LXC

Translation(s): none

Linux Containers (LXC) provide a Free Software virtualization system for computers running GNU/Linux. This is accomplished through kernel level isolation. It allows one to run multiple virtual units simultaneously. Those units, similar to chroots, are sufficiently isolated to guarantee the required security, but utilize available resources efficiently, as they run on the same kernel.

For all related information visit : http://lxc.sourceforge.net/

LXC is available starting with Debian lenny (Kernel 2.6.26), however the LXC userspace tools are not packaged for lenny, so they would have to be built from source. Squeeze will have full support for LXC.

Installation

Install required packages

aptitude install lxc

Install optional packages

aptitude install bridge-utils libvirt-bin debootstrap

Prepare the host

Required: Mount cgroup reboot save (since 595964 /sys/fs/cgroup is prepared to mount cgroup, see also 601757)

Add this line to /etc/fstab

cgroup          /sys/fs/cgroup         cgroup  defaults        0       0

Try to mount it (a reboot solves an eventual "resource busy problem" in any case)

mount -a

Optional: Enable memory cgroup support (534964) (CONFIG_CGROUP_MEM_RES_CTLR) - Since 2.6.39-bpo60-2 for Squeeze the memory cgroup support is built in, so lxc-checkconfig will give you a green result about this point. At the same time, it is deactivated by default. You need to activate memory cgroup support with a kernel parameter. When using grub2, this can be easily done by adding GRUB_CMDLINE_LINUX="cgroup_enable=memory" in /etc/default/grub and running update-grub2. Same for CONFIG_CGROUP_MEM_RES_CTLR_SWAP - see http://lists.debian.org/debian-kernel/2012/01/msg00804.html .

RootFS creation

In therory you may use any tool to create a rootfs (debootstrap, multistrap, rootstock) as long as you are sure, that the result will run inside a container.
For the first time and as an example, use the provided creation script of the lxc package:

lxc-create -n myfirstcontainer -t debian

Setup networked containers

Create a bridge on the host (natted/routed), /SimpleBridge
VLAN + bridge setup description, see /VlanNetworking
Use libvirt package for easy network setup (/LibVirtDefaultNetwork)

Start and stop containers

To start a container and stay attached to the console run:

lxc-start -n myfirstcontainer

To start a container in the background and attached to the console at any time later run:

lxc-start -n myfirstcontainer -d
lxc-console -n myfirstcontainer

To halt a container cleanly by the containers initv-system:

lxc-halt -n myfirstcontainer

To stop a container without proper halt inside the container:

lxc-stop -n myfirstcontainer

References

Known bugs and "got to know issues"

600466 - "Respawning too fast" messages due to missing tty(123) nodes in generated container rootfs (manual workaround: mknod -m 660 dev/tty1 c 5 1)