script to update a google cloud dns record for a host

update_dns.py

#!/usr/bin/env python3
"""Update Google cloud dns records for a machine."""
# if testing locally, make sure that you have authenticated: https://googlecloudplatform.github.io/google-cloud-python/stable/google-cloud-auth.html#overview
from google.cloud import dns

def update_dns_a_record(zonename, hostname, ip_address):
    """Update the A record for a given host on a target zone."""
    client = dns.Client()
    zone = client.zone(zonename)
    zone.reload()  # call api to populate zone attributes
    
    fq_hostname = '{host}.{domain}'.format(host=hostname, domain=zone.dns_name)
    
    # start a change transaction
    change_set = zone.changes()  
    
    # remove existing records
    for record in zone.list_resource_record_sets():
        if record.name == fq_hostname:
            change_set.delete_record_set(record)
            
    # add new record
    new_record = zone.resource_record_set(
        name=fq_hostname,
        record_type='A',
        ttl=300,
        rrdatas=[ip_address],
    )
    change_set.add_record_set(new_record)
    
    # asynchronously commit change transaction
    change_set.create()
    
    
def main():
    zonename = 'test-zone'
    hostname = 'hostname'
    ipaddr = '10.0.0.100'
    update_dns_a_record(zonename, hostname, ipaddr)


if __name__ == '__main__':
    main()

Note, this hasn't been fully tested or debugged.