Secure Multi-Tenant Architecture on AWS: Database-Level Isolation and IAM Policies

Designing enterprise-grade SaaS platforms requires making sure tenant data is hermetically isolated from others while maintaining cost-effective infrastructure footprint sharing.

### 1. Tenant Isolation: Silo vs. Pool In a Pool model, tenants share computing resources and databases. To guarantee strict isolation in Pool, we implement PostgreSQL Row-Level Security (RLS) policies, automatically filtering all queries through a secure session context defining the active tenant ID.

### 2. Dynamic IAM Policies using AWS STS Instead of assigning static credentials, application services assume short-lived IAM roles via AWS Security Token Service (STS), generating dynamic scoping policies based on tenant metadata tags at runtime.

### 3. Throttling and Noise-Neighbor Prevention Enforce granular throttling limits on AWS API Gateway per API key/tenant, guaranteeing that usage spikes from a single tenant do not exhaust global database connections or degrade performance for others.