I got a little bug when I testing my VyOS 1.17 configuration in beta 999.201704292137.
vyos@mia-test# commit [ service dns forwarding system ] Global symbol "$query_all_servers" requires explicit package name at /opt/vyatta/sbin/vyatta-dns-forwarding.pl line 98. Execution of /opt/vyatta/sbin/vyatta-dns-forwarding.pl aborted due to compilation errors. [[service dns forwarding]] failed Commit failed 
Steps to reproduce:
configure set service dns forwarding listen-on eth0 set service dns forwarding system commit