162 lines
5.4 KiB
Markdown
162 lines
5.4 KiB
Markdown
---
|
|
title: "Crash Course to LXD"
|
|
subtitle: "Quick instructions for installing LXD and setting up your first application."
|
|
date: 2023-09-19T14:27:00-04:00
|
|
categories:
|
|
- Technology
|
|
tags:
|
|
- Sysadmin
|
|
- Containers
|
|
- VMs
|
|
- Docker
|
|
- LXD
|
|
draft: false
|
|
toc: true
|
|
rss_only: false
|
|
cover: ./cover.png
|
|
---
|
|
|
|
If you're wondering _why_ I like system containers, see the previous post, _[LXD: Containers for
|
|
Human Beings.][lxd]_
|
|
|
|
[lxd]: {{< ref "lxd-containers-for-human-beings" >}}
|
|
|
|
## Installation
|
|
|
|
{{< adm type="note" >}}
|
|
|
|
**Note:** the instructions below say to install LXD using [Snap.][snap] I
|
|
personally dislike Snap, but LXD is a Canonical product and they're doing their
|
|
best to promote it as much as possible. [Incus] is a fork of LXD by the primary
|
|
creators and maintainers and one of the first things they did was [rip out Snap
|
|
support,][rsnap] so it will eventually be installable as a proper native
|
|
package.
|
|
|
|
[snap]: https://en.wikipedia.org/wiki/Snap_(software)
|
|
[Incus]: https://github.com/lxc/incus
|
|
[rsnap]: https://github.com/lxc/incus/compare/9579f65cd0f215ecd847e8c1cea2ebe96c56be4a...3f64077a80e028bb92b491d42037124e9734d4c7
|
|
|
|
{{< /adm >}}
|
|
|
|
1. Install snap following [Canonical's tutorial](https://earl.run/ZvUK)
|
|
- LXD is natively packaged for Arch and Alpine, but configuration can be a
|
|
massive headache.
|
|
2. `sudo snap install lxd`
|
|
3. `lxd init`
|
|
- Defaults are fine for the most part; you may want to increase the size of
|
|
the storage pool.
|
|
4. `lxc launch images:debian/12 container-name`
|
|
5. `lxc shell container-name`
|
|
|
|
## Usage
|
|
|
|
As an example of how to use LXD in a real situation, we'll set up [my URL
|
|
shortener.][earl] You'll need a VPS with LXD installed and a (sub)domain pointed
|
|
to the VPS.
|
|
|
|
Run `lxc launch images:debian/12 earl` followed by `lxc shell earl` and `apt
|
|
install curl`. Also `apt install` a text editor, like `vim` or `nano` depending
|
|
on what you're comfortable with. Head to the **Installation** section of [earl's
|
|
SourceHut page][earl] and expand the **List of latest binaries**. Copy the link
|
|
to the binary appropriate for your platform, head back to your terminal, type
|
|
`curl -LO`, and paste the link you copied. This will download the binary to your
|
|
system. Run `mv <filename> earl` to rename it, `chmod +x earl` to make it
|
|
executable, then `./earl` to execute it. It will create a file called
|
|
`config.yaml` that you need to edit before proceeding. Change the `accessToken`
|
|
to something else and replace the `listen` value, `127.0.0.1`, with `0.0.0.0`.
|
|
This exposes the application to the host system so we can reverse proxy it.
|
|
|
|
[earl]: https://earl.run/source
|
|
|
|
The next step is daemonising it so it runs as soon as the system boots. Edit the
|
|
file located at `/etc/systemd/system/earl.service` and paste the following code
|
|
snippet into it.
|
|
|
|
```ini
|
|
[Unit]
|
|
Description=personal link shortener
|
|
After=network.target
|
|
|
|
[Service]
|
|
User=root
|
|
Group=root
|
|
WorkingDirectory=/root/
|
|
ExecStart=/root/earl -c config.yaml
|
|
|
|
[Install]
|
|
WantedBy=multi-user.target
|
|
```
|
|
|
|
Save, then run `systemctl daemon-reload` followed by `systemctl enable --now
|
|
earl`. You should be able to `curl localhost:8275` and see some HTML.
|
|
|
|
Now we need a reverse proxy on the host. Exit the container with `exit` or
|
|
`Ctrl+D`, and if you have a preferred webserver, install it. If you don't have a
|
|
preferred webserver yet, I recommend [installing Caddy.][caddy] All that's left
|
|
is running `lxc list`, making note of the `earl` container's `IPv4` address, and
|
|
reverse proxying it. If you're using Caddy, edit `/etc/caddy/Caddyfile` and
|
|
replace everything that's there with the following.
|
|
|
|
[caddy]: https://caddyserver.com/docs/install
|
|
|
|
```text
|
|
<(sub)domain> {
|
|
encode zstd gzip
|
|
reverse_proxy <container IP address>:1313
|
|
}
|
|
```
|
|
|
|
Run `systemctl restart caddy` and head to whatever domain or subdomain you
|
|
entered. You should see the home page with just the text `earl` on it. If you go
|
|
to `/login`, you'll be able to enter whatever access token you set earlier and
|
|
log in.
|
|
|
|
## Further tips
|
|
|
|
One of the things you might want to do post-installation is mess around with
|
|
profiles. There's a `default` profile in LXD that you can show with `lxc profile
|
|
show default`.
|
|
|
|
```text
|
|
$ lxc profile show default
|
|
config: {}
|
|
description: Default LXD profile
|
|
devices:
|
|
eth0:
|
|
name: eth0
|
|
network: lxdbr0
|
|
type: nic
|
|
root:
|
|
path: /
|
|
pool: default
|
|
type: disk
|
|
name: default
|
|
used_by: []
|
|
```
|
|
|
|
Not all config options are listed here though; you'll need to read [the
|
|
documentation] for a full enumeration.
|
|
|
|
[the documentation]: https://documentation.ubuntu.com/lxd/en/latest/config-options/
|
|
|
|
I've seen some people say that executing a fork bomb from inside a container is
|
|
equivalent to executing it on the host. The fork bomb will blow up the whole
|
|
system and render every application and container you're running inoperable.
|
|
That's partially true because LXD _by default_ doesn't put a limit on how many
|
|
processes a particular container can spawn. You can limit that number yourself
|
|
by running
|
|
|
|
```text
|
|
lxc profile set default limits.processes <num-processes>
|
|
```
|
|
|
|
Any container you create under the `default` profile will have a total process
|
|
limit of `<num-processes>`. I can't tell you what a good process limit is
|
|
though; you'll need to do some testing and experimentation on your own.
|
|
|
|
As stated in [the containers section][pp] of the previous post, this doesn't
|
|
_save_ you from fork bombs. It just helps prevent a fork bomb from affecting the
|
|
host OS or other containers.
|
|
|
|
[pp]: {{< ref "lxd-containers-for-human-beings#containers" >}}
|