# 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) and survives system
updates.

## 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.

### 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
```


## Updating Tailscale

⚠️ 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.

## 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/