music: Update mpd-volume-to-mqtt script

roles/music/templates/mpd-volume-to-mqtt.sh

@@ -0,0 +1,21 @@
+# {{ ansible_managed }}
+
+#!/bin/bash
+
+set -eu
+set -o pipefail
+
+
+trap 'mqtt-simple -h {{ mqtt_internal_host }} -p '{{ music_mqtt_mpd_volume }}' -m "" -r' EXIT
+
+prev_volume=x
+
+(echo mixer; mpc idleloop) | while read event; do
+    if [ $event = "mixer" ]; then
+        volume=`mpc volume | sed -nr 's/^volume: ([0-9]+)%$/\1/p'`
+        if [ "$prev_volume" != "$volume" ]; then
+            mqtt-simple -h {{ mqtt_internal_host }} -p '{{ music_mqtt_mpd_volume }} -r' -m "$volume"
+        fi
+        prev_volume=$volume
+    fi
+done