have a problem I was hoping someone could help me with. We have two RDS read slaves that we have our app servers round-robin to for data reads (DNS in Route53).
Well, yesterday those RDSes got restarted by AWS and changed IPs and it all stopped working. We have a CNAME to the master that the app uses for writes, which is more resilient, but you can't round-robin CNAMEs. You also can't elastic-IP a RDS. What is a good solution to using multiple read slaves from an arbitrary app (not changing the app to make it call the API to figure it out) that's resilient to restarts/IP changes?
Have you considered doing weighted round robin? You can configure them with Route 53 and use CNAMEs.
http://docs.aws.amazon.com/Route53/latest/DeveloperGuide/routing-policy.html#routing-policy-weighted