Tasks to apply changes

[sec0uth]

Branch changes-modules-#15

Description

Once connected to Juno device, registered tasks can manage the device directly supplied by user configuration.

Specification

Full code of AbstractTask.

Note: truncated content for brevity

class AbstractTask(ABC, Util):
    """Abstraction layer for creating a task on Juniper devices."""

    def __init__(self, device: Device, config: dict) -> None:
        """Class constructor."""
        ...

    @abstractmethod
    def run(self) -> None:
        """Start task."""
        pass

    def pre_start(self) -> None:
        """
        Initialize task before actually starting it.

        Subclasses may override this method. 
        """
        pass

The main methods is run() and pre_start(), the latter may be used by subclasses to validate a custom configuration, for example. The state of the application when calling such methods is the following:

• pre_start : called first, for each task. The device attribute, which is a local variable, is not connected yet, this allows changing the device configuration dynamically. In the following code extracted from SSHPassword task, it asks for user ssh password and set in the device:

  def pre_start(self):
  """Ask password when needed."""
  ssh_config = self.config['ssh']
  
  needs_passwd = ssh_config.get('passwd') is None and \
                  ssh_config.get('ask_passwd') is True
  
  if needs_passwd:
      # ask user password
      ssh_passwd = getpass.getpass(prompt='SSH password:')
  
      # set auth password
      self.dev._auth_password = ssh_passwd

  • run : abstract method that should have an implementation on subclasses. When called, the device is connected and ready.