make xrootd run as pid 2

etc/systemd/nspawn/xcache.nspawn

@@ -4,13 +4,18 @@ BindReadOnly=/etc/grid-security
 BindReadOnly=/etc/xrootd
 
 [Exec]
-PrivateUsers=False
+#PrivateUsers=False
 
 # This might be one way to deal with permissions of bind mounts
 # e.g. if the xrootd user inside the container has user id 999 it will consistently
 # become 655360 + 999 on the host system
-#PrivateUsers=655360
-#PrivateUsersOwnership=chown
+PrivateUsers=655360
+PrivateUsersOwnership=chown
+
+Boot=False
+ProcessTwo=True
+Parameters=/usr/bin/xrootd -c /etc/xrootd/xcache.cfg
+User=xrootd
 
 # Enable this to always make temporary containers (don't write back to the image)
 #Ephemeral=True