* Building is relatively straightforward on an Ubuntu system. You'll need to install re2 from source, but that's about it.
* No configuration necessary to start playing. lmctfy just straight up mounts cgroups and starts playing in there.
* Containers can be nested which is nice.
* I really couldn't figure out useful values for the container spec. Even the source doesn't seem to have a single reference - it's all dynamically registered by various subsystems in a rather opaque way. I opened a few issues to ask for more details.
* This is a really low-level tool. Other than manipulating cgroups it doesn't seem to do much, which is perfect for my particular use case (docker integration). I couldn't figure out how to set namespaces (including mnt and net namespaces which means all my containers shared the host's filesystem and network interfaces). I don't know if that functionality is already in the code, or has yet to be added.
* Given the fairly small footprint, limited feature set, and clean build experience, this really looks like an interesting option to use as a backend for docker. I like that it carries very little dependencies. Let's see what the verdict is on these missing features.
Are you referring to the container spec in the proto file? https://github.com/google/lmctfy/blob/master/include/lmctfy.... Which attributes are you having trouble setting a useful value for?
And you can approximate mount namespaces with chroots and bind mounts. (In some ways that's better, since it's a bit easier for a process outside the container to interact with the container's filesystem).