Herokuにbuildするとエラーが出てしまいます。

Question

rails tutorialの第12章を進め、最後の方でHerokuにデプロイしようとしたらこのようなエラーが起こってしまいました。調べてみても解決せずどうすればいいか分かりません。どなたかわかる方助けて頂きたいです。よろしくお願いします。

--> Building on the Heroku-20 stack
-----> Ruby app detected
-----> Installing bundler 1.17.3
-----> Removing BUNDLED WITH version in the Gemfile.lock
-----> Compiling Ruby/Rails
-----> Using Ruby version: ruby-2.6.6
-----> Installing dependencies using bundler 1.17.3
Running: BUNDLE_WITHOUT='development:test' BUNDLE_PATH=vendor/bundle BUNDLE_BIN=vendor/bundle/bin BUNDLE_DEPLOYMENT=1 BUNDLE_GLOBAL_PATH_APPENDS_RUBY_SCOPE=1 bundle install -j4
The dependency tzinfo-data (>= 0) will be unused by any of the platforms Bundler is installing for. Bundler is installing for ruby but the dependency is only for x86-mingw32, x86-mswin32, x64-mingw32, java. To add those platforms to the bundle, run bundle lock --add-platform x86-mingw32 x86-mswin32 x64-mingw32 java.
Using rake 13.0.3
Using concurrent-ruby 1.1.8
Using i18n 0.9.5
Using minitest 5.10.3
Using thread_safe 0.3.6
Using tzinfo 1.2.9
Using activesupport 5.1.6
Using builder 3.2.4
Using erubi 1.10.0
Using mini_portile2 2.5.0
Using racc 1.5.2
Using nokogiri 1.11.1 (x86_64-linux)
Using rails-dom-testing 2.0.3
Using crass 1.0.6
Using loofah 2.9.0
Using rails-html-sanitizer 1.3.0
Using actionview 5.1.6
Using rack 2.2.3
Using rack-test 1.1.0
Using actionpack 5.1.6
Using nio4r 2.5.7
Using websocket-extensions 0.1.5
Using websocket-driver 0.6.5
Using actioncable 5.1.6
Using globalid 0.4.2
Using activejob 5.1.6
Using mini_mime 1.0.2
Using mail 2.7.1
Using actionmailer 5.1.6
Using activemodel 5.1.6
Using arel 8.0.0
Using activerecord 5.1.6
Using execjs 2.7.0
Using autoprefixer-rails 10.2.4.0
Using bcrypt 3.1.12
Using rb-fsevent 0.10.4
Using ffi 1.15.0
Using rb-inotify 0.10.1
Using sass-listen 4.0.0
Using sass 3.7.4
Using bootstrap-sass 3.3.7
Using will_paginate 3.1.6
Using bootstrap-will_paginate 1.0.0
Using bundler 1.17.3
Using coffee-script-source 1.12.2
Using coffee-script 2.4.1
Using method_source 1.0.0
Using thor 1.1.0
Using railties 5.1.6
Using coffee-rails 4.2.2
Using faker 1.7.3
Using multi_json 1.15.0
Using jbuilder 2.7.0
Using jquery-rails 4.3.1
Using pg 0.20.0
Using puma 3.9.1
Using sprockets 3.7.2
Using sprockets-rails 3.2.2
Using rails 5.1.6
Using tilt 2.0.10
Using sass-rails 5.0.6
Using turbolinks-source 5.2.0
Using turbolinks 5.0.1
Using uglifier 3.2.0
Bundle complete! 26 Gemfile dependencies, 64 gems now installed.
Gems in the groups development and test were not installed.
Bundled gems are installed into ./vendor/bundle
Bundle completed (0.56s)
Cleaning up the bundler cache.
The dependency tzinfo-data (>= 0) will be unused by any of the platforms Bundler is installing for. Bundler is installing for ruby but the dependency is only for x86-mingw32, x86-mswin32, x64-mingw32, java. To add those platforms to the bundle, run bundle lock --add-platform x86-mingw32 x86-mswin32 x64-mingw32 java.
-----> Installing node-v12.16.2-linux-x64
-----> Detecting rake tasks
-----> Preparing app for Rails asset pipeline
Running: rake assets:precompile
rake aborted!
NameError: undefined local variable or method smtp' for #<SampleApp::Application:0x000055cfcd194ec8> /tmp/build_8e114bc7/config/environments/production.rb:73:in block in <top (required)>'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/railtie.rb:211:in instance_eval' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/railtie.rb:211:in configure'
/tmp/build_8e114bc7/config/environments/production.rb:1:in <top (required)>' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in require'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in block in require' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:258:in load_dependency'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/activesupport-5.1.6/lib/active_support/dependencies.rb:292:in require' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/engine.rb:600:in block (2 levels) in class:Engine'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/engine.rb:599:in each' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/engine.rb:599:in block in class:Engine'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/initializable.rb:30:in instance_exec' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/initializable.rb:30:in run'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/initializable.rb:59:in block in run_initializers' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/initializable.rb:48:in each'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/initializable.rb:48:in tsort_each_child' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/initializable.rb:58:in run_initializers'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/application.rb:353:in initialize!' /tmp/build_8e114bc7/config/environment.rb:5:in <top (required)>'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/application.rb:329:in require' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/application.rb:329:in require_environment!'
/tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/railties-5.1.6/lib/rails/application.rb:445:in block in run_tasks_blocks' /tmp/build_8e114bc7/vendor/bundle/ruby/2.6.0/gems/sprockets-rails-3.2.2/lib/sprockets/rails/task.rb:61:in block (2 levels) in define'
Tasks: TOP => environment
(See full trace by running task with --trace)
!
! Precompiling assets failed.
!
! Push rejected, failed to compile Ruby app.
! Push failed

Comments

[maisumakun]

「config/environments/production.rb:73」でエラーが発生したと書かれていますが、この周辺の内容はどのようになっていますか？

（環境ごとの設定ファイルなので、productionにしない限りはこのファイルを読まれることもありません）

[blacksmoke]

ご回答ありがとうございます！
このような内容になっています。
config.action_mailer.raise_delivery_errors = true
config.action_mailer.delivery_method = :smtp
host = 'https://warm-brushlands-70219.herokuapp.com'
config.action_mailer.default_url_options = { host: host }
ActionMailer::Base.smtp_settings = {
:port => 587,
:address => smtp.mailgun.org,
:user_name => ENV['[e-mail]'],
:password => ENV['db6da2a4e8d6ad953cf9957dc2d9a560-29561299-ce25e9b5'],
:domain => host,
:authentication => :plain,
}

[maisumakun]

ユーザーIDやパスワードは隠しておいたほうがいいです。

[blacksmoke]

ありがとうございます！初歩的なミスでお恥ずかしいです。アドバイスもありがとうございますm(__)m

Answer 1

:address => smtp.mailgun.org,

引用符なしで書いたために、smtpを変数名あるいはメソッドとして解釈しようとしたものの、存在しないためにエラーとなっています。