Revision as of 16:36, November 14, 2014 by Palica (Talk | contribs)

Linux Containers, or LXC, is a Linux feature that allows Linux to run one or more isolated virtual systems (with their own network interfaces, process namespace, user namespace, and power state) using a single Linux kernel on a single server. To learn more take a look at the LXC article.

In this Funtoo (Howto) you will be shown how to create containers, how to start, stop, freeze and unfreeze them and also some more fun parts like snapshoting and clonig. To have all this working you will have to have your lxc store to be on a btrfs system.

Creating containers

Creating containers is quite easy using lxc-templates. They are located in the /usr/share/lxc/templates directory. You can find there many distributions like archlinux, centos, debian, fedora, opensuse, ubuntu, gentoo and some more. There is also an inofficial funtoo template that can be found at https://github.com/golodhrim/lxc-funtoo/blob/master/lxc-funtoo. The script creates funtoo container, however I was not able to use it with lxc-create script from the lxc utils.

So how do you create other containers? I am going to use a debian container for this purpose. You will have to emerge debootstrap.

# emerge -av debootstrap

 * IMPORTANT: 8 news items need reading for repository 'gentoo'.
 * Use eselect news to read news items.

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild  N     ] dev-perl/TimeDate-2.300.0  31 kB
[ebuild  N     ] app-arch/dpkg-1.17.10  USE="bzip2 lzma nls unicode update-alternatives zlib -dselect {-test}" 4,100 kB
[ebuild  N     ] dev-util/debootstrap-1.0.59  96 kB

Total: 3 packages (3 new), Size of downloads: 4,226 kB

Would you like to merge these packages? [Yes/No]

After this you can create your debian container using:

# lxc-create -n vm1 -t debian
debootstrap is /usr/bin/debootstrap
Checking cache download in /var/cache/lxc/debian/rootfs-wheezy-armhf ... 
Copying rootfs to /var/lib/lxc/vm1/rootfs...Generating locales (this might take a while)...
  en_US.UTF-8... done
Generation complete.
update-rc.d: using dependency based boot sequencing
update-rc.d: using dependency based boot sequencing
update-rc.d: using dependency based boot sequencing
update-rc.d: using dependency based boot sequencing
Creating SSH2 RSA key; this may take some time ...
Creating SSH2 DSA key; this may take some time ...
Creating SSH2 ECDSA key; this may take some time ...
invoke-rc.d: policy-rc.d denied execution of restart.
Timezone in container is not configured. Adjust it manually.
Root password is 'root', please change !

Now you are ready to do all the fun stuff with your LXCs.

Starting/stoping containers

To start a previously created container use the lxc utils:

# lxc-start -n vm1 -d
# lxc-info -n vm1
Name:           vm1
State:          RUNNING
PID:            29742
CPU use:        2.92 seconds
BlkIO use:      260.00 KiB
Memory use:     2.99 MiB
KMem use:       0 bytes
Link:           vethTN4NGU
 TX bytes:      2.33 KiB
 RX bytes:      39.54 KiB
 Total bytes:   41.87 KiB
# lxc-attach -n vm1
# root@vm1:~#
# root@vm1:~# exit
# lxc-stop -n vm1
Name:           vm1
State:          STOPPED