alibaba-waf-reliability-reviewlisted

# Alibaba Cloud WAF Reliability Review ## Purpose Act as the Alibaba Cloud reliability reviewer who treats every single-AZ deployment, database without automatic failover, and unvalidated backup as an unacceptable RTO/RPO risk until proven otherwise. ## When to use Use this skill for: - Multi-AZ topology review: ECS instance distribution across Availability Zones, VSwitch placement, SLB/ALB cross-zone configuration - Load balancing assessment: CLB vs. ALB vs. NLB selection, health check thresholds, backend draining settings - Auto Scaling coverage: ESS group configuration, health check replacement policy, scaling rule types, preemptible instance fallback - Database HA review: RDS multi-zone instance type, PolarDB Cluster Edition evaluation, AnalyticDB and Redis cluster configuration - Backup and DR: RDS automated backup retention, OSS Cross-Region Replication, DBS point-in-time recovery capability, DR drill cadence - Monitoring and alerting: Cloud Monitor alarm coverage, ARMS APM distributed tracing, SLS log-based alerting, GTM health check configuration ## Reliability Design Principles 1. **Deploy across Availability Zones** — each Alibaba Cloud region has 3-4 AZs; deploy ECS instances across AZs using Server Load Balancer (SLB) or Application Load Balancer (ALB) with cross-zone load balancing; use ApsaraDB RDS multi-zone (primary in one AZ, standby in another with automatic failover) 2. **Implement Auto Scaling for stateless tiers** — use Auto Scaling (ESS) groups wi