Cloud Architecture

Local JWT validation is fast until revocation lags bite you. When to introspect at Cognito, use API Gateway JWT authorizers, and add Verified Permissions for fine-grained authz.

Serializable sounds safest until your checkout times out under row locks. This guide maps READ COMMITTED, REPEATABLE READ, and SERIALIZABLE to RDS/Aurora defaults—and when DynamoDB conditional writes are the BASE alternative.

Autovacuum cannot keep up after Black Friday bulk deletes—and your BRIN index is not helping point lookups. Vacuum strategy on Aurora, plus Aurora Limitless and DynamoDB hot key mitigation.

Token buckets allow bursts; leaky buckets smooth traffic—WAF rate rules and API Gateway usage plans implement neither perfectly but both matter for layered defense.

A full TLS handshake on every API call adds RTTs your p99 cannot afford. This guide walks TLS 1.3 1-RTT resumption, ACM cert rotation, and security policies on ALB and CloudFront.

Project Loom virtual threads help I/O-bound Java on ECS—not CPU-bound aggregation. Compare actor models, lock-free queues, and when Lambda concurrency beats pinning threads on EC2.

Control Tower gets you an org; it does not tell you how many OUs you need or which policy type owns VPC public access. Since re:Invent 2024 you have four layers — SCP, RCP, declarative, and tag policies — and RCP coverage grew through Feb 2026 (DynamoDB). A composite 60-account enterprise cut exception SCP attachments from 14 ad-hoc to 3 time-boxed RFCs in two quarters by moving accounts out of "temporary" prod OUs.

On June 10, 2026 AWS GA’d M9g/M9gd on Graviton5 — up to 25% more compute vs M8g, 35% faster for web and ML per AWS. Field guide: M9g vs M9gd, canary checklist, RI traps, and agentic-AI fit.

Your landing zone set up the org, OUs, and baseline SCPs — then most teams stall, duplicating resources per account and wiring brittle cross-account role chains. Since re:Invent 2024 the toolkit changed: RCPs bound what can be done TO a resource (even by external principals), declarative policies enforce EC2/VPC/EBS config state that survives new APIs, and one Route 53 Profile can push DNS to up to 5,000 VPCs. Here is the mechanism-by-job decision matrix and a rollout order that avoids lockouts.

A composite mid-market manufacturer exited a colo of 150 workloads and ~400 TB in 21 months across 8 waves, with 47 minutes of unplanned cutover downtime (industry median per Gartner: ~4 hours per major cutover). The single-wave alternative bid came in at ~$4.8M; the wave-based program ran ~$2.1M. Here is how the wave plan, dependency cutoff, and rollback layer fit together against a hard landlord deadline.

The EU Data Act drops cloud switching and egress charges to zero by January 12, 2027—and AWS already waives data-transfer-out for customers leaving. So why is exit still expensive? Because the real cost is re-platform time (~$113k in our model), not the ~$4,400 egress line. Here is how to make an AWS workload defensibly reversible.

A stack of ALB + EC2 + RDS Multi-AZ + S3 composes to ~99.83% availability—so promising customers 99.9% is a check you cannot cash. This guide does the composition math, converts it to an error budget (99.9% = 43.2 min/month), and shows why AWS service credits never fund your SLA penalties.