Trying out LXD containers on Ubuntu on DigitalOcean

You can have LXD containers on your home computer, you can also have them on your Virtual-Private Server (VPS). If you have any further questions on LXD, see https://www.stgraber.org/2016/03/11/lxd-2-0-blog-post-series-012/

Here we see how to configure on a VPS at DigitalOcean (yeah, referral). We go cheap and select the 512MB RAM and 20GB disk VPS for $5/month. Containers are quite lightweight, so it’s interesting to see how many we can squeeze. We are going to use ZFS for the storage of the containers, stored on a file and not a block device. Here is what we are doing today,

  1. Set up LXD on a 512MB RAM/20GB diskspace VPS
  2. Create a container with a web server
  3. Expose the container service to the Internet
  4. Visit the webserver from our browser

Set up LXD on DigitalOcean

do-create-droplet

When creating the VPS, it is important to change these two options; we need 16.04 (default is 14.04) so that it has ZFS pre-installed as a kernel module, and we try out the cheapest VPS offering with 512MB RAM.

Once we create the VPS, we connect with

$ ssh root@128.199.41.205    # change with the IP address you get from the DigitalOcean panel
The authenticity of host '128.199.41.205 (128.199.41.205)' can't be established.
ECDSA key fingerprint is SHA256:7I094lF8aeLFQ4WPLr/iIX4bMs91jNiKhlIJw3wuMd4.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added '128.199.41.205' (ECDSA) to the list of known hosts.
Welcome to Ubuntu 16.04 LTS (GNU/Linux 4.4.0-24-generic x86_64)

* Documentation: https://help.ubuntu.com/

0 packages can be updated.
0 updates are security updates.

root@ubuntu-512mb-ams3-01:~# apt update
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [94.5 kB]
Hit:2 http://ams2.mirrors.digitalocean.com/ubuntu xenial InRelease 
Get:3 http://security.ubuntu.com/ubuntu xenial-security/main Sources [24.9 kB]
...
Fetched 10.2 MB in 4s (2,492 kB/s)
Reading package lists... Done
Building dependency tree 
Reading state information... Done
13 packages can be upgraded. Run 'apt list --upgradable' to see them.
root@ubuntu-512mb-ams3-01:~# apt upgrade
Reading package lists... Done
Building dependency tree 
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
 dnsmasq-base initramfs-tools initramfs-tools-bin initramfs-tools-core
 libexpat1 libglib2.0-0 libglib2.0-data lshw python3-software-properties
 shared-mime-info snapd software-properties-common wget
13 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 6,979 kB of archives.
After this operation, 78.8 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
...
Processing triggers for initramfs-tools (0.122ubuntu8.1) ...
update-initramfs: Generating /boot/initrd.img-4.4.0-24-generic
W: mdadm: /etc/mdadm/mdadm.conf defines no arrays.
Processing triggers for libc-bin (2.23-0ubuntu3) ...

We update the package list and then upgrade any packages that need upgrading.

root@ubuntu-512mb-ams3-01:~# apt policy lxd
lxd:
 Installed: 2.0.2-0ubuntu1~16.04.1
 Candidate: 2.0.2-0ubuntu1~16.04.1
 Version table:
 *** 2.0.2-0ubuntu1~16.04.1 500
 500 http://mirrors.digitalocean.com/ubuntu xenial-updates/main amd64 Packages
 500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
 100 /var/lib/dpkg/status
 2.0.0-0ubuntu4 500
 500 http://mirrors.digitalocean.com/ubuntu xenial/main amd64 Packages

The lxd package is already installed, all the better. Nice touch 🙂

root@ubuntu-512mb-ams3-01:~# apt install zfsutils-linux
Reading package lists... Done
Building dependency tree 
Reading state information... Done
The following additional packages will be installed:
 libnvpair1linux libuutil1linux libzfs2linux libzpool2linux zfs-doc zfs-zed
Suggested packages:
 default-mta | mail-transport-agent samba-common-bin nfs-kernel-server
 zfs-initramfs
The following NEW packages will be installed:
 libnvpair1linux libuutil1linux libzfs2linux libzpool2linux zfs-doc zfs-zed
 zfsutils-linux
0 upgraded, 7 newly installed, 0 to remove and 0 not upgraded.
Need to get 881 kB of archives.
After this operation, 2,820 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
...
zed.service is a disabled or a static unit, not starting it.
Processing triggers for libc-bin (2.23-0ubuntu3) ...
Processing triggers for systemd (229-4ubuntu6) ...
Processing triggers for ureadahead (0.100.0-19) ...
root@ubuntu-512mb-ams3-01:~# _

We installed zfsutils-linux in order to be able to use ZFS as storage for our containers. In this tutorial we are going to use a file as storage (still, ZFS filesystem) instead of a block device. If you subscribe to the DO Beta for block storage volumes, you can get a proper block device for the storage of the containers. Currently free to beta members, available only on the NYC1 datacenter.

root@ubuntu-512mb-ams3-01:~# df -h /
Filesystem Size Used Avail Use% Mounted on
/dev/vda1  20G  1.1G 18G     6% /
root@ubuntu-512mb-ams3-01:~# _

We got 18GB free diskspace, so let’s allocate 15GB for LXD.

root@ubuntu-512mb-ams3-01:~# lxd init
Name of the storage backend to use (dir or zfs): zfs
Create a new ZFS pool (yes/no)? yes
Name of the new ZFS pool: lxd-pool
Would you like to use an existing block device (yes/no)? no
Size in GB of the new loop device (1GB minimum): 15
Would you like LXD to be available over the network (yes/no)? no
Do you want to configure the LXD bridge (yes/no)? yes
we accept the default settings for the bridge configuration
Warning: Stopping lxd.service, but it can still be activated by:
 lxd.socket
LXD has been successfully configured.
root@ubuntu-512mb-ams3-01:~# _

What we did,

  • we initialized LXD with the ZFS storage backend,
  • we created a new pool and gave a name (here, lxd-pool),
  • we do not have a block device, so we get a (sparse) image file that contains the ZFS filesystem
  • we do not want now to make LXD available over the network
  • we want to configure the LXD bridge for the inter-networking of the containters

Let’s create a new user and add them to the lxd group,

root@ubuntu-512mb-ams3-01:~# adduser ubuntu
Adding user `ubuntu' ...
Adding new group `ubuntu' (1000) ...
Adding new user `ubuntu' (1000) with group `ubuntu' ...
Creating home directory `/home/ubuntu' ...
Copying files from `/etc/skel' ...
Enter new UNIX password: ********
Retype new UNIX password: ********
passwd: password updated successfully
Changing the user information for ubuntu
Enter the new value, or press ENTER for the default
 Full Name []: <ENTER>
 Room Number []: <ENTER>
 Work Phone []: <ENTER>
 Home Phone []: <ENTER>
 Other []: <ENTER>
Is the information correct? [Y/n] Y
root@ubuntu-512mb-ams3-01:~# _

The username is ubuntu. Make sure you add a good password, since we do not deal in this tutorial with best security practices. Many people use scripts on these VPSs that try common usernames and passwords. When you create a VPS, it is nice to have a look at /var/log/auth.log for those failed attempts to get into your VPS. Here are a few lines from this VPS,

Jun 26 18:36:15 digitalocean sshd[16318]: Failed password for root from 121.18.238.29 port 45863 ssh2
Jun 26 18:36:15 digitalocean sshd[16320]: Connection closed by 123.59.134.76 port 49378 [preauth]
Jun 26 18:36:17 digitalocean sshd[16318]: Failed password for root from 121.18.238.29 port 45863 ssh2
Jun 26 18:36:20 digitalocean sshd[16318]: Failed password for root from 121.18.238.29 port 45863 ssh2

We add the ubuntu user into the lxd group in order to be able to run commands as a non-root user.

root@ubuntu-512mb-ams3-01:~# adduser ubuntu lxd
Adding user `ubuntu' to group `lxd' ...
Adding user ubuntu to group lxd
Done.
root@ubuntu-512mb-ams3-01:~# _

We are now good to go. Log in as user ubuntu and run an LXD command to list images.

do-lxc-list

Create a Web server in a container

We launch (init and start) a container named c1.

do-lxd-launch

The ubuntu:x in the screenshot is an alias for Ubuntu 16.04 (Xenial), that resides in the ubuntu: repository of images. You can find other distributions in the images: repository.

As soon as the launch action was completed, I run the list action. Then, after a few seconds, I run it again. You can notice that it took a few seconds before the container actually booted and got an IP address.

Let’s enter into the container by executing a shell. We update and then upgrade the container.

ubuntu@ubuntu-512mb-ams3-01:~$ lxc exec c1 -- /bin/bash
root@c1:~# apt update
Get:1 http://security.ubuntu.com/ubuntu xenial-security InRelease [94.5 kB]
Hit:2 http://archive.ubuntu.com/ubuntu xenial InRelease
Get:3 http://archive.ubuntu.com/ubuntu xenial-updates InRelease [94.5 kB]
...
Fetched 9819 kB in 2s (3645 kB/s) 
Reading package lists... Done
Building dependency tree 
Reading state information... Done
13 packages can be upgraded. Run 'apt list --upgradable' to see them.
root@c1:~# apt upgrade
Reading package lists... Done
Building dependency tree 
Reading state information... Done
Calculating upgrade... Done
The following packages will be upgraded:
 dnsmasq-base initramfs-tools initramfs-tools-bin initramfs-tools-core libexpat1 libglib2.0-0 libglib2.0-data lshw python3-software-properties shared-mime-info snapd
 software-properties-common wget
13 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 6979 kB of archives.
After this operation, 3339 kB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 initramfs-tools all 0.122ubuntu8.1 [8602 B]
...
Processing triggers for initramfs-tools (0.122ubuntu8.1) ...
Processing triggers for libc-bin (2.23-0ubuntu3) ...
root@c1:~#

Let’s install nginx, our Web server.

root@c1:~# apt install nginx
Reading package lists... Done
Building dependency tree 
Reading state information... Done
The following additional packages will be installed:
 fontconfig-config fonts-dejavu-core libfontconfig1 libfreetype6 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libtiff5 libvpx3 libxpm4 libxslt1.1 nginx-common nginx-core
Suggested packages:
 libgd-tools fcgiwrap nginx-doc ssl-cert
The following NEW packages will be installed:
 fontconfig-config fonts-dejavu-core libfontconfig1 libfreetype6 libgd3 libjbig0 libjpeg-turbo8 libjpeg8 libtiff5 libvpx3 libxpm4 libxslt1.1 nginx nginx-common nginx-core
0 upgraded, 15 newly installed, 0 to remove and 0 not upgraded.
Need to get 3309 kB of archives.
After this operation, 10.7 MB of additional disk space will be used.
Do you want to continue? [Y/n] Y
Get:1 http://archive.ubuntu.com/ubuntu xenial/main amd64 libjpeg-turbo8 amd64 1.4.2-0ubuntu3 [111 kB]
...
Processing triggers for ufw (0.35-0ubuntu2) ...
root@c1:~#

Is the Web server running? Let’s check with the ss command (preinstalled, from package iproute2)

root@c1:~# ss -tula 
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port 
udp UNCONN 0 0 *:bootpc *:* 
tcp LISTEN 0 128 *:http *:* 
tcp LISTEN 0 128 *:ssh *:* 
tcp LISTEN 0 128 :::http :::* 
tcp LISTEN 0 128 :::ssh :::*
root@c1:~#

The parameters mean

  • -t: Show only TCP sockets
  • -u: Show only UDP sockets
  • -l: Show listening sockets
  • -a: Show all sockets (makes no difference because of previous options; it’s just makes an easier word to remember, tula)

Of course, there is also lsof with the parameter -i (IPv4/IPv6).

root@c1:~# lsof -i
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
dhclient 240 root 6u IPv4 45606 0t0 UDP *:bootpc 
sshd 306 root 3u IPv4 47073 0t0 TCP *:ssh (LISTEN)
sshd 306 root 4u IPv6 47081 0t0 TCP *:ssh (LISTEN)
nginx 2034 root 6u IPv4 51636 0t0 TCP *:http (LISTEN)
nginx 2034 root 7u IPv6 51637 0t0 TCP *:http (LISTEN)
nginx 2035 www-data 6u IPv4 51636 0t0 TCP *:http (LISTEN)
nginx 2035 www-data 7u IPv6 51637 0t0 TCP *:http (LISTEN)
root@c1:~#

From both commands we verify that the Web server is indeed running inside the VPS, along with a SSHD server.

Let’s change a bit the default Web page,

root@c1:~# nano /var/www/html/index.nginx-debian.html

do-lxd-nginx-page

Expose the container service to the Internet

Now, if we try to visit the public IP of our VPS at http://128.199.41.205/ we obviously notice that there is no Web server there. We need to expose the container to the world, since the container only has a private IP address.

The following iptables line exposes the container service at port 80. Note that we run this as root on the VPS (root@ubuntu-512mb-ams3-01:~#), NOT inside the container (root@c1:~#).

iptables -t nat -I PREROUTING -i eth0 -p TCP -d 128.199.41.205/32 --dport 80 -j DNAT --to-destination 10.160.152.184:80

Adapt accordingly the public IP of your VPS and the private IP of your container (10.x.x.x). Since we have a web server, this is port 80.

We have not made this firewall rule persistent as it is outside of our scope; see iptables-persistent on how to make it persistent.

Visit our Web server

Here is the URL, http://128.199.41.205/ so let’s visit it.

do-lxd-welcome-nginx

That’s it! We created an LXD container with the nginx Web server, then exposed it to the Internet.

 

Permanent link to this article: https://blog.simos.info/trying-out-lxd-containers-on-ubuntu-on-digitalocean/

9 comments

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    • Nic on July 13, 2016 at 23:55
    • Reply

    Thank you so much for this guide!
    I couldn’t figure out how to do this, and it really helped, many thanks!

    • michael on October 6, 2016 at 21:54
    • Reply

    you are a life saver

    • michael on October 6, 2016 at 22:43
    • Reply

    Do you know how to properly point domain directly to the containers ip address on a server with multiple containers ?

    • Steve on October 28, 2016 at 03:20
    • Reply

    Right on!
    Glad you wrote this.

  1. @michael:

    If you have several containers with, for example, Web servers, then you would use a “reverse proxy” to direct each connection to the correct container.

    One such software for “reverse proxy” is HAProxy. See https://simos.info/blog/how-to-set-up-multiple-secure-ssltls-qualys-ssl-labs-a-websites-using-lxd-containers/ on how to set it up.

    1. In most situations, beside HAProxy is already used, iptables would be more than enough

      1. If it is a single website, then it’s fine to use iptables.

        If you wanted several websites, with each to have SSL/TLS support, then you would need an SNI proxy (such as HAProxy).

        There is an updated guide on LXD on Digitalocean at https://www.digitalocean.com/community/tutorials/how-to-set-up-and-use-lxd-on-ubuntu-16-04

  2. Thank you for this. I have been looking for something like this without success and I am happy I found it.

  3. I’ve been following your LXD/haproxy stuff lately and think it’s fantastic! I like the recent Hetzner Cloud guides as well. Was wondering if you have heard of Turnkey LXC? I’m sure you know of Turnkey Linux and their appliances, but I just stumbled upon their LXC model for their Turnkey appliances, which is kind of similar to what you are doing with haproxy/lxd:

    https://www.turnkeylinux.org/lxc

    Anyway, I love the lxc/lxd model, with haproxy or some other reverse proxy container (nginx whatever) handling the domain based load balancing and SSL. All very interesting stuff!!

    I like the idea though of sticking with haproxy/lxd, but perhaps utilize the Turnkey LXC images for some services/applications/domains. There is probably an easy way to convert LXC images to LXD, or can you just use any LXC image out of the box with LXD? Thanks for any feedback!

  1. […] have seen how to try out LXD containers on Ubuntu on DigitalOcean. In this post, we will see how to use the new DigitalOcean block storage support (just out of […]

  2. […] That’s it! LXD is up and running, and we successfully created a container. See these instructions on how to test the container with a Web server. […]

  3. […] previous posts we saw how to set up LXD on a DigitalOcean VPS, how to set up LXD on a Scaleway VPS, and how the lifecycle of an LXD container looks […]

  4. […] previous posts, we saw how to configure LXD/LXC containers on a VPS on DigitalOcean and Scaleway. There are many more VPS […]

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