added dockerfile for user-specific nc

compose/nextcloud-fpm/docker-compose.yml

@@ -35,7 +35,8 @@ services:
       - MYSQL_USER=nextcloud
 
   app:
-    image: nextcloud:fpm
+#    image: nextcloud:fpm
+    build: ./nc-fpm
     restart: always
     links:
       - db

compose/nextcloud-fpm/nc-fpm/Dockerfile

@@ -0,0 +1,4 @@
+FROM nextcloud:fpm
+
+RUN adduser --system --no-create-home --home /nonexistent --gecos 'www-data user' --shell /bin/false --uid 82 www-data
+