RECap: Run-Escape Capsule for On-demand Managed Service Delivery in the Cloud

Application runtimes are undergoing a fundamental transformation in the cloud, from general-purpose op- erating systems (OSes) in virtual machines (VMs) to lightweight, minimal OSes in microcontainers. On one hand, such transformation is helping reduce application footprint in the cloud to increase agility, density and to minimize attack surface. On the other hand it makes it challenging to implement system and application man- agement tasks. Inspired from the on-demand Function as a Service (FaaS) model in serverless computing, in RECap we are designing a cloud-native solution to deliver core systems and application management tasks through specially-managed Capsule containers. Capsule containers are dynamically attached to the running containers for the duration of their implemented function and are safely removed from application context afterwards. More generally, RECap framework allows us to design disaggregated on-demand managed service delivery for containers in the cloud. In this paper, we describe the motivation and the emerging opportunity for RECap in the cloud. We discuss its core design principles, performance, security and manageability trade-offs. We present current design of RECap for the Kubernetes platform.