute :bundle, "exec unicorn -D -c config/unicorn.rb -E #{fetch(:stage)}"
      end
    end
  end

but when i run cap production deploy:restart i see:

DEBUG [f4159760] Running /usr/bin/env [ -f /var/www/shared/tmp/pids/unicorn.pid ] on dev.project.net
DEBUG [f4159760] Command: [ -f /var/www/shared/tmp/pids/unicorn.pid ]

So, instead /home/user/project/shared/ path, #{shared_path} transform to /var/www/shared/

But when I specify this path directly in the task, without unicorn_pid variable I see in the output:

 INFO [567856e3] Running /usr/bin/env kill -USR2 `cat /home/user/project/shared/tmp/pids/unicorn.pid` on dev.educapsule.net
DEBUG [567856e3] Command: /usr/bin/env kill -USR2 `cat /home/user/project/shared/tmp/pids/unicorn.pid`

Why the path is changed to /var/www/shared/ when I pass it in "custom" variable?

Thanks.

Answer 1

I think the problem is that when you call this:

set :unicorn_pid, "#{shared_path}/tmp/pids/unicorn.pid"

It's being evaluated the moment that line is processed, taking the as-then-current value of shared_path which is /var/www/shared.

Try changing that line to this which should delay it's execution until you actually reference unicorn_pid.

set :unicorn_pid, -> {"#{shared_path}/tmp/pids/unicorn.pid"}