Cloudscheduler: a VM provisioning system for a distributed compute cloud

We describe a high-throughput computing system for running jobs on public and private computing clouds using the HTCondor job scheduler and the cloudscheduler VM provisioning service. The distributed cloud computing system is designed to simultaneously use dedicated and opportunistic cloud resources at local and remote locations. It has been used for large scale production particle physics workloads for many years using thousands of cores on three continents. Cloudscheduler has been modernized to take advantage of new software designs, improved operating system capabilities and support packages. The result is a more resilient and scalable system, with expanded capabilities.