“High-Performance Computing in the Cloud? That does not really work for real number crunching.” That was the general opinion for a long time in the HPC community. Then Docker came along. Its containers solved some of the problems – especially replacing heavy Virtual Machines with light weight containers, but it still had a strong feeling of “work in progress”. During the Computing Insight UK 2015, Wolfgang Gentzsch – from UberCloud – and Hans Then – from ClusterVision, jointly presented a complete HPC Cloud stack based on Docker. UberCloud provides HPC -optimised application containers based on Docker. ClusterVision’s Trinity platform allows operating an HPC cluster from a regular Cloud dashboard. Together, they showed that Trinity is capable of managing UberCloud’s highly optimised application containers. Today you can operate a cluster as a cloud without giving up on performance. Hans Then and Wolfgang Gentzsch explained to us how they converged over 2015 with the initial concepts and how they demonstrated that building an HPC environment in this manner actually works.