Simple DDNS add/update/remove script

dns_update.py

import argparse
import subprocess
import os

DNS_server = "x.x.x.x"
DNS_zone = "zone_name.com"
DNS_key_fullpath = "/path/to/.private_file"

parser = argparse.ArgumentParser(description='Add/Modify or remove DNS entries')
parser.add_argument('-r',
        '--remove',
        help='Remove DNS record from the server.',
        action='store_true',
        required=False)
parser.add_argument('-a',
        '--add',
        help='Add DNS record to the server.',
        action='store_true',
        required=False)
parser.add_argument('-n',
        '--name',
        help='The FQDN of the server to add or remove.',
        type=str,
        required=True)
parser.add_argument('-i',
        '--ip',
        help='The IP address of the server to add.',
        type=str,
        required=False)


args = parser.parse_args()
DNS_str = ""

if (args.add and args.remove):
    print("Can't add and remove")
    exit(1)

if args.add:
    if args.ip is None:
        print("Must have IP to add.")
        exit(1)
    DNS_str = """
server {0}
zone {1}
update delete {2}. A
update add {2}. 3600 A {3}
send
""".format(DNS_server, DNS_zone, args.name, args.ip)

if args.remove:
    DNS_str = """
server {0}
zone {1}
update delete {2}. A
send
""".format(DNS_server, DNS_zone, args.name)

DNS_str = DNS_str.lstrip()

tmpFile = open("tmp.dns", "w")
tmpFile.write(DNS_str)
tmpFile.close()
subprocess.call(["nsupdate", "-k", "DNS_key_fullpath", "tmp.dns"])
os.remove("tmp.dns")