[Bug] Deskthing itself and it's Apps are completely broken on NixOS

[inkstray]

NOTE: I am unsure how to submit decent logs for this, please. I'd appreciate some help to submit a better bug report

This was attempted on latest stable release of NixOS (25.11) using the appimage-run package and alsa-utils installed, also tailscale was used to get a device to finally connect to it.

Running the "local music" app crashes the entire Deskthing AppImage and running the binary its supposed to run causes a segfault

Segmentation fault         (core dumped) ./n-nowplaying.linux-x64-gnu.node

thread '<unnamed>' panicked at /home/runner/.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/tracing-subscriber-0.3.19/src/util.rs:91:14:
failed to set global default subscriber: SetGlobalDefaultError("a global default trace dispatcher has already been set")
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
fatal runtime error: failed to initiate panic, error 5

Also what i noted is that the server/client gives these error(s):

server 6:15:32 PM AppProcessStore(spawnProcess): Process audio encountered the error: Error: Error - Command failed with ENOENT: amixer
spawn amixer ENOENT. STACK: Error: Command failed with ENOENT: amixer
spawn amixer ENOENT
    at ChildProcess._handle.onexit (node:internal/child_process:285:19)
    at onErrorNT (node:internal/child_process:483:16)
    at process.processTicksAndRejections (node:internal/process/task_queues:82:21). Cause: No cause.
Command failed with ENOENT: amixer
spawn amixer ENOENT

server 6:15:32 PM AppStore(handleProcessError): Process error for audio: Error: Undefined value received.

app 6:15:32 PM AppProcessStore(spawnProcess): Process audio exited with non-zero code: 1

server 6:15:32 PM AppStore(handleProcessError): Process error for audio: Error: Undefined value received.

server 6:15:32 PM AppStore(handleProcessError): Process exited for audio: Error: Undefined value received.

server 6:16:02 PM undefined: App audio is not found or not running

server 6:07:39 PM statsFetchWrapper(register): Failed to register client: 403 - Forbidden. Registering with headers {"Content-Type":"application/json","X-Client-ID":"833364f2400154679c3a39bf75e2d50197c8edea3af65c7517be32888d8608a1","X-Signature":"rc3eS+MV9ZYMYYaslrXVR7SX3tbxVVPxomhPmQk+8wlfzmCuJRTLoyCSo+aN5hSQFoJ9OLXmqZtPryFMHcKVAA=="} and registration data: {"id":"833364f2400154679c3a39bf75e2d50197c8edea3af65c7517be32888d8608a1","publicKey":"V45YzrDqKddvnNHNzsp7gAbxCwJNYtfF/+/6FOGisCQ=","os":"linux","cpus":8,"memory":15644987392}

server 6:07:39 PM statsStore(initialize): Stats store initialized

server 6:07:39 PM statsStore(register): Failed to register
Failed to register client: Forbidden

[GarntS]

I just got angry and fixed this for myself.

TL;DR - The "Local Audio" app has a nodejs package as a dependency, loudness. loudness spawns an amixer process that crashes because it doesn't have a full environment. I'm not sure why this behavior is different on nixos vs other distros, maybe someone else knows.

One issue at a time:

1. Your segfault was caused because n-nowplaying.linux-x64-gnu.node isn't actually an executable, it's a shared library (written in Rust) that gets pulled in by some nodejs bindings. Source for that binary is in this repo.
2. The audio process exiting is because the "Local Audio" plugin exits in the event that the operation using the loudness library fails.
3. The statsStore/statsFetchWrapper stuff I have no idea about, but it doesn't prevent things from working so I don't super care.

To resolve this, you'll need to:

1. Pull loudness from here, and modify node-loudness/impl/linux.js. Details below.
2. Pull the deskthing-apps repo from here, and modify its package.json to pull in your locally-modified copy of the loudness package instead of the one it's using.
3. Run npm run build from within deskthing-apps/audio, which will build a zip file of the app.
4. Import the zip file into DeskThing by clicking "Add App" on the bottom left of the Downloads page.
5. In the DeskThing settings, under "Music", set "Playback Sources" to "Local Audio".

Modifying node-loudness/impl/linux.js:

If you're just using ALSA, you can modify the amixer function as follows, adjust the 0 argument to correspond to your default output device:

async function amixer (...args) {
  return (await execa('amixer', ['-c', '0'].concat(args))).stdout
}

Alternatively, I re-wrote it to work with pipewire via wpctl instead. Feel free to just bum my implementation:

const execa = require('execa')

async function wpctl (...args) {
  return (await execa('wpctl', args, { env: { XDG_RUNTIME_DIR: '/run/user/1000', DBUS_SESSION_BUS_ADDRESS: 'unix:path=/run/user/1000/bus' } })).stdout
}

const DEFAULT_SINK_STR = '@DEFAULT_AUDIO_SINK@';

const reInfo = /Volume\: ([01]\.\d+) ?(\[MUTED\])?/

function parseInfo (data) {
  const result = reInfo.exec(data)

  if (result === null) {
    throw new Error('wpctl Error: failed to parse output\n'+ data)
  }

  return { volume: Math.floor(parseFloat(result[1]) * 100), muted: (result[2] === '[MUTED]') }
}

async function getInfo () {
  return parseInfo(await wpctl('get-volume', DEFAULT_SINK_STR))
}

exports.getVolume = async function getVolume () {
  return (await getInfo()).volume
}

exports.setVolume = async function setVolume (val) {
  await wpctl('set-volume', DEFAULT_SINK_STR, val + '%')
}

exports.getMuted = async function getMuted () {
  return (await getInfo()).muted
}

exports.setMuted = async function setMuted (val) {
  await wpctl('set-mute', DEFAULT_SINK_STR, val ? '1' : '0')
}

[inkstray]

THANK YOU!!!