s6 overlay improvements.

docker/Dockerfile

@@ -1,4 +1,4 @@
-FROM alpine AS builder
+FROM alpine:3.12 AS builder
 
 # Check required arguments exist. These will be provided by the Github Action
 # Workflow and are required to ensure the correct branches are being used.
@@ -67,7 +67,7 @@ RUN make install
 ##### SPS END #####
 
 # Shairport Sync Runtime System
-FROM crazymax/alpine-s6:edge
+FROM crazymax/alpine-s6:3.12-edge
 
 RUN apk -U add \
         alsa-lib \
@@ -107,4 +107,6 @@ RUN addgroup -g 29 docker_audio && addgroup shairport-sync docker_audio && addgr
 # Remove anything we don't need.
 RUN rm -rf /lib/apk/db/*
 
-ENTRYPOINT [ "/init" ]
+ENTRYPOINT [ "/init" ]
+
+CMD /usr/local/bin/shairport-sync -vu --statistics

docker/README.md

@@ -36,10 +36,11 @@ To get access to the full range of configuration options, pass the configuration
 ### Build Example (for arm7 devices)
 
 ```
-docker buildx build --platform linux/arm/v7 -f ./docker/Dockerfile --build-arg SHAIRPORT_SYNC_BRANCH=development --build-arg NQPTP_BRANCH=development -t shairport-sync:unstable-development .
+docker buildx build --platform linux/arm/v7 -f ./docker/Dockerfile --build-arg SHAIRPORT_SYNC_BRANCH=development --build-arg NQPTP_BRANCH=development --no-cache -t shairport-sync:unstable-development .
 ```
 
 `SHAIRPORT_SYNC_BRANCH` and `NQPTP_BRANCH` are required to ensure the image is built using the expected branch.
+`--no-cache` needs to be used to force buildx to pull the NQPTP branch for new updates. This slows down the build time though so can be removed when it is not beneficial during testing.
 
 ### AirPlay 1 Only
 

docker/etc/services.d/02-avahi/run

@@ -1,2 +1,9 @@
-#!/usr/bin/execlineb -P
-avahi-daemon --no-chroot
+#!/bin/sh
+avahi-daemon --check
+if [ $? -eq 0 ]; then
+  echo "Reloading avahi-daemon."
+  avahi-daemon --no-chroot --reload
+else
+  echo "Starting avahi-daemon."
+  avahi-daemon --no-chroot
+fi

docker/etc/services.d/03-nqptp/run

@@ -1,2 +1,2 @@
 #!/usr/bin/execlineb -P
-/usr/local/bin/nqptp
+/usr/local/bin/nqptp -v

docker/etc/services.d/04-shairport-sync/finish

@@ -1,2 +0,0 @@
-#!/usr/bin/execlineb -S0
-s6-svscanctl -t /var/run/s6/services

docker/etc/services.d/04-shairport-sync/run

@@ -1,2 +0,0 @@
-#!/usr/bin/execlineb -P
-/usr/local/bin/shairport-sync -vu --statistics