Serverless Monitoring Challenges
AWS Lambda's pay-per-invocation model is cost-effective, but its ephemeral nature makes monitoring harder. Functions cold-start, timeout, throttle, and fail in ways traditional monitoring doesn't catch. External HTTP monitoring from multiple regions is the most reliable way to verify your serverless APIs work end-to-end.
Cold Start Impact on User Experience
Lambda cold starts add 100ms to 10+ seconds of latency depending on runtime, package size, and VPC configuration. Monitor your API Gateway endpoints with response-time thresholds to catch cold-start regressions after deployments.
Provisioned Concurrency Monitoring
If you use provisioned concurrency to mitigate cold starts, monitor that it's working. A misconfigured provisioned concurrency setting can silently revert to on-demand, reintroducing cold starts.
VPC Cold Starts
Lambda functions in VPCs experience significantly longer cold starts due to ENI attachment. Monitor VPC-attached functions separately with higher timeout thresholds.
Monitoring a Commercial SaaS?
FourSight includes 25 commercial-safe monitors with multi-region validation.
Start Monitoring FreeThrottling Detection
Lambda has concurrency limits per region (default 1000). When you hit limits, API Gateway returns 429 errors. Monitor for these with HTTP status code checks—throttling often happens during traffic spikes when you need reliability most.
API Gateway Health
API Gateway can fail independently of your Lambda functions. Monitor your API's base URL and critical routes separately. Check for proper CORS headers if your frontend is a SPA—missing CORS headers produce confusing client-side errors.
Multi-Region Failover Verification
If you run a multi-region Lambda setup with Route 53 failover, use FourSight's multi-region monitoring to verify that failover actually works. Test from regions closest to each deployment to ensure DNS routing is correct.