Never hardcode your database passwords. AWS Secrets Manager provides a secure warehouse for your most sensitive credentials.
Instead of reading from a local `.env` or `appsettings.json`, your .NET configuration provider can call the Secrets Manager API at startup. This ensures that even if a developer gets access to your source code, they won't have the production passwords.
The killer feature. Secrets Manager can automatically change your RDS password every 30 days and update itself. Your .NET app just keeps fetching the 'Latest' version, and the transition is seamless. This is a massive win for compliance (SOC2/PCI-DSS).
Q: "Should I use Secrets Manager or Parameter Store?"
Architect Answer: "Use **Parameter Store (SSM)** for non-sensitive config (like API URLs or feature toggles) because it's mostly free. Use **Secrets Manager** for actual passwords because it supports **Automatic Rotation** and is more specialized for high-security credentials."