1. A method, comprising: determining that use of a system resource of a first host system satisfies a migration condition, wherein the first host system executes a plurality of virtual machines in a cloud computing environment; identifying a first virtual machine, of the plurality of virtual machines, for migration based on a first migration policy, of a plurality of migration policies, wherein the plurality of migration policies specify a respective set of rules for identifying virtual machines for migration; and migrating the first virtual machine to a second host system in the cloud computing environment to reduce the use of the system resource on the first host system.