funcX: Federated Function as a Service for Science

f funcX is a distributed function as a service (FaaS) platform that enables flexible, scalable, and high performance remote function execution. Unlike centralized FaaS systems, f funcX decouples the cloud-hosted management functionality from the edge-hosted execution functionality. f funcX's endpoint software can be deployed, by users or administrators, on arbitrary laptops, clouds, clusters, and supercomputers, in effect turning them into function serving systems. f funcX's cloud-hosted service provides a single location for registering, sharing, and managing both functions and endpoints. It allows for transparent, secure, and reliable function execution across the federated ecosystem of endpoints-enabling users to route functions to endpoints based on specific needs. f funcX uses containers (e.g., Docker, Singularity, and Shifter) to provide common execution environments across endpoints. f funcX implements various container management strategies to execute functions with high performance and efficiency on diverse f funcX endpoints. f funcX also integrates with an in-memory data store and Globus for managing data that may span endpoints. We motivate the need for f funcX, present our prototype design and implementation, and demonstrate, via experiments on two supercomputers, that f funcX can scale to more than 130000 concurrent workers. We show that f funcX's container warming-aware routing algorithm can reduce the completion time for 3,000 functions by up to 61% compared to a randomized algorithm and the in-memory data store can speed up data transfers by up to 3x compared to a shared file system.