~/.bashrc
  source ~/.bashrc

printenv

PRODUCTION_DATABASE_PASSWORD=something

/config/database.yml

production:
    <<: *default
    database: orim
    username: nibble_prod
    password: <%= ENV['PRODUCTION_DATABASE_PASSWORD'] %>

rake db:structure:dump RAILS_ENV=production

/vagrant/vendor/bundle/ruby/2.1.0/gems/mysql2-0.3.19/lib/mysql2/client.rb:70:in `connect': Access denied for user 'nibble_prod'@'localhost' (using password: NO) (Mysql2::Error)