Building a Custom Metrics Exporter for Kubernetes

A custom metrics exporter for Kubernetes bridges the gap between built-in metrics and real-world scaling signals. It exposes application state as text on a /metrics endpoint, which Prometheus scrapes and stores for queries, alerts, and autoscaling rules. To write one, decide what signal to measure, choose a Prometheus data type (counter, gauge, histogram), and follow a naming convention. The Go Prometheus client is a common choice for implementation.