Extend Driver

Occassionally you may have a need that does not fit within one of Napalm’s methods, nor will support ever be expected. As an example, if you wanted to build a parser to filter your unique banner and return structured data from it, you could extend the driver. The positive side effect is that tools such as Salt, Ansible, and Netbox implicitly have access to these methods.

The get_driver method, is simply looking for a custom_napalm.<os> driver first, and then fail to the normal napalm driver.

    module = importlib.import_module("custom_" + module_install_name)
except ImportError:
    module = importlib.import_module(module_install_name)

Extending a Driver

By simply adding custom_napalm folder with an __init__.py and an <os>.py (e.g. ios.py) with class built to inherit the os class, you can expose all of the napalm methods, and your custom ones. This may sound like a lot, but this is here is a simple example of how to inherit the OS driver and all the requirements.

from napalm.ios.ios import IOSDriver
class CustomIOSDriver(IOSDriver):
    """Custom NAPALM Cisco IOS Handler."""
    def get_my_custom_method(self):

Sample python path custom_napalm directory.:

├── __init__.py
└── ios.py

Creating a Custom Method

Bulding on the previous example, we can create a a simple parse to return what our custom enviornment is looking for.

def get_my_banner(self):
    command = 'show banner motd'
    output = self._send_command(command)

    return_vars = {}
    for line in output.splitlines():
        split_line = line.split()
        if "Site:" == split_line[0]:
            return_vars["site"] = split_line[1]
        elif "Device:" == split_line[0]:
            return_vars["device"] = split_line[1]
        elif "Floor:" == split_line[0]:
            return_vars["floor"] = split_line[1]
        elif "Room:" == split_line[0]:
            return_vars["room"] = split_line[1]
    return return_vars

Which can build.

>>> import napalm
>>> ios_device=''
>>> ios_user='ntc'
>>> ios_password='ntc123'
>>> driver = napalm.get_network_driver('ios')
>>> device = driver(ios_device, ios_user, ios_password)
>>> device.open()
>>> device.get_my_banner()
{'device': u'NYC-SW01', 'room': u'1004', 'site': u'NYC', 'floor': u'10'}

Custom Driver Notes

Please note that since there is no base class get_my_banner method, if you attempt to access this method from an os that is not supporting, then it will fail ungracefully. To alleviate that, you can raise NotImplementedError methods in other os’s. It is up to the user to be able to support their own environment.

def get_my_banner(self):
    raise NotImplementedError

This feature is meant to allow for maximum amount of flexibility, but it is up to the user to ensure they do not run into namespace issues, and follow best practices.