Update: Saturday 10^th February 2024.
Update: Wednesday 28^th February 2024.
Update: Friday 19^th September 2025.

TL;DR.

LXD (LinuX Daemon) is a container manager for creating and managing containers. LXCs (LinuX Containers) are isolated system instances where anything within the container can NOT affect other containers or the base distro/OS. Also, multiple container instances can run concurrently on a single host.

Attributions:

https://ubuntu.com/lxd↗.

An Introduction.

This is a concise (read: less rambling) version of a post from 2023. This time around, I will be more specific about my intentions for this adapted chronicle.

The purpose of this post is to present the installation, and likely uses, of LXD/LXC.

The Big Picture.

Containers are considered the Second Wave of System Isolation Technologies. The First Wave were virtual machines and the Third Wave are WASM/WASI binaries. Each Wave brought their own strengths and weaknesses.

Prerequisites.

• A Linux-based distro (I use Ubuntu).

Updating the System.

• I update my system:

sudo apt clean && \
sudo apt update && \
sudo apt dist-upgrade -y && \
sudo apt --fix-broken install && \
sudo apt autoclean && \
sudo apt autoremove -y

What is LXD and LXC?

The LXD (LinuX Daemon) is the container manager that is used to create, and manage, LXCs (LinuX Containers). It is a background service that can automatically start LXCs when the host system boots, or stop any container from starting at all.

An LXC (LinuX Container) is an isolated, OS-level virtualization which, for efficiency, uses the Linux kernel of the host system. An LXC is a virtual environment where system processes within the LXC container can not affect other containers, or the host system, without specifically running certain commands.

https://ubuntu.com/server/docs/containers-lxd↗,

https://ubuntu.com/server/docs/containers-lxc↗, and

https://solodev.app/installing-lxd-and-using-lxcs.

Installing the LXD.

• I install the snap package manager, if required:

sudo apt install -y snapd

• I install the LXD manager:

sudo snap install lxd

• I find the name of my host interface:

ip addr

NOTE: My host interface name for the NIC (network interface card) is enp6s0.

• I initialise the LXD:

sudo lxd init

NOTE: When initialized, the host interface (enp6s0) will become available to the LXD manager. Now the LXD manager can connect to the router and ask for IP addresses for any running containers.

Troubleshooting.

• I run a simple LXC command:

lxc ls

• Running the LXC command may result in one of these errors:

Error: Failed to connect to local LXD: Get "http://unix.socket/1.0": dial unix /var/snap/lxd/common/lxd/unix.socket: connect: permission denied
bash: /usr/sbin/lxc: No such file or directory

• To fix this issue, I provide access to the LXD group for my current account:

sudo usermod -aG lxd $(whoami)

• I change the GID (group ID) for the LXD manager:

newgrp lxd

• I test these changes by running the LXC command again:

lxc ls

Deleting the LXD.

• I can delete the LXD, if required:

sudo snap remove --purge lxd

NOTE: The --purge flag removes everything, including configuration files, etc.

Setting Up an LXC.

• I list the existing containers:

lxc ls

• I launch a new container called Default:

lxc launch ubuntu:22.04 Default

• I bash into the container:

lxc exec Default -- bash

• I update and upgrade the container:

sudo apt clean && \
sudo apt update && \
sudo apt dist-upgrade -y && \
sudo apt --fix-broken install && \
sudo apt autoclean && \
sudo apt autoremove -y

Adding a User Account to the LXC.

• From within the container, I add a new user:

adduser yt

• I add the new user to the sudo group:

usermod -aG sudo yt

NOTE: usermod let's me (-a)ppend the sudo (-G)roup to the yt account.

• I exit the container:

exit

NOTE: I exit the root account to use the yt account.

Setting the LXC Home Directory.

• From the terminal, I log in to the container with the yt account:

lxc exec Default -- su yt

NOTE: At the moment, the home directory is /root. This section will address the issue by changing the home directory to ~.

• I use the Nano text editor to open the .bashrc file:

sudo nano ~/.bashrc

• I copy the following, add it (CTRL + SHIFT + V) to the bottom of the .bashrc file, save (CTRL +S) the changes, and exit (CTRL + X) Nano:

cd ~

Hardening the Container.

• From within the container, I use the Nano text editor to open the sshd_config file:

sudo nano /etc/ssh/sshd_config

• I copy the following, add it (CTRL + SHIFT + V) to the bottom (CTRL + END) of the sshd_config file, save (CTRL +S) the changes, and exit (CTRL + X) Nano:

PasswordAuthentication no
PermitRootLogin no
Protocol 2
Port 22

NOTE: Port 22 is the default, so I'll choose my own, random, available port number.

• I restart the "ssh" service:

sudo systemctl restart ssh.service

• I reboot the container:

sudo reboot

NOTE: Within the container, I can also install (or enable) UFW, Fail2Ban, and CrowdSec.

23 Common Commands.

Here is a list of 23 commands that maybe somewhat useful. Although I commonly use only a handful of commands from this list, it's nice to have a reference on file:

1. lxc --version to check the version (and if the command doesn't work, then I'd know an installation problem occurred),

2. lxc network list to list all the network adapters,

3. lxc init ubuntu:22.04 test-container3 to download an Ubuntu container,

4. lxc launch ubuntu:22.04 test-container3 to launch an Ubuntu container,

5. lxc storage ls to list storage pool,

6. lxc list or lxc ls to list all the images and containers,

7. lxc stop test-container3 to stop a container,

8. lxc start test-container3 to start a container,

9. lxc restart test-container3 to restart a container,

10. lxc stop test-container3 followed by lxc delete test-container3, or lxc stop test-container3 -f to delete a container,

11. lxc exec test-container3 cat /etc/os-release to execute a command on the container,

12. lxc info test-container3 to check a container's Information,

13. lxc exec test-container3 -- bash to get root access to a container,

14. lxc exec test-container3 -- su mylogin to get account access to a container,

15. lxc copy test-container3 test-container3-clone to copy a container,

16. lxc image list images: | grep -i centos to list prebuilt images,

17. lxc network show lxdbr0 to display information about network interface(s),

18. lxc profile show default to check the default profile using lxc command,

19. lxc snapshot test-container3 test-container3_snap followed by lxc info test-container3 to take snapshot of an instance,

20. lxc restore test-container3 test-container3_snap to restore an instance from a snapshot,

21. lxc export test-container3 /root/backup/lxd/test-container3_bkp--$(date +'%m-%d-%Y').tar.xz --optimized-storage to take backup of an instance,

22. lxc import /root/backup/lxd/test-container3_bkp--05-07-2022.tar.xz followed by lxc list to restore instance from a backup, and

23. lxc --help to check all the options that are available to an LXC command.

Attribution:

https://www.cyberithub.com/20-best-lxc-command-examples-to-manage-linux-containers/

The Results.

LXD and LXC provide a powerful, flexible, and resource-efficient way to run isolated system instances on a single host. This technology represents the second wave of system isolation technologies, offering certain advantages over traditional virtual machines. The process of installing LXD and using LXC may seem complex at first, but once I understood the basics and familiarized myself with common commands, I could create, manage, and delete containers with ease. Whether I'm setting up a homelab or deploying applications in a production environment, mastering LXD/LXC is a valuable skill.

In Conclusion.

LXD and LXC was a revolutionary system isolation technology. LXD (Linux Daemon) is a container manager that allows me to create and manage containers. LXCs (Linux Containers), on the other hand, are isolated system instances. They ensure that anything within the container doesn't affect other containers or the base operating system. This means multiple container instances can run concurrently on a single host.

Containers are considered the Second Wave of System Isolation Technologies. The First Wave were virtual machines and the Third Wave are WASM/WASI binaries. Each Wave brought their own strengths and weaknesses.

LXD and LXC provide a powerful, flexible, and resource-efficient way to run isolated system instances on a single host. This technology offers certain advantages over traditional virtual machines, making it a valuable skill to master.

Once I understood the basics, I could create, manage, and delete containers with ease. Whether setting up a homelab or deploying applications in a production environment, adopting LXD/LXC was a game-changer.

So, have you used LXD and LXC in your projects? What's your experience been like? Share your thoughts in the comments below!

Until next time: Be safe, be kind, be awesome.

NOTE: All images generated by ComfyUI using the dreamshaper_8 checkpoint.