We need to upgrade the production Indexer and Matcher (and Notifier) DBs to postgres 15 to support future work. It appears that the most efficient way to do this would be to use RDS blue/green deployments to ensure minimal downtime.

The theory is that we'd have the production instance (blue) and another instance (green) that is being logically replicated to. The green instance is then upgraded (this can take ~24h for larger datasets). Once this is done and the correctness of the green instance has been confirmed, we'd switch the primary over to the green instance and the two instances would switch places.

https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/blue-green-deployments.html

WIP docs for app-interface: https://gitlab.cee.redhat.com/service/app-interface/-/merge_requests/115700