Saturday, January 30, 2016

unikernels & production

A recent blog called into question the fitness of unikernels for production. The title was a bit misleading as there are several unikernel  systems out there. some of which are actually in production - one of our faves is the NEC/Bucharest Uni work on ClickOS, for example, which is used for NFV on switches and is clearly a class act.

However, I think the article is also missing some of the main motives behind MirageOS (see e.g. Jitsu or the asplos paper) which was based in experiences with managing a lot of Xen based cloud systems - sure, Unikernels are specialised, and don't possess a lot of the micro-management/debugging tools (yet, although a lot are on the way) that you have for kernel debugging or system tracing of linux etc etc. But that's because OCaml real world experience in production was that you have faster system creation, and way faster debugging times. However, that's still not the whole story- the story is that the whole toolchain for managing source, building a unikernel, deploying it and tracing it is much more homogeneous - so a whole system of unikernels is easier to manage (as per previous experience).

Crucially, we are also able to verify some components of the MirageOS (e.g. Peter Sewell's group in cambridge did this (for some definition of "this") a while back for the TCP/IP stack, plus confidence about David and Hannes TLS implementation can be quite a bit higher than the "industry standard" that had 65 vulnerabilities in one year alone.

But all this is missing yet another key factor - unikernels don't replace xen/linux or containers - they play side-by-side with them, so you can have flexibility and familiarity, while affording better protection - that's in the Jitsu paper btw, and I thought was fairly clear.

Sure there's some way to go - there always is -there was when Xen first shipped too. But the computer science behind this is not that bleeding edge (nor were VMs back in Xensource's day either:-), but the science is 15 years further on, and we should all benefit from that, in my opinion. Indeed, it took a day to add profiling

xkcd has us in there thrice

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