Sketch: #6

The idea is to use a SPOT instance on AWS servers for development to save a buck. However, we need to update the IP of the domain name to the new ip as it changes when it rotates to a new spot instance. This makes it MUCH easier to do.

I need to work on the formatting of the code block, but the base is there for now.

                #!/usr/bin/env python3

import argparse
import http.client as http
import os
import boto3 as aws

def _parse_args(args=None):
    p = argparse.ArgumentParser(description='Update a hostname record in route53 with the current IP address')
    p.add_argument('zone_id', help='The DNS zone id to update')
    p.add_argument('hostname', help='The DNS name to update')

    return p.parse_args(args)


def _get_local_ipv4():
    conn = http.HTTPConnection('169.254.169.254', 80)
    conn.request('GET', '/latest/meta-data/local-ipv4')
    ipr = conn.getresponse()
    return ipr.read().decode('utf-8')


def _update_dns(ip, zone_id, hostname):
    dns = aws.client('route53')
    dns.change_resource_record_sets(
        HostedZoneId=zone_id,
        ChangeBatch={
            'Comment': 'Update {} record from ASG'.format(args.hostname),
            'Changes': [{
                'Action': 'UPSERT',
                'ResourceRecordSet': {
                    'Name': hostname,
                    'Type': 'A',
                    'TTL': 60,
                    'ResourceRecords': [{
                        'Value': ip
                    }],
                },
            }],
        },
    )


def main(args=None):
    args = _parse_args(args)
    ip = _get_local_ipv4()

    _update_dns(ip, args.zone_id, args.hostname)


if __name__ == '__main__':
    main()