the /run/dbus directory needs to be defined.

docker/Dockerfile

@@ -124,7 +124,8 @@ RUN apk -U add \
     adduser -D shairport-sync -G shairport-sync && \
     addgroup -g 29 docker_audio && \
     addgroup shairport-sync docker_audio && \
-    addgroup shairport-sync audio
+    addgroup shairport-sync audio && \
+    mkdir -p /run/dbus
 
 # Remove anything we don't need.
 # Remove any statically-defined Avahi services, e.g. SSH and SFTP

docker/classic/Dockerfile

@@ -104,4 +104,7 @@ RUN rm -rf /etc/avahi/services/*.service
 COPY ./docker/run.sh ./run.sh
 RUN chmod +x /run.sh
 
+# D-Bus might need this directory
+RUN mkdir -p /run/dbus
+
 ENTRYPOINT ["/init","./run.sh"]