Example of simple file to centralize User management

seeds.rb

users_file = Rails.root.join('storage', 'users.yml.erb')
if File.exist? users_file
  users = YAML.load(ERB.new(File.read(users_file)).result)

  User.insert_all(
    users.map { |user| user.except("password") },
    unique_by: :username
  )
end

users.yml.erb

<%
  def digest(username, password)
    ActionController::HttpAuthentication::Digest.ha1(
      {
        username: username,
        realm: Rails.application.credentials.auth_realm
      },
      password
    )
  end
%>

---
- username: spm
  email: stephen@margheim.com
  password: 'mypassword'
  password_digest: <%= digest("spm", "mypassword") %>