Originally published on Entropic Drift
Most Rust services start clean.
There is a handler, a database call, a few validation checks, a small amount of business logic, and a response. The code is direct. You can read it top to bottom.
Then the service grows.
Validation gets more detailed. A second database lookup appears. Password hashing moves into the flow. You add a uniqueness check. There is a welcome email, a retry policy for the email provider, a metric, and a bit of context on errors so production logs are useful.
