Rails5をproduction（本番環境）で起動する時に嵌ったこと ref: https://qiita.com/qiugits/items/7cd01f4b5cff4a31e053

(A).

$ export SECRET_KEY_BASE=`bundle exec rake secret`

file3.txt

$ export -p | grep SECRET_KEY_BASE
declare -x SECRET_KEY_BASE="Could not locate Gemfile or .bundle/ directory"

production.rb

config.assets.compile = true

secrets.yml

development:
  secret_key_base: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

test:
  secret_key_base: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

# Do not keep production secrets in the repository,
# instead read values from the environment.
production:
  secret_key_base: <%= ENV["SECRET_KEY_BASE"] %>