AWSにrails アプリをデプロイしていて、アプリ起動でハマっています。
rails を起動時にunicornを起動しようと下記のコマンドを入力したら、エラーとなってしまいました。

入力

bundle exec unicorn_rails -c /var/www/projects/drink-app-rb/config/unicorn.conf.rb -D -E production

エラー

bundler: failed to load command: unicorn_rails (/var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/bin/unicorn_rails)
NameError: uninitialized constant AppName
  config.ru:6:in `block in <main>'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/gems/rack-2.0.3/lib/rack/builder.rb:55:in `instance_eval'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/gems/rack-2.0.3/lib/rack/builder.rb:55:in `initialize'
  config.ru:1:in `new'
  config.ru:1:in `<main>'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/gems/unicorn-5.4.0/lib/unicorn.rb:56:in `eval'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/gems/unicorn-5.4.0/lib/unicorn.rb:56:in `block in builder'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/gems/unicorn-5.4.0/bin/unicorn_rails:139:in `block in rails_builder'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/gems/unicorn-5.4.0/lib/unicorn/http_server.rb:795:in `build_app!'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/gems/unicorn-5.4.0/lib/unicorn/http_server.rb:139:in `start'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/gems/unicorn-5.4.0/bin/unicorn_rails:209:in `<top (required)>'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/bin/unicorn_rails:23:in `load'
  /var/www/projects/drink-app-rb/vendor/bundle/ruby/2.4.0/bin/unicorn_rails:23:in `<top (required)>'

unicorn.conf.rb

# set lets
$worker  = 2
$timeout = 30
$app_dir = '/var/www/projects/drink-app-rb'
$listen  = File.expand_path 'tmp/sockets/.unicorn.sock', $app_dir
$pid     = File.expand_path 'tmp/pids/unicorn.pid', $app_dir
$std_log = File.expand_path 'log/unicorn.log', $app_dir
# set config
worker_processes  $worker
working_directory $app_dir
stderr_path $std_log
stdout_path $std_log
timeout $timeout
listen  $listen
pid $pid
# loading booster
preload_app true
# before starting processes
before_fork do |server, worker|
  defined?(ActiveRecord::Base) and ActiveRecord::Base.connection.disconnect!
  old_pid = "#{server.config[:pid]}.oldbin"
  if old_pid != server.pid
    begin
      Process.kill "QUIT", File.read(old_pid).to_i
    rescue Errno::ENOENT, Errno::ESRCH
    end
  end
end
# after finishing processes
after_fork do |server, worker|
  defined?(ActiveRecord::Base) and ActiveRecord::Base.establish_connection
end

nginxの設定

upstream unicorn_server {
    server unix:/var/www/projects/drink-app-rb/tmp/sockets/.unicorn.sock
    fail_timeout=0;
}

server {
    listen 80;
    client_max_body_size 4G;
    server_name www.drink-app.club;

    #Basic
    auth_basic "basic auth";
    auth_basic_user_file /etc/nginx/.htpasswd;

    keepalive_timeout 5;

    # Location of our static files
    root /var/www/projects/drink-app-rb/public;

    location ~ ^/assets/ {
        root /var/www/projects/drink-app-rb/public;
    }

    location / {
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header Host $http_host;
        proxy_redirect off;

        if (!-f $request_filename) {
            proxy_pass http://unicorn_server;
            break;
        }
    }

    error_page 500 502 503 504 /500.html;
    location = /500.html {
        root /var/www/projects/drink-app-rb/public;
    }
}

アドバイスいただけると助かります。よろしくお願いします。

情報不足しておりましたら、ご指摘もおねがいします