Optimization is one of the key concerns for any cloud service provider. A cloud service provider would want to optimize the costs of the data center and increase the operational efficiency. Watcher is a resource optimization service of OpenStack that helps in achieving the optimization goals.

Watcher provides an optimization loop that comprises measuring metrics, processing events, profiling, an optimization process, and a process to apply the action plan. This framework can help realize goals, such as reducing operational costs, increasing system performance using techniques such as VM migration, and increasing energy efficiency. 

Watcher supports a pluggable architecture. This means that users can develop their own optimization algorithm using their data metrics and profilers. These can then be inserted into the Watcher framework.