capistrano/docs/documentation/getting-started/user-input/index.markdown

title	layout
User Input	default

User input can be required in a task or during configuration:

# used in a configuration
set :database_name, ask('Enter the database name:')

# used in a task
desc "Ask about breakfast"
task :breakfast do
  ask(:breakfast, "pancakes")
  on roles(:all) do |h|
    execute "echo \"$(whoami) wants #{fetch(:breakfast)} for breakfast!\""
  end
end

When using ask to get user input, you can pass echo: false to prevent the input from being displayed. This option should be used to ask the user for passwords and other sensitive data during a deploy run.

set :database_password, ask('Enter the database password:', 'default', echo: false)

If you only pass in a symbol this will be printed as text for the user and the input will be saved to this variable:

ask(:database_encoding, 'UTF-8')

fetch(:database_encoding)
# => contains the user input (or the default)
#    once the above line got executed

You can use ask to set a server- or role-specific configuration variable.

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