Prometheus targets are configured at the server either directly in the config or via a service discovery plugin. Prometheus then pulls metrics from these targets at regular intervals. Unless Prometheus has been configuration with a service discovery method each time a new target is added or modified a change must be made in the server configuration.

This service provides a simple API that can run alongside Prometheus allowing adding, updating and deleting of targets via a REST API and without reloading the Prometheus configuration.

The Prometheus Registration service can be installed via Juju as part of the Prometheus charm, https://jujucharms.com/prometheus

Then as new units are added they will be automatically registered with Prometheus if running a charm setup with the promreg-client-layer, https://code.launchpad.net/~timkuhlman/prometheus-registration/+git/layer-promreg-client, such as the telegraf charm, https://jujucharms.com/u/telegraf-charmers/telegraf/1.