[lxc-users] base container for multiple children on zfs

Volker Cordes mail at vcordes.info
Tue Dec 13 17:51:35 UTC 2016


I would like to set up a hosted web app with lxd. I was thinking of
using a separate container for each user by creating a base container
with the webapp preinstalled, publishing it as an image and create the
user containers using this image. While thinking about this, some
question came into mind:

- Is it correct, that when the base container has to be updated, I still
have to update every user container, because zfs is block based and not
file based? Would it be better to use overlayfs as a backend?

- I would like to have a separate data partition inside each user
container, where user specific data is stored. Is it possible to create
manual file systems inside the lxd zfs pool? Or could it happen that
they get lost (deleted by lxd for example) so that I should use a
different zfs pool for that? How can I mount the filesystem inside the
container - is this supported by the disk device or do I have to mount
them on the host and use a bind mount? This would allow me to update
only the base image, create a new container and just mount the data
partition, so I wouldn't have to update every user container.

- How do I back up the data? Would zrep work? If yes, is it possible to
back up the whole pool or do I have to backup the containers and the
images filesystem separately? For fast recovery it would be nice to just
mirror the whole pool to another server. Or should I use DRBD for that?


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