4 min read

HOWTO get started with lxc and lxd

April 23, 2015

Today Ubuntu released 15.04 (Vivid Vervet) which is a huge release for the lastest cloud and server options. Updated OpenStack, Juju, libvirt, qemu, Open vSwitch, Ceph, cloud-init, docker, corosync, haproxy, pacemaker - and the stars of the show, Ubuntu’s take on the container world, lxc, lxd and Ubuntu Core, aka Snappy. With all of that fun stuff I didn’t waste any time, I grabbed the server ISO of 15.04 and slapped it on a server. I got started with lxc and lxd to check them out, and while there’s plenty more to do and learn, here’s how to get started with them.

LXD (pronounced lex-dee I’ve heard) is the Daemon based on liblxc offering a REST API to manage containers, specifically the LXC containers. To learn more, checkout Linux Containers is the umbrella project behind LXC, LXD, LXCFS and CGManager. So, let’s get started, shall we?

Install the software

Everything is in the repos, so if you’re in 15.04 you should be good to go. Let’s begin

apt-get update
apt-get install lxd lxd-client lxc lxc-templates python-lxc lua-lxc snappy system-image-snappy-cli

Boom, we’re ready!

Start me up

Start LXD to get the game going

service lxd start

Prepare your user

This kind of setup seems to be something they’ll automate later and have the installer handle, but until then, let’s check some things. Your user should have a uid and gid map defined in /etc/subuid and /etc/subgid. The default should be 65536 for both the uids and gids, so you should be all set in Ubuntu - but if not, use usermod to set your user correctly. then, in `/etc/lxc/lxc-usernet (which is used to set network devices quota for unprivileged users) add a line like this:

your-username veth lxcbr0 10

This just means that “your-username” can create up to 10 veth devices to connect to the lxcbr0 bridge.

Launch some containers

So enough of this, let’s run some instnances. If you checkout Linux Containers you can learn about container names you can download and use, but for now we’ll just use the basic ones.

  • Debian 8 (Jessie)
$ sudo  lxd-images import lxc debian jessie amd64 --alias debian --alias debian/jessie
Downloading the GPG key for https://images.linuxcontainers.org
Downloading the image list for https://images.linuxcontainers.org
Validating the GPG signature of /tmp/tmpel_rn4fq/index.json.asc
Downloading the image: https://images.linuxcontainers.org/images/debian/jessie/amd64/default/20150421_22:42/lxd.tar.xz
Validating the GPG signature of /tmp/tmpel_rn4fq/debian-jessie-amd64-default-20150421_22:42.tar.xz.asc
Image imported as: 7bd9061a169dd5171469034963d1cf683550d28f8706b3a69a0715944e527984
Setup alias: debian
Setup alias: debian/jessie
  • Ubuntu 15.04 (Vivid)
$ sudo lxd-images import lxc ubuntu vivid amd64 --alias ubuntu --alias ubuntu/vivid
sudo lxd-images import lxc ubuntu vivid amd64 --alias ubuntu --alias ubuntu/vivid
Downloading the GPG key for https://images.linuxcontainers.org
Downloading the image list for https://images.linuxcontainers.org
Validating the GPG signature of /tmp/tmphymwwli8/index.json.asc
Downloading the image: https://images.linuxcontainers.org/images/ubuntu/vivid/amd64/default/20150422_03:49/lxd.tar.xz
Validating the GPG signature of /tmp/tmphymwwli8/ubuntu-vivid-amd64-default-20150422_03:49.tar.xz.asc
Image imported as: 98ea382481a29de263d5657ed076893047c8917249ce01ad3b1f4c1f21e341b5
Setup alias: ubuntu
Setup alias: ubuntu/vivid

Easy cheesy, right? Let’s take a look and see what lxc sees running:

$ sudo lxc list
+------------------------+---------+-----------+------+-----------+
|          NAME          |  STATE  |   IPV4    | IPV6 | EPHEMERAL |
+------------------------+---------+-----------+------+-----------+
| trafficless-garfield   | RUNNING | 10.0.3.38 |      | NO        |
| nondiphtherial-shawana | RUNNING |           |      | NO        |
+------------------------+---------+-----------+------+-----------+

Not bad, while I don’t see all of the aliases I added, we clearly see two running!

TODO

Again, I’m just getting started with this, it seems very promising. There’s obviously tons more to do, here are some of them. Once I do I’ll update this post, but feel free to add what you know in the comments, or as a pull request. Remember, we’re all in this together kid!