Define a WDL workflow to subsample jointly called VCF files. This workflow accepts an input VCF referenced with either a DRS URI or Google Storage URL, and an array of sample IDs. Output is a Google Storage URL.
In order to keep hard disk requirements small and improve performance, input/output objects are streamed directly from cloud storage using FIFO queus (named pipes).
An appropriate workflow configuration is ~16GB RAM, ~8 CPUs, and standard storage.