tested for $HOSTUID before trying to attempt to change the UID for www-data in the php box

Author: easterncoder

docker/php/Dockerfile

@@ -1,9 +1,9 @@
 ARG PHPVER
 FROM php:${PHPVER}-fpm
 
-# set www-data to our host user's UID
+# attempt to set www-data's UID to our host user's UID
 ARG HOSTUID
-RUN usermod -u $HOSTUID www-data; groupmod -g $HOSTUID www-data
+CMD [ "$HOSTUID" -gt "1" ] && usermod -u $HOSTUID www-data && groupmod -g $HOSTUID www-data
 
 # Install some stuff
 RUN apt-get update -y && apt-get install -y sendmail libpng-dev