# Tailscale on the Steam Deck

This process is derived from the [official guide][official-guide], but has been
tweaked to make the process smoother and produce an installation that comes up
automatically on boot (no need to enter desktop mode).

## Installing Tailscale

1. Clone this repo to your Deck.
2. Run `sudo bash tailscale.sh` to install Tailscale (or update the existing
   installation).
3. Run `sudo tailscale up --qr --operator=deck --ssh` to have Tailscale generate
   a login QR code. Scan the code with your phone and authenticate with
   Tailscale to bring your Deck onto your network.

## Updating Tailscale

Tailscale should be able to update itself now! Try running
`sudo tailscale update`, and if that works, `sudo tailscale set --auto-update`.
If it doesn't, keep reading.

> ⚠️ This process will most likely fail if you are accessing the terminal over
> Tailscale SSH, as it seems to be locked in a chroot jail. You should start and
> connect through the standard SSH server instead, but remember to stop it when
> you're done.
> [Suggestions for how to fix this are welcomed.](https://github.com/legowerewolf/deck-tailscale/issues/2)

1. Git fetch and pull to make sure you're up to date.
2. Run `sudo bash tailscale.sh` again.

This process overwrites the existing binaries and service file, so it's not
recommended to tweak those files directly. The configuration files at
`/etc/default/tailscaled` and
`/etc/systemd/system/tailscaled.service.d/override.conf` are left alone, so feel
free to edit those. If something goes wrong, copy those files somewhere else and
re-run the install script to get back to a working state.

## Changing the root filesystem after installing Tailscale

This method for installing Tailscale uses
[`systemd` system extensions](https://man.archlinux.org/man/systemd-sysext.8.en)
to install files in the otherwise read-only Steam Deck filesystem. A side-effect
is that the `/usr` and `/opt` directories (and directories like `/bin`, `/lib`,
`/lib64`, `/mnt`, and `/sbin`, that typically link to `/usr` due to
[`/usr` merge](https://www.freedesktop.org/wiki/Software/systemd/TheCaseForTheUsrMerge/)
which SteamOS implements) are read-only while system extensions are active,
_even after running `steamos-readonly disable`_.

If you need to modify files in these directories after installing Tailscale, run
the following commands:

```bash
$ systemd-sysext unmerge
$ steamos-readonly disable
[ make your changes to the rootfs now ]
$ steamos-readonly enable
$ systemd-sysext merge
```

## On system update

Unfortunately, because SteamOS doesn't include a `SYSEXT_LEVEL`, this
installation method breaks when the system version changes. Repair is simple:
Re-run the second step of the installation, and everything should come back up
as you had it.

### Why this happens

Extension images have to declare their compatibility using the OS ID and either
the SYSEXT_LEVEL or VERSION_ID, which have to match what the system declares.

SteamOS doesn't declare a SYSEXT_LEVEL, and the VERSION_ID increments with every
system update, so there's no stable values to declare compatibility against.

## Common issues

### Broken config file (#10)

Symptom: `invalid value "" for flag -port: can't be the empty string`

Resolution: Delete `/etc/default/tailscaled` and re-run installer script.

## How it works

It uses the same system extension method as the official guide, but we put the
`tailscaled.service` file directly in `/etc/systemd/system/` because it's
actually safe to put things there. Changes in `/etc/` are preserved in
`/var/lib/overlays/etc/upper/` via an overlayfs, meaning that they survive
updates.

[official-guide]: https://tailscale.com/blog/steam-deck/