The main interface between configuration and statistics data from Unikraft and applications is ukstore. It is based on ProcFS and offers easy “folder/data” access. This solves the problem of searching through headers to find functions that offer information. The main advantage of ukstore is that all of its setup is done at build-time so there is no impact on the boot-time. Furthermore, it has flexibility, by offering the possibility to create both static entries (created at build-time) and dynamic entries (created at run-time).

Metrics inside Unikraft are provided by the libraries that generate them. As such, every library can contain functions that offer usage data. At the moment, work was done to offer metrics related to memory, networking, and thread-locking, with metrics related to file systems and the CPU underway. The end goal is to cover as much of the known metrics from Linux, offered through ProcFS, and expose them through ukstore.

Porting a Prometheus exporter came with the challenge of finding one with the least amount of dependencies, whilst still retaining the usual format. We chose an exporter and adapted it through patches to successfully interact with Unikraft and exposed available performance metrics through it. With all the above puzzle pieces put together, Unikraft instances can be monitored reliably with a minimal impact on the performance of the instances themselves.