4_netmiko_seek_helper_addrs.py

# pip install --user netmiko
from netmiko import Netmiko
from ciscoconfparse import CiscoConfParse

username = "clab"
password = "clab@123"
device_type = "cisco_xr"
hosts = ["172.16.x.2", "172.16.x.3", "172.16.x.4"]  # TODO
target_ip_helper = "fill me in!"

for host in hosts:
    # Create a variable that represents an SSH connection to our router.
    connection = Netmiko(
        username=username, password=password, device_type=device_type, ip=host
    )

    # Get the output for "show run". This will be raw and unformatted.
    raw_config = connection.send_command("show run")

    # Turn this giant singular string of output into a list of lines.
    parser = CiscoConfParse(raw_config.split("\n"))

    for intf in parser.find_objects("^interface .*"):
        # Get the interface name.
        intf_name = intf.text

        # Give us nice messages
        print(f"Inspecting {intf_name} on {host}...")

        # Retrieve the helper address, if it exists.
        helper_address_line = intf.re_search_children("^ ipv4 helper-address")
        if not helper_address_line:
            # Nothing to see here! Skip.
            # Don't configure a new IP helper on interfaces that don't have one.
            continue

        # Get the last "word" in the line, which is the helper IP address.
        ip = helper_address_line[-1]

        if ip != target_ip_helper:
            print(f"Found old IP helper!:\n{intf}")
            commands = [
                intf_name,
                f"no ipv4 helper-address {ip}",
                f"ipv4 helper-address {target_ip_helper}",
                "commit"
            ]
            # Let's observe:
            print(f"Running: {commands}")
            connection.send_config_set(commands)
            new_interface_config = connection.send_command(f"show run int {intf_name}")
            print(f"Post-configuration:\n{new_interface_config}")

print("Done!")