Add monit for /var/log disk usage (#1836)

Signed-off-by: Qi Luo <[email protected]>

Author: qiluo-msft

build_debian.sh

@@ -269,6 +269,8 @@ sudo sed -i '
 sudo tee -a $FILESYSTEM_ROOT/etc/monit/monitrc > /dev/null <<'EOF'
 check filesystem root-aufs with path /
   if space usage > 90% for 5 times within 10 cycles then alert
+check filesystem var-log with path /var/log
+  if space usage > 90% for 5 times within 10 cycles then alert
 check system $HOST
   if memory usage > 90% for 5 times within 10 cycles then alert
   if cpu usage (user) > 90% for 5 times within 10 cycles then alert