In early systems architecture, security was modeled like a medieval castle: build a thick perimeter wall (firewall, VPN), and trust everything inside the internal network. In modern cloud and microservice environments, the perimeter model is dead. An attacker breaching a single test pod or developer laptop gains unfettered access to all internal databases and services.
Modern distributed systems enforce Zero Trust: assume the network is hostile, authenticate every single RPC cryptographically via Mutual TLS (mTLS) and SPIFFE/SPIRE, and strictly isolate multi-tenant workloads.
This module deconstructs distributed security and multi-tenancy:
- Workload Cryptographic Identity: How service meshes use SPIFFE IDs and ephemeral X.509 certificates to verify service-to-service communication.
- Multi-Tenant Isolation Models: The trade-offs of shared-database vs. isolated-database models across cost, compliance (SOC2/HIPAA), and noisy-neighbor risk.
- Stateless Tokens vs. Revocation: Fast local JWT validation using public keys vs. distributed blacklists for instantaneous token revocation.
- Fair Queuing & Tenant Quotas: Preventing one rogue tenant from consuming 100% of database connection pools and background worker queues.