osv VS linuxkit

I've been looking at a few.

https://github.com/cloudius-systems/osv

https://ops.city/ (also nanovms) - this is one that I actually got working to at least demo state

I have also found OSv to be interesting.

https://osv.io/

Wow, just now seeing this topic. I work for a cloud company hosted in AWS. We started out, Netflix/Spotify style microservices. We were all on ec2 images generate by packer (and later with AWS Image Factory). When Docker hit, we kicked the tires but never did anything with it beyond using it for running unit tests, and later, infrastructure tests. 5 years ago, during a hackathon, our little group began experimenting with Unikernels, or library operating systems. Interestingly enough, these Unikernels were all stripped down BSD kernels. OSv is FreeBSD based, and Rumprun is NetBSD based. Services running in EC2 on Unikernels would spin up and start sending and receiving traffic before the AWS EC2 healthchecks completed. They are blazing fast! Only problem in 2017, was the tooling. It would have taken too much effort to use Unikernals with our infrastructure. As soon as they start making Unikernels that can run Java bytecode like native code, the fate of containerization will be sealed, IMO. We could get basic JVM webservers running on OSv, but not Cassandra, not Kafka, not yet. OSv now runs on Firecracker, but I have not tried it out, yet. Some links if you are interested: OSv: https://osv.io Rumprun: https://github.com/rumpkernel/rumprun We used this tooling during the Hackathon, but doesn't look like it has been touched in 3 years: https://github.com/solo-io/unik Unikraft Unikernel Dev kit: https://unikraft.org/ And don't forget Firecracker running in Kubernetes https://www.weave.works/oss/firekube/ And of course, being a FreeBSD subreddit, let's not forget FreeBSD on Firecracker https://www.daemonology.net/blog/2022-10-18-FreeBSD-Firecracker.html

Whats the difference to OSv?

https://github.com/cloudius-systems/osv

OSv Unikernel — Optimizing Guest OS to Run Stateless and Serverless Apps in the Cloud — Waldek Kozaczuk [OSv Committer] Unikernels have been demonstrated to deliver excellent performance in terms of throughput and latency, while providing high isolation. However they have also been shown to underperform in some types of workloads when compared to a generic OS like Linux. In this presentation, we demonstrate that certain types of workloads - web servers, microservices, and other stateless and/or serverless apps - can greatly benefit from OSv optimized networking stack and other features. We describe number of experiments where OSv outperforms Linux guest: most notably we note 1.6 throughput (req/s) and 0.6 latency improvement (at p99 percentile) when running nginx and 1.7 throughput (req/s) and 0.6 latency improvement (at p99 percentile) when running simple microservice implemented in Golang. We also show that OSv' small kernel, low boot time and memory consumption allow for very high density when running server-less workloads. The experiment described in this presentation shows we can boot 1,800 OSv microVMs per second on AWS c5n.metal machine with 72 CPUs (25 boots/sec on single CPU) with guest boot time recorded as low as 8.98ms at p50 and 31.49ms at p99 percentile respectively. Lastly we also demonstrate how to automate the build process of the OSv kernel tailored exactly to the specific app and/or VMM so that only the code and symbols needed are part of the kernel and nothing more. OSv is an open source project and can be found at https://github.com/cloudius-systems/osv.

I guess you could have a JVM like that, but not OpenJDK. There is, however, a unikernel that supports running itself and OpenJDK in the same process: http://osv.io/

> Oracle used to offer an installation mode like this

Oracle, and BEA before them, used to offer a JVM which ran on top of a thin custom OS designed only to host the JVM, you could call it a "unikernel". Product was called JRockit Virtual Edition (JRVE), WebLogic Server Virtual Edition (WLS-VE, when used to run WebLogic), earlier BEA called it LiquidVM. The internal name for that thin custom OS was in fact "Bare Metal". Similar in concept to https://github.com/cloudius-systems/osv but completely different implementation

I think one thing which caused a problem for it, is a lot of customers want to deploy various management tools to their VMs (security auditing software, performance monitoring software, etc) and when your VM runs a custom OS that becomes very difficult or impossible. So adopting this product could lead to the pain of having to ask for exceptions to policies requiring those tools and then defending the decision to adopt it against those who use those policies to argue against it. I think this is part of why the product was discontinued.

Nowadays, Oracle offers "bare metal servers" [1] – which are just hypervisor-less servers, same as other cloud vendors do. Or similarly, "Oracle Database Appliance Bare Metal System" [2] – which just means not installing a hypervisor on your Oracle Database Appliance.

So Oracle seems to have a history of using the phrase "bare metal" in both the senses being discussed here.

[1] https://www.oracle.com/cloud/compute/bare-metal.html

[2] https://docs.oracle.com/en/engineered-systems/oracle-databas...

Another project that aims to deliver this is Linuxkit (https://github.com/linuxkit/linuxkit). All the components they ship are written in memory safe languages (usually Go) and run as containers under containerd. You can build a custom image very easily, fully defined as a YAML file.

docker-the-company maintained https://github.com/linuxkit/linuxkit when I worked there. I have no idea who maintains it now, but it looks like it is still active (presumably still docker-the-company, since their adopters list [1] lists docker desktop).

[1]: https://github.com/linuxkit/linuxkit/blob/master/ADOPTERS.md

LF-Edge EVE project leverages Linuxkit to create custom OSs for Edge Devices which in turn leverages Containers as Lego Blocks

LinuxKit - Docker

Behind the scenes Docker Desktop for Mac spawns a linuxkit VM with a bit of extra stuff like NFS to enable mounting Mac paths into containers. In the Docker Desktop settings you'll find the current resource assignment for that VM. That is pretty much reserved for docker so that it does not have to compete with MacOS processes for available resources.

That said... you might want to check out linuxkit

The definition of what a unikernel is needs to be narrowed down, a lot of these projects in the space (not all the ones listed above) have material differences that are not clear:

- some run only one language

- some require recompilation

- some essentially swap out libraries, others do something closer to dropping your already mostly static binary in a minimal disk image

- some build pid1 processes, others VMs images

Anyway, here are some additional entries in the space:

- https://ssrg-vt.github.io/hermitux/

- https://github.com/linuxkit/linuxkit (more embedded/minimal VM than unikernel)

- https://nabla-containers.github.io/ (runs on Solo5)

I am going through using Linuxkit to build AMIs for cloud providers now. I wouldn’t necessarily class linuxkit as a universal project because it doesn’t have the hallmark blurring of user and kernel space or kernel-as-a-library but you can customize the kernel so it’s an adjacent idea, and I think it’s the one most likely to be in actual use at non-hyperscalers.

I believe there is growing interest in providing leaner, "trimmed" runtimes for services deployed to the cloud. Today, this is seen largely by specializing the Linux kernel for, for example, container services[0] or in general[1], as much as that is possible (the paper above covers this problem in greater detail). But, Unikernels in themselves are not yet widely adopted. This is the space Unikraft is aiming to enter, providing the ultimate level of specialization for a target application.

It's clear that bigger players, such as Red Hat[2] are interested in the topic of unikernels, and that cloud providers are preparing for this future too [3].

[0]: https://github.com/linuxkit/linuxkit