The problem I'm having is that LXC and Docker require something to control memory usage. In Arch at least, this is controlled via the cgroup file system. However, there is no cgroup in the fstab on Linode, presumably because the partitioning scheme wasn't set up that way. All I want is to use LXC/Docker on Linode running Arch. Can anyone tell me how?

Docker runs on Arch out-of-the-box on Linodes. It does not require the memory cgroup, and works totally fine except for the obvious inability to limit a container's RAM usage. We did not enable the memory cgroup because it has a noticeable performance impact, and thus we chose not to impact performance for all users so that Docker users could have an optional feature.

If you'd like to use the memory controlling feature of Docker, you'd need to use a custom kernel:

https://library.linode.com/custom-instances

With regard to cgroups themselves, they aren't mounted in /etc/fstab; you may want to check the output of 'mount'.

- Les

So Les,
You're saying I should really have any issues using docker out of the box? I know that cgroup has to be mounted per the Arch Wiki. So... I was wondering if I'd have to create a partition for it or what. I don't really want to roll a custom Kernel. What difficulties if any will I encounter by not having memory management for Docker?

Like, what if I want to run 3 websites on my Linode, all in separate Linux containers? Will I be good?

The only problem I see is... if one site is getting a ton of traffic, the others may suffer because the site getting a ton of traffic has no caps set on it's RAM usage. In fact, it will eat up the entire bank if it needs to. That's what you're saying the only problem is?

The cgroups aren't configured via /etc/fstab and they don't show up in df; they show up in mount. There's no partitioning to be done.

If you don't have the memory cgroup, the only affect it will have on your Docker usage is that you can't limit a container's RAM usage via cgroups. You're still able to use whatever options the daemon itself provides for limiting RAM usage.

- Les