開発環境では問題なく動いていたアプリが、満を持してデプロイしたときにクラッシュしてたら精神的に結構きますよね
正直、辛い。
今回は、Rails5のアプリをHerokuにデプロイした際にクラッシュを起こしていたので、そのとき取った行動をメモとして残しておきます。
#エラー画面
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If you are the application owner check the logs for more information.
日本語でおｋ（死語）
このエラー文自体を検索し、色んなエラー時対応の記事を読み込んでいくと、
何にしろログを見なっせ（書いてある）ということなので、
$ heroku logsを叩きました。
こちらの記事はとても参考になりました。
Qiita/[Ruby on Rails Tutorial]Herokuにデプロイ後Application error[H10 (App crashed)]が発生した時の対処法
$ heroku logs
2020-02-19T13:24:10.854459+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/runner.rb:138:in `load_and_bind'
2020-02-19T13:24:10.854460+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/single.rb:87:in `run'
2020-02-19T13:24:10.854460+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/launcher.rb:174:in `run'
2020-02-19T13:24:10.854461+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/cli.rb:77:in `run'
2020-02-19T13:24:10.854461+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/bin/puma:10:in `<top (required)>'
2020-02-19T13:24:10.854462+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/bin/puma:23:in `load'
2020-02-19T13:24:10.854462+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/bin/puma:23:in `<top (required)>'
2020-02-19T13:24:10.941495+00:00 heroku[web.1]: State changed from starting to crashed
2020-02-19T13:24:10.946163+00:00 heroku[web.1]: State changed from crashed to starting
2020-02-19T13:24:10.919655+00:00 heroku[web.1]: Process exited with status 1
2020-02-19T13:24:14.912178+00:00 heroku[web.1]: Starting process with command `bundle exec puma -C config/puma.rb`
2020-02-19T13:24:17.577966+00:00 app[web.1]: Puma starting in single mode...
2020-02-19T13:24:17.587312+00:00 app[web.1]: * Version 3.9.1 (ruby 2.5.7-p206), codename: Private Caller
2020-02-19T13:24:17.587332+00:00 app[web.1]: * Min threads: 5, max threads: 5
2020-02-19T13:24:17.587335+00:00 app[web.1]: * Environment: production
2020-02-19T13:24:19.870761+00:00 app[web.1]: ! Unable to load application: LoadError: No such file to load -- URI.rb
2020-02-19T13:24:19.870872+00:00 app[web.1]: bundler: failed to load command: puma (/app/vendor/bundle/ruby/2.5.0/bin/puma)
2020-02-19T13:24:19.870924+00:00 app[web.1]: LoadError: No such file to load -- URI.rb
2020-02-19T13:24:19.870926+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
2020-02-19T13:24:19.870926+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
2020-02-19T13:24:19.870927+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
2020-02-19T13:24:19.870927+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
2020-02-19T13:24:19.870928+00:00 app[web.1]: /app/app/controllers/application_controller.rb:5:in `<class:ApplicationController>'
2020-02-19T13:24:19.870928+00:00 app[web.1]: /app/app/controllers/application_controller.rb:1:in `<top (required)>'
2020-02-19T13:24:19.870929+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
2020-02-19T13:24:19.870929+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `block in require'
2020-02-19T13:24:19.870930+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in `load_dependency'
2020-02-19T13:24:19.870930+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in `require'
2020-02-19T13:24:19.870930+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:379:in `block in require_or_load'
2020-02-19T13:24:19.870931+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:36:in `block in load_interlock'
2020-02-19T13:24:19.870931+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies/interlock.rb:12:in `block in loading'
2020-02-19T13:24:19.870932+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/concurrency/share_lock.rb:149:in `exclusive'
2020-02-19T13:24:19.870932+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies/interlock.rb:11:in `loading'
2020-02-19T13:24:19.870933+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:36:in `load_interlock'
2020-02-19T13:24:19.870933+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:357:in `require_or_load'
2020-02-19T13:24:19.870934+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:335:in `depend_on'
2020-02-19T13:24:19.870934+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:251:in `require_dependency'
2020-02-19T13:24:19.870934+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/engine.rb:476:in `block (2 levels) in eager_load!'
2020-02-19T13:24:19.870935+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/engine.rb:475:in `each'
2020-02-19T13:24:19.870935+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/engine.rb:475:in `block in eager_load!'
2020-02-19T13:24:19.870935+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/engine.rb:473:in `each'
2020-02-19T13:24:19.870936+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/engine.rb:473:in `eager_load!'
2020-02-19T13:24:19.870936+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/engine.rb:354:in `eager_load!'
2020-02-19T13:24:19.870937+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/application/finisher.rb:67:in `each'
2020-02-19T13:24:19.870937+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/application/finisher.rb:67:in `block in <module:Finisher>'
2020-02-19T13:24:19.870937+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/initializable.rb:30:in `instance_exec'
2020-02-19T13:24:19.870938+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/initializable.rb:30:in `run'
2020-02-19T13:24:19.870938+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/initializable.rb:59:in `block in run_initializers'
2020-02-19T13:24:19.870939+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:228:in `block in tsort_each'
2020-02-19T13:24:19.870939+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:350:in `block (2 levels) in each_strongly_connected_component'
2020-02-19T13:24:19.870939+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:431:in `each_strongly_connected_component_from'
2020-02-19T13:24:19.870940+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:349:in `block in each_strongly_connected_component'
2020-02-19T13:24:19.870940+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:347:in `each'
2020-02-19T13:24:19.870941+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:347:in `call'
2020-02-19T13:24:19.870941+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:347:in `each_strongly_connected_component'
2020-02-19T13:24:19.870942+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:226:in `tsort_each'
2020-02-19T13:24:19.870942+00:00 app[web.1]: /app/vendor/ruby-2.5.7/lib/ruby/2.5.0/tsort.rb:205:in `tsort_each'
2020-02-19T13:24:19.870947+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/initializable.rb:58:in `run_initializers'
2020-02-19T13:24:19.870947+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/railties-5.1.6/lib/rails/application.rb:353:in `initialize!'
2020-02-19T13:24:19.870948+00:00 app[web.1]: /app/config/environment.rb:5:in `<top (required)>'
2020-02-19T13:24:19.870948+00:00 app[web.1]: config.ru:3:in `require_relative'
2020-02-19T13:24:19.870948+00:00 app[web.1]: config.ru:3:in `block in <main>'
2020-02-19T13:24:19.870949+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/rack-2.2.2/lib/rack/builder.rb:116:in `eval'
2020-02-19T13:24:19.870949+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/rack-2.2.2/lib/rack/builder.rb:116:in `new_from_string'
2020-02-19T13:24:19.870950+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/rack-2.2.2/lib/rack/builder.rb:105:in `load_file'
2020-02-19T13:24:19.870950+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/rack-2.2.2/lib/rack/builder.rb:66:in `parse_file'
2020-02-19T13:24:19.870951+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/configuration.rb:313:in `load_rackup'
2020-02-19T13:24:19.870951+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/configuration.rb:242:in `app'
2020-02-19T13:24:19.870951+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/runner.rb:138:in `load_and_bind'
2020-02-19T13:24:19.870952+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/single.rb:87:in `run'
2020-02-19T13:24:19.870952+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/launcher.rb:174:in `run'
2020-02-19T13:24:19.870952+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/lib/puma/cli.rb:77:in `run'
2020-02-19T13:24:19.870952+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/gems/puma-3.9.1/bin/puma:10:in `<top (required)>'
2020-02-19T13:24:19.870953+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/bin/puma:23:in `load'
2020-02-19T13:24:19.870953+00:00 app[web.1]: /app/vendor/bundle/ruby/2.5.0/bin/puma:23:in `<top (required)>'
2020-02-19T13:24:20.204439+00:00 heroku[web.1]: State changed from starting to crashed
2020-02-19T13:24:20.185683+00:00 heroku[web.1]: Process exited with status 1
2020-02-19T13:24:21.120419+00:00 heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/" host=example.herokuapp.com request_id=eb4b6551-949a-4693-9f76-2b0bcd0e92dd fwd="219.100.188.52" dyno= connect= service= status=503 bytes= protocol=https
心折れそう
折れてました。
辛かったので、エラー文の一番最後にあった
heroku[router]: at=error code=H10 desc="App crashed" method=GET path="/"
を、エラーコード記載されてるし後はグーグル先生がどうにかしてくれるだろうと脳死で検索しました。
結果的に分かったのは、
#エラー文見ろ
厳しい！！！
目から溢れる汁で滲む画面を読み進めたところ、次の部分に目が留まる（とはいっても序盤の方）。
2020-02-19T13:24:19.870761+00:00 app[web.1]: ! Unable to load application: LoadError: No such file to load -- URI.rb
2020-02-19T13:24:19.870872+00:00 app[web.1]: bundler: failed to load command: puma (/app/vendor/bundle/ruby/2.5.0/bin/puma)
2020-02-19T13:24:19.870924+00:00 app[web.1]: LoadError: No such file to load -- URI.rb
ご丁寧に！までつけてある。
ここでピーンと来て、そういえばネットから次のコードをコピペしたときに、
example_controller.rb
require 'net/https'
require 'uri' # 'URI'と記載していた
で実行したところ、uriなんてねえよバーカ！と怒られたので、
'uri'=>'URI'と訂正したことを思い出しました。
お ま え か。
その後、正しくrequire 'uri'と訂正すると無事動いてくれました。
#エラー文を読もう（結論）
心折れかかったら息抜きも忘れないでください。