Custom service discovery with etcd

This article details how to implement custom service discovery in Prometheus using etcd, a distributed key-value store. It describes building a utility program that watches for changes in etcd (specifically under a `/services` path) and dynamically generates a JSON file of target groups that Prometheus can then use for service discovery. By leveraging etcd's watch functionality, the program efficiently updates Prometheus with new or removed services and instances, enabling automated monitoring without manual configuration.