仮想マシンでRuby on Railsをサーバー起動する

使用環境
・Rails 6.0.0
・vagrant
・

問題

下記のようにRailsアプリフォルダに移動し、myappという名のアプリでサーバー起動しようとしたところ、エラーが発生しました。

ここまでは問題なし

```
$cd
$cd MyVagrant
$cd vagrant ssh
$cd rails_lessons
$cd myapp
```

このコマンドでエラー発生

```
$cd rails server -b /*サーバーのIPアドレス*/ -d
```

こんなエラー

```
=> Booting Puma
=> Rails 6.0.0 application starting in development 
=> Run `rails server --help` for more startup options
RAILS_ENV=development environment is not defined in config/webpacker.yml, falling back to production environment
Traceback (most recent call last):
	80: from bin/rails:3:in `<main>'
	79: from bin/rails:3:in `load'
	78: from /home/vagrant/rails_lessons/myapp/bin/spring:15:in `<top (required)>'
	77: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
	76: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
	75: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/binstub.rb:11:in `<top (required)>'
	74: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/binstub.rb:11:in `load'
	73: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/bin/spring:49:in `<top (required)>'
	72: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/client.rb:30:in `run'
	71: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/client/command.rb:7:in `call'
	70: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/client/rails.rb:28:in `call'
	69: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/client/rails.rb:28:in `load'
	68: from /home/vagrant/rails_lessons/myapp/bin/rails:9:in `<top (required)>'
	67: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:325:in `require'
	66: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:291:in `load_dependency'
	65: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:325:in `block in require'
	64: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
	63: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
	62: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
	61: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
	60: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
	59: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands.rb:18:in `<main>'
	58: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/command.rb:46:in `invoke'
	57: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/command/base.rb:65:in `perform'
	56: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor.rb:387:in `dispatch'
	55: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor/invocation.rb:126:in `invoke_command'
	54: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor/command.rb:27:in `run'
	53: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands/server/server_command.rb:138:in `perform'
	52: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands/server/server_command.rb:138:in `tap'
	51: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands/server/server_command.rb:147:in `block in perform'
	50: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands/server/server_command.rb:39:in `start'
	49: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/server.rb:283:in `start'
	48: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/server.rb:354:in `wrapped_app'
	47: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/server.rb:219:in `app'
	46: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/server.rb:319:in `build_app_and_options_from_config'
	45: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:40:in `parse_file'
	44: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:49:in `new_from_string'
	43: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:49:in `eval'
	42: from config.ru:in `<main>'
	41: from config.ru:in `new'
	40: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:55:in `initialize'
	39: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:55:in `instance_eval'
	38: from config.ru:3:in `block in <main>'
	37: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:48:in `require_relative'
	36: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:325:in `require'
	35: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:291:in `load_dependency'
	34: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:325:in `block in require'
	33: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/zeitwerk-2.2.0/lib/zeitwerk/kernel.rb:23:in `require'
	32: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
	31: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
	30: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
	29: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
	28: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
	27: from /home/vagrant/rails_lessons/myapp/config/environment.rb:5:in `<main>'
	26: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/application.rb:363:in `initialize!'
	25: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/initializable.rb:60:in `run_initializers'
	24: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:205:in `tsort_each'
	23: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:226:in `tsort_each'
	22: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:347:in `each_strongly_connected_component'
	21: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:347:in `call'
	20: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:347:in `each'
	19: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:349:in `block in each_strongly_connected_component'
	18: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:431:in `each_strongly_connected_component_from'
	17: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
	16: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:228:in `block in tsort_each'
	15: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/initializable.rb:61:in `block in run_initializers'
	14: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/initializable.rb:32:in `run'
	13: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/initializable.rb:32:in `instance_exec'
	12: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/railtie.rb:84:in `block in <class:Engine>'
	11: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker.rb:27:in `bootstrap'
	10: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/commands.rb:14:in `bootstrap'
	 9: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/manifest.rb:18:in `refresh'
	 8: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/manifest.rb:83:in `load'
	 7: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:47:in `public_manifest_path'
	 6: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:43:in `public_output_path'
	 5: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:39:in `public_path'
	 4: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:80:in `fetch'
	 3: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:84:in `data'
	 2: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:88:in `load'
	 1: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:88:in `read'
/home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:88:in `read': No such file or directory @ rb_sysopen - /home/vagrant/rails_lessons/myapp/config/webpacker.yml (Errno::ENOENT)
	79: from bin/rails:3:in `<main>'
	78: from bin/rails:3:in `load'
	77: from /home/vagrant/rails_lessons/myapp/bin/spring:15:in `<top (required)>'
	76: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
	75: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/rubygems/core_ext/kernel_require.rb:54:in `require'
	74: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/binstub.rb:11:in `<top (required)>'
	73: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/binstub.rb:11:in `load'
	72: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/bin/spring:49:in `<top (required)>'
	71: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/client.rb:30:in `run'
	70: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/client/command.rb:7:in `call'
	69: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/client/rails.rb:28:in `call'
	68: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/spring-2.1.0/lib/spring/client/rails.rb:28:in `load'
	67: from /home/vagrant/rails_lessons/myapp/bin/rails:9:in `<top (required)>'
	66: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:325:in `require'
	65: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:291:in `load_dependency'
	64: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:325:in `block in require'
	63: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
	62: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
	61: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
	60: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
	59: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
	58: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands.rb:18:in `<main>'
	57: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/command.rb:46:in `invoke'
	56: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/command/base.rb:65:in `perform'
	55: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor.rb:387:in `dispatch'
	54: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor/invocation.rb:126:in `invoke_command'
	53: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/thor-0.20.3/lib/thor/command.rb:27:in `run'
	52: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands/server/server_command.rb:138:in `perform'
	51: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands/server/server_command.rb:138:in `tap'
	50: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands/server/server_command.rb:147:in `block in perform'
	49: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/commands/server/server_command.rb:39:in `start'
	48: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/server.rb:283:in `start'
	47: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/server.rb:354:in `wrapped_app'
	46: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/server.rb:219:in `app'
	45: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/server.rb:319:in `build_app_and_options_from_config'
	44: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:40:in `parse_file'
	43: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:49:in `new_from_string'
	42: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:49:in `eval'
	41: from config.ru:in `<main>'
	40: from config.ru:in `new'
	39: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:55:in `initialize'
	38: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/rack-2.0.7/lib/rack/builder.rb:55:in `instance_eval'
	37: from config.ru:3:in `block in <main>'
	36: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:48:in `require_relative'
	35: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:325:in `require'
	34: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:291:in `load_dependency'
	33: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/activesupport-6.0.0/lib/active_support/dependencies.rb:325:in `block in require'
	32: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/zeitwerk-2.2.0/lib/zeitwerk/kernel.rb:23:in `require'
	31: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
	30: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:21:in `require_with_bootsnap_lfi'
	29: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/loaded_features_index.rb:92:in `register'
	28: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `block in require_with_bootsnap_lfi'
	27: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/bootsnap-1.4.5/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:22:in `require'
	26: from /home/vagrant/rails_lessons/myapp/config/environment.rb:5:in `<main>'
	25: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/application.rb:363:in `initialize!'
	24: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/initializable.rb:60:in `run_initializers'
	23: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:205:in `tsort_each'
	22: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:226:in `tsort_each'
	21: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:347:in `each_strongly_connected_component'
	20: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:347:in `call'
	19: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:347:in `each'
	18: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:349:in `block in each_strongly_connected_component'
	17: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:431:in `each_strongly_connected_component_from'
	16: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
	15: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/2.6.0/tsort.rb:228:in `block in tsort_each'
	14: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/initializable.rb:61:in `block in run_initializers'
	13: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/initializable.rb:32:in `run'
	12: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/railties-6.0.0/lib/rails/initializable.rb:32:in `instance_exec'
	11: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/railtie.rb:84:in `block in <class:Engine>'
	10: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker.rb:27:in `bootstrap'
	 9: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/commands.rb:14:in `bootstrap'
	 8: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/manifest.rb:18:in `refresh'
	 7: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/manifest.rb:83:in `load'
	 6: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:47:in `public_manifest_path'
	 5: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:43:in `public_output_path'
	 4: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:39:in `public_path'
	 3: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:80:in `fetch'
	 2: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:84:in `data'
	 1: from /home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:87:in `load'
/home/vagrant/.rbenv/versions/2.6.4/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/webpacker/configuration.rb:91:in `rescue in load': Webpacker configuration file not found /home/vagrant/rails_lessons/myapp/config/webpacker.yml. Please run rails webpacker:install Error: No such file or directory @ rb_sysopen - /home/vagrant/rails_lessons/myapp/config/webpacker.yml (RuntimeError)
```

可能性の高い原因としては下の三つ。
1. Webpacker configuration not found 
2. No such file or directory @ rb_sysopen
3. RuntiimeError

まず1を試す。
対処法としては、
`$rails webpacker:install`すると、node.jsをインストールしろってコメントが出てくるので、

このサイトを参考にインストールしした。
https://qiita.com/ffggss/items/94f1c4c5d311db2ec71a

そして、再度下のコメントを入れる
`$rails webpacker:install`

すると今度は、下の表示が出る。

```
Yarn not installed. Please download and install Yarn from https://yarnpkg.com/lang/en/docs/install/
```
下のコマンドを打つ。（参照：https://qiita.com/Kumassy/items/116690fdd99dfc91300d）


`$ curl -sL https://dl.yarnpkg.com/rpm/yarn.repo | sudo tee /etc/yum.repos.d/yarn.repo
$ sudo yum install -y gcc-c++ make yarn git`

と、成功。

```
Webpacker successfully installed 🎉 🍰
```
そして再度、下のコマンド。
`$rails server -b 192.168.33.10 -d`

すると、このように返ってきます。

```
=> Booting Puma
=> Rails 6.0.0 application starting in development 
=> Run `rails server --help` for more startup options
```

本来なら、development以下に、"on IPアドレス"がつくはずです。
このため、rails serverが起動した画面を確認できません。

その理由が不明なので、解消法を探しています。

なお、下のコマンドでバックグラウンドで起動している状態を止めることができたので起動していることは間違いなさそうです。ただ、IPアドレスがわからない。

```
$cat tmp/pids/server.pid
$kill -9 /*番号*/
```