Seamless and Secure Application Consolidation for Optimizing Instance Deployment in Clouds

摘要

In Infrastructure-as-a-Service clouds, users can reduce costs by scale-in or-down when running applications are under-utilized. Since these optimizations of instance deployment require at least one minimum instance even for running an under-utilized application, cost reduction is limited. For further optimization, multiple applications can be consolidated into one instance. However, applications have to be stopped temporarily at the consolidation time and isolation between applications becomes weaker after the consolidation. To solve these problems, this paper proposes FlexCapsule, which enables seamless and secure application consolidation in existing IaaS clouds. FlexCapsule runs each application in a lightweight virtual machine (VM), called an app VM, using a library operating system. An app VM runs inside an instance using nested virtualization. Using VM migration, FlexCapsule can optimize instance deployment with negligible downtime. Thanks to strong isolation provided by app VMs, it guarantees security between consolidated applications. In addition, FlexCapsule provides multi-process support using app VMs such as process fork and process pools. We have implemented FlexCapsule using Xen and OSv and confirmed its effectiveness.