Here's some simple practical tips you can use to prevent this and other Oh Shit Moments(tm):
- Unless you have full time DBAs, do use a managed db like RDS, so you don't have to worry about whether you've setup the backups correctly. Saving a few bucks here is incredibly shortsighted, your database is probably the most valuable asset you have. RDS allows point-in-time restore of your DB instance to any second during your retention period, up to the last five minutes. That will make you sleep better at night.
- Separate your prod and dev AWS accounts entirely. It doesn't cost you anything (in fact, you get 2x the AWS free tier benefit, score!), and it's also a big help in monitoring your cloud spend later on. Everyone, including the junior dev, should have full access to the dev environment. Fewer people should have prod access (everything devs may need for day-to-day work like logs should be streamed to some other accessible system, like Splunk or Loggly). Assuming a prod context should always require an additional step for those with access, and the separate AWS account provides that bit of friction.
- The prod RDS security group should only allow traffic from white listed security groups also in the prod environment. For those really requiring a connection to the prod DB, it is therefore always a two-step process: local -> prod host -> prod db. But carefully consider why are you even doing this in the first place? If you find yourself doing this often, perhaps you need more internal tooling (like an admin interface, again behind a whitelisting SG).
- Use a discovery service for the prod resources. One of the simplest methods is just to setup a Route 53 Private Hosted Zone in the prod account, which takes about a minute. Create an alias entry like "db.prod.private" pointing to the RDS and use that in all configurations. Except for the Route 53 record, the actual address for your DB should not appear anywhere. Even if everything else goes sideways, you've assumed a prod context locally by mistake and you run some tool that is pointed to the prod config, the address doesn't resolve in a local context.