多区域AWS API Gateway高可用配置问询（us-east-1/2）

Great question! Let’s break down where you’re at and what’s needed to get automatic failover between your us-east-1 and us-east-2 API Gateway instances.

What You’ve Done Right So Far #

You’ve checked off some critical prerequisites for multi-region HA:

• Deployed your API service in both target regions (us-east-1 and us-east-2)
• Used Regional API Gateway type (not Edge-optimized) — this is perfect because Edge-optimized APIs rely on a single CloudFront distribution, which defeats multi-region failover goals
• Created region-specific ACM certificates for your custom domain — since ACM certificates are region-locked, this is a must to enable HTTPS for each regional API

Does This Setup Meet HA Failover Requirements? #

Short answer: Not yet. Your current setup has two independent regional APIs, but there’s no global traffic router or health check mechanism to automatically shift traffic when the primary (us-east-1) instance fails. Users would still have to manually update DNS or switch endpoints to use the us-east-2 API if the primary goes down.

Missing Steps to Enable Automatic Failover #

To get full automatic HA with traffic routing on failure, you’ll need to add a global DNS layer with health checks using AWS Route 53. Here’s what to do:

1. Set up a Route 53 Hosted Zone (if you don’t already have one for your custom domain)

   • Update your domain registrar’s DNS servers to point to Route 53’s hosted zone servers. This lets Route 53 manage all traffic routing for your domain.

2. Configure Route 53 Failover Routing

   • Create two DNS records for your custom domain:
     • A Primary record pointing to your us-east-1 Regional API Gateway’s custom domain endpoint
     • A Secondary record pointing to your us-east-2 Regional API Gateway’s custom domain endpoint
   • Set the routing policy for both records to Failover. This tells Route 53 to send traffic to the Primary record unless it fails health checks.

3. Add Route 53 Health Checks for the Primary API

   • Create a health check targeting your us-east-1 API’s health endpoint (e.g., /health — make sure this endpoint returns a 200 OK status and doesn’t depend on complex backend logic to avoid false positives)
   • Associate this health check with your Primary Route 53 record. When the health check fails (e.g., API is down or unresponsive), Route 53 will automatically start routing all traffic to the Secondary (us-east-2) record.

4. Validate End-to-End Flow

   • Confirm both regional APIs are accessible via their custom domains
   • Test failover manually: temporarily take down the us-east-1 API (or block the health check endpoint) and verify that traffic shifts to us-east-2 without user intervention
   • Optional: Adjust health check thresholds (e.g., require 3 consecutive failures before switching) to avoid unnecessary failover from transient issues

Bonus Considerations #

• Stateless APIs: Ensure your API is stateless so users don’t lose session data when failover occurs. If state is required, use a global data store like DynamoDB Global Tables.
• Monitoring: Set up CloudWatch alerts for Route 53 health check failures and API Gateway metrics (like 5xx errors) to get notified when failover triggers.
• Latency Optimization: If you want to route traffic to the closest region under normal conditions (instead of only failing over), consider using a Geoproximity or Latency routing policy alongside failover.

内容的提问来源于stack exchange，提问作者Vishnu Ranganathan