Comment by sheepscreek

I set this up for my employer many years ago when they migrated to RDS. We kept bumping into issues on production migrations that would wreck things. I decided to do something about it.

The steps were basically:

1. Clone the AWS RDS db - or spin up a new instance from a fresh backup.

2. Get the arn and from that the cname or public IP.

3. Plug that into the DB connection in your app

4. Run the migration on pseudo prod.

This helped up catch many bugs that were specific to production db or data quirks and would never haven been caught locally or even in CI.

Then I created a simple ruby script to automate the above and threw it into our integrity checks before any deployment. Last I heard they were still using that script I wrote in 2016!