Creating an LXD container on Ubuntu 16.04

Published on: Thursday 3 May 2018

I have started getting-to-grips with LXD on Ubuntu -- It's pretty great! LXD makes it possible to separate your applications into containers, and the containers run close to bare metal.

I'm running LXD on my webserver (the one hosting what you're viewing this website on), with four containers:

HAProxy: Used for sending port 80 and 443 requests to the correct container.
Container for running my websites (Apache2, PHP, MySQL, SFTP).
Another container for running client websites, with the same applications as above.
Canonical Landscape: Used to manage my Ubuntu servers and Containers.

Everything has been working well for the past couple of months. I have had no issues updating the containers via Canonical Landscape, and have managed to get some backup scripts running via Cron. I wont go into how the backup scripts work for now, [but will mention this in an upcoming post.]text-decoration: line-through; This post is now live, click here.

Tutorial

Introduction

After looking through multiple tutorials, I have decided to add the steps I found the most useful. It's simple but covers the commands to create, delete and set CPU, Memory and Disk Storage limits.

Setting up the Host

I'm running Ubuntu Server 16.04, each of these commands has worked for me. By default LXD should already be installed.

To start the LXD configuration run:

sudo lxd init

You will be asked some questions. Answer them with these answers:

Do you want to configure a new storage pool (yes/no) [default=yes]? yes
Name of the storage backend to use (dir or zfs) [default=zfs]: zfs
Note: 'ZFS' is able to set storage limits on containers, 'dir' cannot do this. If you're going to use 'ZFS' ensure the package is installed, run:
For ZFS only: a. Do you want to configure a new storage pool (yes/no) [default=yes]? yes b. Name of the storage backend to use (dir or zfs) [default=zfs]: zfs c. Create a new ZFS pool (yes/no) [default=yes]? yes d. Name of the new ZFS pool [default=lxd]: lxd e. Would you like to use an existing block device (yes/no) [default=no]? no f. Size in GB of the new loop device (1GB minimum) [default=15]: 60 -- This is the size of the ZFS pool in GB
Would you like LXD to be available over the network (yes/no) [default=no]? no
Do you want to configure the LXD bridge (yes/no) [default=yes]? yes
Would you like to setup a network bridge for LXD containers now? yes
Bridge name: lxdbr0
Do you want to setup an IPv4 subnet? yes
Accept the default values for IPv4 address and CIDR mask, also accept the default values for DHCP address and maximum DHCP clients
Do you want to NAT the IPv4 traffic? yes
Do you want to setup an IPv6 subnet? no

Once setup, you can run these commands to list the installed containers and the current list of available templates:

Use LXC list to view the available installed containers:
```
sudo lxc list
```
List all available Ubuntu images by running:
```
sudo lxc image list ubuntu:
```
and see all other images by running:
```
sudo lxc image list images:
```

Creating a container

Now create a container named example-webserver running Ubuntu 16.04:

sudo lxc launch ubuntu:16.04 example-webserver

You can set CPU and Memory limits using the following commands:

For CPU:

sudo lxc config set example-webserver limits.cpu 2F

For Memory:

sudo lxc config set example-webserver limits.memory 1024MB

You can also set Hard Drive size limits with ZFS. To limit the hard drive space of a container to 10GB, run the command below:
Note: 'lxd' is the ZFS pool name, the path can be found using: sudo zfs list
```
sudo zfs set quota=10G lxd/containers/example-webserver
```
Once done, you can access the Root File System for for the container here:
```
/var/lib/lxd/containers/example-webserver/rootfs/
```
The above is a symlink to the ZFS path below:
```
/var/lib/lxd/containers/example-webserver.zfs/rootfs/
```

List and View ZFS Pools

To list ZFS pools, run:

sudo zfs list

To see the ZFS pool status, run:

zpool status -v

Listing all available containers

To list all created containers, run:

sudo lxc list

Or to see the configured specs of a specific container (Replace example-webserver with your container name), run:

sudo lxc config show example-webserver

Stop, Start and Delete containers

Note: Replace example-webserver with your container name.

To stop:
```
lxc stop example-webserver
```
To restart:
```
lxc start example-webserver
```
To delete:
```
lxc delete example-webserver
```

Logging into Containers

Note: Replace example-webserver with your container name.

To access the shell of a container, run:

sudo lxc exec example-webserver -- sudo --login --user ubuntu

Now run any commands on this container, such as installing Apache2, etc.

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