I've been struggling with this question: how can I hide passwords from my source code, that everyone can see on github, for example:
ActionMailer::Base.smtp_settings = {
:address => "smtp.gmail.com",
:port => 587,
:user_name => my_user_name,
:password => my_password,
:authentication => 'plain',
:enable_starttls_auto => true,
:domain => 'gmail.com'
}