Updates the IP address of a Route 53 record to the current host's WAN IP. If you use Route 53 and can run this script regularly on a host behind a dynamic IP, you can stop using a third-party dynamic DNS service.

Unpack this script somewhere and make sure the python packages boto and py3dns are available to it.

• Python 3
• Python packages boto and py3dns
• Values for AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY
• A Route 53 hosted zone with an A-record subdomain

If you've been pointing a subdomain at a dynamic DNS subdomain in the past (e.g. subdomain.example.org -> subdomain.dyndns.com -> 1.2.3.4), then you'll be using a CNAME record. Rome 53 expects an A record, and to avoid disaster, will not modify records of other types.

To make the change, you should first manually update the subdomain to use an A record.

The easiest way to provide credentials for AWS is to set the AWS_ACCESS_KEY_ID and AWS_SECRET_ACCESS_KEY environment variables before running Rome 53.

$ python rome53.py subdomain.example.org
Looking for subdomain.example.org. in your Route 53
Updating DNS A record to 1.2.3.5 (was 1.2.3.4)
DNS update request succeeded.
You can ^C now, or await confirmation of the propagation.
Waiting for DNS update to sync... (0s)
Waiting for DNS update to sync... (5s)
subdomain.example.org 1.2.3.5

$ python rome53.py subdomain.example.org
Looking for subdomain.example.org. in your Route 53
Current WAN IP matches DNS record (1.2.3.5). Doing nothing.

Rome 53 does this for you using myip.opendns.com. You can check which IP this will currently result in using dig:

$ dig myip.opendns.com @resolver1.opendns.com +short
1.2.3.4

Use the --ip option. This is handy for undoing a mistake where, for example, maybe you accidentally provided the wrong subdomain to Rome 53, and now your payment gateway resolves to a computer in your kitchen.

$ python rome53.py gateway.example.org
Looking for gateway.example.org. in your Route 53
Updating DNS A record to 100.1.1.1 (was 50.1.1.1)
DNS update request succeeded.
# woops!

$ python rome53.py gateway.example.org --ip 50.1.1.1  # from "was..." above
Looking for gateway.example.org. in your Route 53
Updating DNS A record to 50.1.1.1 (was 100.1.1.1)
DNS update request succeeded.

For scripting, use the --quiet option to reduce chattiness. When quiet, Rome 53 will produce no output unless an IP update occurs. If so, one line is output: <domain>\t<ipaddr>. This is suitable for scripting or appending to a log file.

Rome 53 does not check if it's already running. The await-sync stage can take more than one minute, meaning an every-minute cron job may cause two Rome 53s to run at once. This is probably harmless, but you may want to use */5 anyway.