Task hooks

Storm provides hooks with which you can insert custom code to run on any number of events within Storm. You create a hook by extending the BaseTaskHook class and overriding the appropriate method for the event you want to catch. There are two ways to register your hook:

1. In the open method of your spout or prepare method of your bolt using the TopologyContext method.
2. Through the Storm configuration using the “topology.auto.task.hooks” config. These hooks are automatically registered in every spout or bolt, and are useful for doing things like integrating with a custom monitoring system.

Worker hooks

Storm also provides worker-level hooks that are called during worker startup, before any bolts or spouts are prepared/opened. You can create such a hook by extending BaseWorkerHook and overriding the methods you want to implement. You can register your hook via TopologyBuilder.addWorkerHook.