I add Gem \'unicorn\' to Gemfile and call rails server unicorn -e production, but I get a load error. Then I add Gem \'unicorn_rails\'
Gem \'unicorn\'
rails server unicorn -e production
Gem \'unicorn_rails\'
web: bundle exec unicorn -p $PORT -c ./config/unicorn.rb service unicorn_projectName start
works for me