netplug: T3130: add VyOS specific helper script

data/live-build-config/includes.chroot/etc/netplug/netplug

@@ -0,0 +1,29 @@
+#!/bin/sh
+#
+# vyos policy agent for netplugd
+#
+
+dev="$1"
+action="$2"
+
+case "$action" in
+in)
+   run-parts -a $dev /etc/netplug/linkup.d
+    ;;
+out)
+   run-parts -a $dev /etc/netplug/linkdown.d
+    ;;
+
+# probe loads and initialises the driver for the interface and brings the
+# interface into the "up" state, so that it can generate netlink(7) events.
+# This interferes with "admin down" for an interface. Thus, commented out. An
+# "admin up" is treated as a "link up" and thus, "link up" action is executed.
+# To execute "link down" action on "admin down", run appropriate script in
+# /etc/netplug/linkdown.d
+#probe)
+#    ;;
+
+*)
+    exit 1
+    ;;
+esac