1. A computer-readable storage medium storing computer-readable program code which, when executed on a processor, performs an operation, the operation comprising: launching a first plurality of virtual machines, wherein each virtual machine provides a virtualized computing platform hosting an operating system; assigning the first plurality of virtual machines to a pool of virtual machines available to a plurality of scale groups, each of the scale groups is associated with a respective computing service provided by a respective second plurality of operating virtual machines assigned to each of the scale groups; detecting a scaling event corresponding to a first group of the plurality of scale groups; selecting, in response to detecting the scaling event, one of the first plurality of virtual machines assigned to the pool; mounting a persistent storage volume associated with the first group to the selected virtual machine; invoking a script associated with the computing service associated with the first group in response to mounting the persistent storage volume which stores the script, wherein the script modifies the selected virtual machine according to a predefined configuration for the first group to provide the computing service; assigning the selected virtual machine to the first group; and in response to detecting a scaling event corresponding to a second group of the plurality of scale groups: determining that a priority assigned to the second group does not satisfy a priority requirement corresponding to the pool of virtual machines, wherein the priority of the second group is based on at least one of a subscription fee, an importance of tasks performed by the second group, and a customer importance, and launching a new virtual machine to be assigned to the second group instead of using the pool of virtual machines.