# Pebble **Pebble** is a lightweight, API-driven process supervisor. When Juju provisions resources on a Kubernetes cloud, Pebble is automatically injected into each container, where it acts like an `init` system, and charm interacts with its workload through the workload container’s Pebble. See more: [Pebble documentation](https://canonical-pebble.readthedocs-hosted.com/en/latest/), [Debugging tips](https://documentation.ubuntu.com/juju/3.6/howto/manage-charms.md#debug-a-k8s-charm-with-a-workload) ## Pebble notices In Pebble, a **notice** is an aggregated event to record when custom events happen in the workload container or in Pebble itself. See more: [Pebble | Notices](https://canonical-pebble.readthedocs-hosted.com/en/latest/reference/notices/#) Pebble notices are supported in Juju starting with version 3.4. Juju polls each workload container’s Pebble server for new notices, and fires an event to the charm when a notice first occurs as well as each time it repeats. Each notice has a *type* and *key*, the combination of which uniquely identifies it. A notice’s count of occurrences is incremented every time a notice with that type and key combination occurs. Currently, the only notice type is “custom”. These are custom notices recorded by a user of Pebble; in future, other notice types may be recorded by Pebble itself. When a custom notice occurs, Juju fires a [`PebbleCustomNoticeEvent`](https://ops.readthedocs.io/en/latest/reference/ops.html#ops.PebbleCustomNoticeEvent) event whose [`workload`](https://ops.readthedocs.io/en/latest/reference/ops.html#ops.WorkloadEvent.workload) attribute is set to the relevant container. Custom notices allow the workload to wake up the charm when something interesting happens with the workload, for example, when a PostgreSQL backup process finishes, or some kind of alert occurs.