Get SWAP information for your LXD containers

If you use LXD and you have SWAP enabled on your host machine you may want to know the SWAP usage of some containers.

To do that, you must first enable the SWAP accounting in Linux, that can be done by adding a kernel parameter at boot time. If you use GRUB, you just need to edit the line GRUB_CMDLINE_LINUX_DEFAULT= and add swapaccount=1, then update-grub && reboot.

You can then have some stats with lxc info:

$ lxc info toots
  Memory usage:
    Memory (current): 860.96MiB
    Memory (peak): 1.64GiB
    Swap (current): 563.36MiB
    Swap (peak): 87.00MiB

Looks like it is a little buggy though, peak value behind under current value.