code: def cmd_ssh(self, argv, help):
          
          parser = argparse.ArgumentParser(
              prog="%s ssh" % self.progname,
              description=help,
          )
          instances = self.get_instances(command='init_ssh_key')
          parser.add_argument("instance", nargs=1,
                              metavar="instance",
                              help="Name of the instance from the config.",
                              choices=sorted(instances))
          parser.add_argument("...", nargs=argparse.REMAINDER,
                              help="ssh options")
          iargs = enumerate(argv)
          sid_index = None
          user = None
          for i, arg in iargs:
              if not arg.startswith('-'):
                  sid_index = i
                  break
              if arg[1] in '1246AaCfgKkMNnqsTtVvXxYy':
                  continue
              elif arg[1] in 'bcDeFiLlmOopRSw':
                  value = iargs.next()
                  if arg[1] == 'l':
                      user = value[1]
                  continue
          # fake parsing for nice error messages
          if sid_index is None:
              parser.parse_args([])
          else:
              sid = argv[sid_index]
              if '@' in sid:
                  user, sid = sid.split('@', 1)
              parser.parse_args([sid])
          instance = instances[sid]
          if user is None:
              user = instance.config.get('user')
          try:
              ssh_info = instance.init_ssh_key(user=user)
          except (instance.paramiko.SSHException, socket.error) as e:
              log.error("Couldn't validate fingerprint for ssh connection.")
              log.error(unicode(e))
              log.error("Is the instance finished starting up?")
              sys.exit(1)
          client = ssh_info['client']
          client.get_transport().sock.close()
          client.close()
          argv[sid_index:sid_index + 1] = instance.ssh_args_from_info(ssh_info)
          argv[0:0] = ['ssh']
          os.execvp('ssh', argv)
docs: Log into the instance with ssh using the automatically generated known hosts