Nginx – Multiple Unicorns/Rails Apps, Nginx, One User

nginxunicorn

  1. I successfully deployed a Rails app using Capistrano, Unicorn, Nginx using the following unicorn configuration:

    env = ENV["RAILS_ENV"] || "development"

worker_processes 4

listen "/tmp/app_one.socket", :backlog => 64

preload_app true

timeout 60

pid "/tmp/unicorn.app_one.pid"

if env == "production"
  working_directory "/home/single_user/app_one/current"

  user 'single_user'

  shared_path = "/home/single_user/app_one/shared"

  stderr_path "#{shared_path}/log/unicorn.stderr.log"
  stdout_path "#{shared_path}/log/unicorn.stdout.log"
end

before_fork do |server, worker|
  if defined?(ActiveRecord::Base)
    ActiveRecord::Base.connection.disconnect!
  end

  old_pid = "/tmp/unicorn.app_one.pid.oldbin"
  if File.exists?(old_pid) && server.pid != old_pid
    begin
      Process.kill("QUIT", File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      # already dead
    end
  end
end

after_fork do |server, worker|
  if defined?(ActiveRecord::Base)
    ActiveRecord::Base.establish_connection
  end
end

  2. Under the same single_user, I added a second Rails app, a second Nginx virtual server, and used the exact same Unicorn config, replacing app_one with app_two in all the appropriate places.

  3. My second app deployed just fine, but now I am having trouble deploying app one. The /tmp/unicorn.app_one.pid does not exist, but the site still works fine (top showing ten processes as expected). However /tmp/app_one.socket does exist, which prevents me from starting Unicorn by hand.

So is this the appropriate practice, to run multiple Rails/Unicorn/Nginx under the same user? Have I caused some kind of conflict in my deployment process? How should I proceed without breaking app_one, which is live and in use?

Best Answer

Why don't you use an app-specific tmp directory, and put the unicorn.pid into there, like "#{working_directory}/tmp/unicorn.pid". Similarly for any app-specific files like the socket. If you don't want to put it in working_directory, use shared_path. Keep everything specific to app1 in an app1-specific location, and everything related to app2 in an app2-specific directory.

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