Can't get streamlink -> ffmpeg -> Snapcast Pipe to work, Permission Denied on pipe

[Drizzt321]

So I'm trying to use Streamlink to playback audio_only endpoints on Twitch to Snapcast named pipe. I'm running (for testing) the command as root, so I'd expect to be able to have full permissions to anything, but yet I'm getting permission denied to the Snapserver named pipe.

Snapcast config

[stream]
source = airplay:///usr/bin/shairport-sync?name=Airplay1&devicename=Airplay1&port=5000
source = pipe:///tmp/streamlink?name=streamlink

Basing my command off of the ffmpeg section in player setup guide

streamlink --stdout --loglevel=none https://www.twitch.tv/theambientmafia audio_only 2>/dev/null | ffmpeg -y -i pipe: -f u16le -acodec pcm_s16le -ac 2 -ar 48000 /tmp/streamlink

I've had to use -y because otherwise ffmpeg would complain File '/tmp/streamlink' already exists. Exiting. I'm running Debian Bullseye, fully up to date, which is Snapserver v0.23.0.

[Drizzt321]

So figured out the problem, the reason I was getting permission denied, even as root, was Protected FIFOs. As per this answer and from this Documentation/sysctl/fs.txt

protected_fifos:

The intent of this protection is to avoid unintentional writes to
an attacker-controlled FIFO, where a program expected to create a regular
file.

When set to "0", writing to FIFOs is unrestricted.

When set to "1" don't allow O_CREAT open on FIFOs that we don't own
in world writable sticky directories, unless they are owned by the
owner of the directory.

When set to "2" it also applies to group writable sticky directories.

I see this is mentioned on the Mopidy section now, just above the ffmpeg section, but not mentioned in the pipes section in the player_setup. So I've gone ahead and created a PR #1130 to add some documentation for it.