only create app user if it doesn't exist

src/app/startup.sh

@@ -5,8 +5,10 @@ while ! pg_isready -h $DB_HOST -U $DB_USER; do
 	sleep 3
 done
 
+if ! id app; then
 	addgroup -g $OWNER_GID app
 	adduser -D -h /var/www/html -G app -u $OWNER_UID app
+fi
 
 DST_DIR=/var/www/html/tt-rss
 SRC_DIR=/src/tt-rss/

src/app/updater.sh

@@ -3,8 +3,10 @@
 # wait for the app container to delete .app_is_ready and perform rsync, etc.
 sleep 30
 
+if ! id app; then
 	addgroup -g $OWNER_GID app
 	adduser -D -h /var/www/html -G app -u $OWNER_UID app
+fi
 
 while ! pg_isready -h $DB_HOST -U $DB_USER; do
 	echo waiting until $DB_HOST is ready...