Towards Making Unikernels Rejuvenatable

Software rejuvenation is a simple but powerful method for improving the availability of computer systems. Software rejuvenation faces a challenge to apply itself to a new type of application, the Unikernel which is a library OS where OS functions are linked to the target applications like libraries. Since the unikernel layer is tightly coupled to applications, rebooting the unikernel layers involves the applications' reboots, eliminating and reconstructing memory contents unrelated to the unikernels. This paper presents VampOS that allows us to rejuve-nate the only unikernellayer. VampOS performs component-level rejuvenation of the unikernel by logging interactions between the components and replaying them to restarted components while simultaneously keeping the linked applications running. We implemented a prototype of VampOS, not well-optimized, on Unikraft 0.8.0 and the experimental results show that its runtime overhead is up to 13.6x and the VampOS-linked SQLite mitigates the effects of the intentionally injected memory leak bugs without any downtime. This paper also describes the next directions for efficient rejuvenation of the unikernel-linked applications.