API Gateway Monitoring in Practice: Metrics Collection and Alert Design from Kong to APISIX
Overview At 2 AM, the payment system alerts exploded. After digging through logs for ages, we discovered the downstream services weren’t down — the API gateway’s connection pool was exhausted. Requests piled up at the gateway layer and never made it through. But our monitoring dashboard only showed CPU and memory curves, completely blind to gateway-level latency, connection counts, and error rates. This isn’t an isolated case. I’ve seen too many teams treat API gateways as “fancy Nginx” and only monitor nginx_active_connections, only digging into logs when things break....