Node start VLC Player with child_process

Question

I have a POST function in which I am trying to start VLC player using the child_process. I am using the latest Raspbian version.

router.post('/', function (req, res) {
    let spawn = require('child_process').spawn;
    let vlc = spawn('vlc');
    vlc.stderr.on('data', function(data) {
        console.log(data.toString());
    });
    vlc.on('exit', function(code){
        console.log('Exit code: ' + code);
    });
    res.send({success: true})
});

After triggering the request, I get this message:

VLC is not supposed to be run as root. Sorry. If you need to use real-time priorities and/or privileged TCP ports you can use vlc-wrapper (make sure it is Set-UID root and cannot be run by non-trusted users first).

Since VLC cannot be run as root, I added the UID argument to the vlc start script, and it now looks like this:

let vlc = spawn('vlc' ,{uid: 1000});

Where UID: 1000 is the ID of the user I always use.

After triggering the request, I get another message in the log:

[016f9960] main libvlc error: cannot open config file (/root/.config/vlc/vlcrc): Permission denied

Home directory not accessible: Permission denied

[01762eb0] vlcpulse audio output error: PulseAudio server connection failure: Connection refused

[0176bde8] dbus interface error: Failed to connect to the D-Bus session daemon: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11

[0176bde8] main interface error: no suitable interface module [016f9960] main libvlc error: interface "dbus,none" initialization failed

[0176c7a8] main interface error: no suitable interface module [016f9960] main libvlc error: interface "globalhotkeys,none" initialization failed

[016f9960] main libvlc: Running vlc with the default interface. Use 'cvlc' to use vlc without interface.

error: XDG_RUNTIME_DIR not set in the environment.

[0176c7a8] skins2 interface error: cannot initialize OSFactory

[017614e0] main playlist: playlist is empty

[0176c7a8] [cli] lua interface: Listening on host "*console".

The player doesn't run. But if I run the same command via ssh, it will run. What could cause node from not running it?

Dino Dino · Accepted Answer · 2019-01-06T19:23:52

The problem was that my server was running using

nodemon

I literally tried everything, and then when I was about to give up, I accidentally started server the normal way using node command. The VLC is starting without any errors. I didn't have to pass any user ID in arguments. It works fine just like this:

let spawn = require('child_process').spawn;
let vlc = spawn('vlc');

I'm really curious why nodemon could cause such a behaviour.

Node start VLC Player with child_process

1 Answers