Deploy rails app with capistrano rbenv unicorn

Question

I have problem staring unicorn during deploy. The stack trace is the same as if I execute from "app_name"/current directory:

bundle exec rails c production

deployer@cloud-number-nine:~/qna/current$ bundle exec rails c production
[DEPRECATION] the dotenv-deployment gem is deprecated. See https://github.com/bkeepers/dotenv-deployment#readme.
/home/deployer/qna/releases/20160521190207/app/serializers/votable_serializer.rb:5:in `<class:VotableSerializer>': undefined method `root=' for VotableSerializer:Class (NoMethodError)
    from /home/deployer/qna/releases/20160521190207/app/serializers/votable_serializer.rb:2:in `<top (required)>'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `block in require'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:360:in `require_or_load'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:317:in `depend_on'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:233:in `require_dependency'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/engine.rb:472:in `block (2 levels) in eager_load!'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/engine.rb:471:in `each'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/engine.rb:471:in `block in eager_load!'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/engine.rb:469:in `each'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/engine.rb:469:in `eager_load!'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/engine.rb:346:in `eager_load!'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/application/finisher.rb:56:in `each'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/application/finisher.rb:56:in `block in <module:Finisher>'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:30:in `instance_exec'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:30:in `run'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:55:in `block in run_initializers'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:228:in `block in tsort_each'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:431:in `each_strongly_connected_component_from'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:349:in `block in each_strongly_connected_component'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `call'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:347:in `each_strongly_connected_component'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:226:in `tsort_each'
    from /home/deployer/.rbenv/versions/2.3.0/lib/ruby/2.3.0/tsort.rb:205:in `tsort_each'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/initializable.rb:54:in `run_initializers'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/application.rb:352:in `initialize!'
    from /home/deployer/qna/releases/20160521190207/config/environment.rb:5:in `<top (required)>'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `block in require'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:240:in `load_dependency'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/activesupport-4.2.5/lib/active_support/dependencies.rb:274:in `require'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/application.rb:328:in `require_environment!'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:142:in `require_application_and_environment!'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:67:in `console'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/commands/commands_tasks.rb:39:in `run_command!'
    from /home/deployer/qna/shared/bundle/ruby/2.3.0/gems/railties-4.2.5/lib/rails/commands.rb:17:in `<top (required)>'
    from bin/rails:9:in `require'
    from bin/rails:9:in `<main>'

Capfile:

# Load DSL and set up stages
require 'capistrano/setup'

# Include default deployment tasks
require 'capistrano/deploy'
require 'capistrano/rbenv'
require 'capistrano/bundler'
require 'capistrano/rails'
require 'capistrano/sidekiq'
require 'capistrano3/unicorn'
require 'whenever/capistrano'
require 'thinking_sphinx/capistrano'

Dir.glob('lib/capistrano/tasks/*.rake').each { |r| import r }

deploy.rb

# config valid only for current version of Capistrano
lock '3.5.0'

set :application, 'qna'
set :repo_url, 'git@github.com:khataev/qna.git'

# Default deploy_to directory is /var/www/my_app_name
set :deploy_to, '/home/deployer/qna'
set :deploy_user, 'deployer'

# Default value for :linked_files is []
set :linked_files, fetch(:linked_files, []).push('config/database.yml', 'config/private_pub.yml', 'config/private_pub_thin.yml', '.env')

# Default value for linked_dirs is []
set :linked_dirs, fetch(:linked_dirs, []).push('log', 'tmp/pids', 'tmp/cache', 'tmp/sockets', 'public/system', 'vendor/bundle', 'public/uploads')

# rbenv
set :rbenv_type, :user # or :system, depends on your rbenv setup
set :rbenv_ruby, '2.3.0'

set :rbenv_prefix, "RBENV_ROOT=#{fetch(:rbenv_path)} RBENV_VERSION=#{fetch(:rbenv_ruby)} #{fetch(:rbenv_path)}/bin/rbenv exec"
# set :rbenv_map_bins, %w(rake gem bundle ruby rails)
set :rbenv_roles, :all # default value
set :bundle_binstubs, nil

namespace :deploy do
  desc 'Restart application'
  task :restart do
    on roles(:app), in: :sequence, wait: 5 do
      # execute :touch, release_path.join('tmp/restart.txt')
      invoke 'unicorn:restart'
    end
  end

  after :publishing, :restart
end

namespace :private_pub do
  desc 'Start private_pub server'
  task :start do
    on roles(:app) do
      within current_path do
        with rails_env: fetch(:rails_env) do
          execute :bundle, 'exec thin -C config/private_pub_thin.yml start'
        end
      end
    end
  end

  desc 'Stop private_pub server'
  task :stop do
    on roles(:app) do
      within current_path do
        with rails_env: fetch(:rails_env) do
          execute :bundle, 'exec thin -C config/private_pub_thin.yml stop'
        end
      end
    end
  end

  desc 'Restart private_pub server'
  task :restart do
    on roles(:app) do
      within current_path do
        with rails_env: fetch(:rails_env) do
          execute :bundle, 'exec thin -C config/private_pub_thin.yml restart'
        end
      end
    end
  end
end

after 'deploy:restart', 'private_pub:restart'
after 'deploy:restart', 'thinking_sphinx:restart'

unicorn/production.rb

# paths
app_path = '/home/deployer/qna'
working_directory "#{app_path}/current"
pid               "#{app_path}/current/tmp/pids/unicorn.pid"

# listen
listen '/tmp/unicorn.qna.sock', backlog: 64

# logging
stderr_path 'log/unicorn.stderr.log'
stdout_path 'log/unicorn.stdout.log'

# workers
worker_processes 2

# use correct Gemfile on restarts
before_exec do |_server|
  ENV['BUNDLE_GEMFILE'] = "#{app_path}/current/Gemfile"
end

# preload
preload_app true

before_fork do |server, _worker|
  # the following is highly recomended for Rails + "preload_app true"
  # as there's no need for the master process to hold a connection
  ActiveRecord::Base.connection.disconnect! if defined?(ActiveRecord::Base)

  # Before forking, kill the master process that belongs to the .oldbin PID.
  # This enables 0 downtime deploys.
  old_pid = "#{server.config[:pid]}.oldbin"
  if File.exist?(old_pid) && server.pid != old_pid
    begin
      Process.kill('QUIT', File.read(old_pid).to_i)
    rescue Errno::ENOENT, Errno::ESRCH
      # someone else did our job for us
    end
  end
end

after_fork do |_server, _worker|
  ActiveRecord::Base.establish_connection if defined?(ActiveRecord::Base)
end

votable serializer

My opinion that problem lies between rbenv and unicorn, but I'm not shure...

Answer 1

I believe that your problem is actually not related to unicorn . In a comment above you said that "it didn't cause problems in production until I wanted to migrate from passenger to unicorn" . But, the commit to switch to unicorn reveals that during this step the active_model_serializers gem has been upgraded from version 0.9.5 to 0.10.0.

This turns out to be significant for your serializer as it seems that the self.root= method can no longer be used in the class context - it is now a normal attr_accessor in the ActiveModel::Serializer class, ie if at all, then it should be used in the instance context. See the old version vs the new version .

Anyway, if you wanted to just NOT include the root when serializing the object, you should just be able to switch to the - now default - AttributesAdapter . You may use the adapter: :attributes when rendering the objects in your controller.