Templates/Multi-region API Failover

Multi-region API Failover

InfrastructureAdvancedMission-critical APIs

Active-passive multi-region setup with DNS global load balancer, primary/replica PostgreSQL replication, and automated health-check-driven failover. Use for high-availability APIs with sub-minute RTO.

Recommended for: Teams with strict RTO/RPO targets

6 nodes6 connectionsGeo routingAsync replicationHealth-checked failover

Scope Notes

Intended for Teams with strict RTO/RPO targets at Advanced complexity and Mission-critical APIs scope. Treat the graph as a starting shape rather than a fixed stack: keep the topology and the signals below, then swap providers to match your platform.

Geo routingAsync replicationHealth-checked failover

Review Checklist

0 of 10 reviewed

Use Case

Mission-critical APIs, financial services, healthcare platforms, global SaaS with SLA requirements

Best Fit Scenarios

  • Active-passive multi-region deployments
  • Services with a hard recovery-time objective
  • Teams rehearsing failover before they need it

Stack Breakdown

DNS / GLBAPI (US-East)API (EU-West)DB PrimaryDB ReplicaHealth Checker

Architecture Layers

1Global load balancing
2Regional API clusters
3Database replication
4Health monitoring

Components by Category

infra

DNS / GLBHealth Checker

backend

API (US-East)API (EU-West)

database

DB PrimaryDB Replica

Why This Topology Works

DNS/GLB steers traffic to the healthy region while async replication keeps the secondary warm, and the health checker continuously probes both regions. The replica is read-only until promotion, which is an explicit operator step — this template teaches the boundary between detection and promotion rather than pretending failover is free.

Scaling Notes

Each region scales independently. Replication lag is the real RPO constraint, and the secondary must be able to absorb full write load before promotion is attempted.

Observability

Monitor replication lag, regional latency, health-check success rate and failover event frequency. Synthetic probes from each region verify the routing path, not just the API processes.

Typical Bottlenecks

  • Replication lag defining the achievable RPO
  • Split-brain risk during replica promotion
  • Failover paths that are never rehearsed

Async Flow and Reliability

Read traffic is served from both regions; writes are confined to the primary and replicate asynchronously. Failover detection is automated but promotion and traffic switching are deliberate operator actions.

Upgrade Path

Add a failover orchestrator that freezes writes and promotes the replica, a replication-lag monitor that can abort an unsafe promotion, and point-in-time-recovery backups before claiming a sub-minute RTO.