We often get questions such as:
- why don't you use virualisation?
- why don't you OpenStack?
- why don't you use Docker?
- etc.
We usually answer: because they don't work according to industrial grade standards, even now, and because they did not exist in 2008.
The meaning of "does not work" is a bit different for Nexedi and for most open source developers. In Nexedi, we want systems that "work always in the same way and for a very long time", rather than systems that "work sometimes" and are easy to install with a beautiful web site. We want this kind of predictability for everything (build, ordering, etc.). We care more about improving our software than community or documentation. If a solution works but is rejected by most community, we ignore community because we have to serve our customers first (our business model is based on customers, not on venture capital).
The article "Are Linux containers stable enough for production and why Nexedi uses SlapOS nano-containers instead ?" (https://www.nexedi.com/NXD-Blog.Docker.SlapOS.Nano.Container.Elbe) explains for example why we do not use Docker or LXC containers and why we do not plan to use them for ourselves. Until recently, it was very difficult to find anyone who would agree with us (just like OpenStack 10 years ago). But more and more people now understand the problems of binary portability with Linux kernel and its consequence on Docker/LXC containers.
So, we might use "kernel namespaces" with SlapOS.
SlapOS could easily support docker/LXC type containers; we actually already implemented it. But those docker/LXC containers will only work if some strict conditions are met: host OS/Kernel and guest OS/Kernel should be same for example. Sadly most developers do not understand those conditions and do not respect them. It is thus difficult to provide something that works according to our standards.