After moving my personal domains over to Amazon and Route53, I wanted to do dynamic DNS updates for a few names in my domains. Unfortunately, Amazon doesn't support TSIG, and doesn't have a very simple API for trivial Route53 updates, so I whipped up a small tool with Python and AWS Lambda.
This dynamic DNS system requires an AWS Lambda as well as an API Gateway
configured to serve the Lambda. The ddupdate program will communicate
to the API Gateway, and transmit several options about the pending update.
The list of options includes a security token - essentially, a shared secret
for updating a particular hostname/zone ID combination.