Evaluation of Linux Container and full virtualization for HPC Applications in PRACE 5IP

Linux Containers with the build-once run-anywhere principle have gained huge attention in the research community where portability and reproducibility are key concerns. Unlike virtual machines (VMs), containers run the underlying host OS kernel. The container filesystem can include all necessary non-default prerequisites to run the container application at unaltered performance. For that reason, containers are popular in HPC for use with parallel/MPI applications. Some use cases include also abstraction layers, e.g. MPI applications require matching of MPI version between the host and the container, and/or GPU applications require the underlying GPU drivers to be installed within the container filesystem. In short, containers can only abstract what is above the OS kernel, not below. Consequently, portability is not completely granted. Here we focus in PRACE-relevant HPC applications, including MPI and GPU applications, evaluated together with other collaborators from Europe and the USA. In addition to security and performance, PRACE virtualisation-service activity is working on solutions for the portability with templates and guidelines for building portable containers. Interesting and complementary to containers are fully-virtualised workloads running as VM jobs. Such solution is useful in cases where specific OS kernel/platform is required. The management of fully-virtualised workloads are also being considered and evaluated. Regarding security and performance, different container platforms (Docker, Singularity, and uDocker) have been evaluated in this white paper carried out under PRACE-5IP virtualisation service.