Proposed SSH DSL for Ruby

proposed-ssh-dsl-for-ruby.rb

#
# Please read the examples inline thoroughly, these comprise some of the proposed
# DSLs for a better SSH Ruby SSH driver, upon which people can build decent tools
#
servers     = %w( example.com beispeil.de ejemplo.es )
environment = {rails_env: production, rack_env: production}

LibSSH.configure do |config|

  #
  # Connection Timeout
  #
  config.connection_timeout = 10.seconds

  #
  # Connection "handler" - replacable
  # if you don't need to raise an exception
  # when a host times out
  #
  config.timeout_handler = lambda do
    raise LibSSH::ConnectionTimeoutError
  end

  #
  # Pool, and reuse connections to servers
  # where possible
  #
  config.connection_pooling = true

  #
  # Send a default environment hash, where possible
  #
  config.default_environment = environment

  #
  # An interactive terminal (or PTY) is a connection
  # that behaves like a user, sitting at a terminal
  # programs running in a PTY expect to be able to 
  # prompt the user for feedback and input.
  # Shells, for example typically use the presence
  # of a PTY to justify loading a user's dotfiles
  #
  config.prefer_interative_terminal = true

  #
  # Default shell configutation
  #
  config.default_shell = 'sh'

end

#
# Runs "hostname" on one host, echos the result locally
#
on servers.first do
  puts remote("hostname")
end

#
# Demonstrates connecting in parallel to two servers, and 
# writing the result, IO#print is used because of thread 
# safety
#
on servers[0..2] do
  in "/etc/" do
    remote("ls").each_line do |line|
      print line + "\n"
    end
  end
end

#
# Change a user's password, includes some trimmings
#
responder = lambda do |prompt|
  "MyAwesomePassword" if prompt =~ /Password:/
end
on servers.first do 
  as "root", :with => responder do
    if run("passwd anotheruser", "User'sNewPassword")
      puts "Changed 'anotheruser's Password Successfully"
    else
      puts "There was an error changing the other user's password #{exit_status}"
    end
  end
end

#
# Operates on all four servers, in sequence
# waiting 5 seconds between each operation
# does not have to concern itself with thread safety
#
on servers, :in => :sequence, :wait => 5 do
  in "/var/www" do
    with {queue: '*'} do
      unless run("service resque restart")
        # Break unless we can restart the server
        break
      end
    end
  end
end

I agree that on, in and run do read well, it was more that I could not think of what function/behavior they provide/facilitate.