capistrano/documentation/getting-started/password-authentication/index.markdown

title	layout
Password Authentication	default

Password authentication can be done via set and ask in your deploy environment file (e.g.: config/deploy/production.rb)

set :password, ask('Server password', nil)
server 'server.domain.com', user: 'ssh_user_name', port: 22, password: fetch(:password), roles: %w{web app db}