Operations Overview

This section covers day-to-day operation of the Shiloh Broadcaster system.

Sections

• Systemd Units — user-mode units, linger, dependency ordering, socket activation
• Monitoring & Logs — log locations, verbose stats, health checks, alerting
• Security — firewall, WireGuard, allow-lists, control plane isolation
• Performance Tuning — JACK buffers, CPU priority, network socket tuning

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Ports

State files

All files live in ~/mixer-state/ by default (override in the TOML).

These files are the only coupling between shiloh-mixer and mixer_web. There is no inter-process socket between them.

systemd units (user-mode)

All services run as the shiloh user with systemctl --user. No root or sudo is required for day-to-day operation.

Starting / stopping

# Start all services
systemctl --user start shiloh-mixer shiloh-web-relay mixer_web

# Stop all services
systemctl --user stop shiloh-mixer shiloh-web-relay mixer_web

# Restart a single service
systemctl --user restart shiloh-mixer

# Enable auto-start on login
systemctl --user enable shiloh-mixer shiloh-web-relay mixer_web

Logs

# Follow live
journalctl --user -u shiloh-mixer -f
journalctl --user -u shiloh-web-relay -f
journalctl --user -u mixer_web -f

# Last 50 lines
journalctl --user -u shiloh-mixer -n 50

# Since a specific time
journalctl --user -u shiloh-mixer --since "30 min ago"

Unit locations

~/.config/systemd/user/shiloh-mixer.service
~/.config/systemd/user/shiloh-web-relay.service
~/.config/systemd/user/mixer_web.service

After editing a unit file: systemctl --user daemon-reload.

Updating binaries

Mixer server update

# Binary (built locally or downloaded)
systemctl --user stop shiloh-mixer
cp target/release/shiloh-mixer ~/mixer/shiloh-mixer-linux-x86_64
systemctl --user start shiloh-mixer

# Web relay binary
systemctl --user stop shiloh-web-relay
cp target/release/shiloh-web-relay ~/mixer/shiloh-web-relay-linux-x86_64
systemctl --user start shiloh-web-relay

# mixer_web Phoenix release
# (deploy method depends on your CI; typically tar extract to ~/mixer_web/)
systemctl --user restart mixer_web

NOTE: shiloh-mixer sends BYE to all connected relay clients when it stops cleanly. They reconnect automatically within the backoff window (1–30 s). Broadcaster senders also reconnect automatically.

Relay client update

# On the relay machine
cp new/shiloh-relay ~/.local/bin/shiloh-relay
systemctl --user restart shiloh-relay  # if running as a service
# or kill and restart manually

WirePlumber: keep hardware devices awake

PipeWire suspends ALSA devices after ~5 s of inactivity. When the device sleeps, the JACK graph has no hardware clock driver and all processing stalls — VU meters show 0.0 even though JACK connections look correct.

Drop this into ~/.config/wireplumber/wireplumber.conf.d/53-keep-devices-awake.conf (adjust node.name patterns to match your hardware — check names with pactl list short sinks):

monitor.alsa.rules = [
  {
    matches = [
      { node.name = "~alsa_(output|input).usb-Burr-Brown.*" }
      { node.name = "~alsa_(output|input).usb-Focusrite_Scarlett.*" }
    ]
    actions = {
      update-props = {
        session.suspend-timeout-seconds = 0
      }
    }
  }
]

Apply: systemctl --user restart wireplumber

Verify: timeout 2 pw-top -b -n 3 — at least one ALSA node should show status R with non-zero QUANT/RATE.

Desktop audio null sink (PipeWire)

To route Firefox, VLC, and other PulseAudio apps into the mixer, create a persistent PipeWire null sink. Create ~/.config/pipewire/pipewire.conf.d/desktop-audio-sink.conf:

context.objects = [
  { factory = adapter
    args = {
      factory.name     = support.null-audio-sink
      node.name        = desktop-audio
      node.description = "Desktop Audio"
      media.class      = Audio/Sink
      audio.position   = [ FL FR ]
      monitor.channel-volumes = true
      object.linger    = true
    }
  }
]

NOTE: Do not add an adapter.auto-port-config block. WirePlumber negotiates the adapter’s port-config and a pre-applied auto-port-config deadlocks WpSiAudioAdapter activation. Symptom: apps are stuck at Corked: yes in pavucontrol and every stream goes to Sink: 4294967295.

Apply: systemctl --user restart pipewire pipewire-pulse wireplumber

MIDI control

shiloh-midi-sender reads a USB MIDI keyboard and forwards note-on events as raw UDP to the mixer’s MIDI listener on port 19999. The mixer runs a modal state machine to translate key presses into fader/mute/scene actions and Ardour OSC transport commands.

Running the MIDI sender

shiloh-midi-sender --device "USB MIDI" --server stg-srv001.bq.shilohbv.com:19999

Key map (default config)

Mode entry (C3 octave):

Channel navigation (in ChannelSelect / ChannelControl):

Channel actions (C5 octave, in ChannelControl):

Transport (C6 octave, in Transport mode):

The MIDI panel in the web UI shows the current mode, the last 8 keys pressed, and the action each key triggered. Keys that produced no action (not mapped in the current mode) show —.

Key mappings are configured in [midi.*] blocks in shiloh-mixer.toml. After changing them, redeploy the TOML and restart the mixer.

Ardour integration

shiloh-mixer can control and receive feedback from Ardour over OSC and Ardour’s WebSocket surface.

One-time Ardour setup

1. Edit → Preferences → Control Surfaces → Open Sound Control → Show Protocol Settings
2. Enable OSC, listen port: 3819
3. Reply port: 3820, enable feedback on strips and master (fader + mute)
4. Click Apply

Install / update the Ardour session template

The template is generated live from the running mixer config:

mkdir -p ~/.config/ardour8/templates/shiloh-broadcast
curl http://localhost:8889/ardour/template \
  -o ~/.config/ardour8/templates/shiloh-broadcast/shiloh-broadcast.template

Re-run after changing the channel layout.

Recovery after PipeWire upgrade

PipeWire upgrades can reset JACK port state. Restart the mixer and web UI:

systemctl --user restart shiloh-mixer mixer_web

If the graph doesn’t recover (all meters at 0.0):

systemctl --user restart pipewire pipewire-pulse wireplumber
# then:
systemctl --user restart shiloh-mixer