vnstat2: add hotplug script for adding interfaces

If an interface doesn't exist yet when vnStat is started, it won't be
monitored, as only existing interfaces can be added to the database via
the vnstat command.

This adds a hotplug script which adds any configured interfaces to the
vnStat database when it goes up.

Signed-off-by: Jan Hoffmann <jan@3e8.eu>

net/vnstat2/Makefile

@@ -77,6 +77,8 @@ define Package/vnstat2/install
 	$(INSTALL_CONF) ./files/vnstat.config $(1)/etc/config/vnstat
 	$(INSTALL_DIR) $(1)/etc/init.d
 	$(INSTALL_BIN) ./files/vnstat.init $(1)/etc/init.d/vnstat
+	$(INSTALL_DIR) $(1)/etc/hotplug.d/iface
+	$(INSTALL_DATA) ./files/vnstat.hotplug $(1)/etc/hotplug.d/iface/50-vnstat
 endef
 
 define Package/vnstati2/install

net/vnstat2/files/vnstat.hotplug

@@ -0,0 +1,23 @@
+/etc/init.d/vnstat running || exit 0
+[ "$ACTION" = "ifup" ] || exit 0
+
+. /lib/functions.sh
+
+check_iface() {
+	local iface="$1"
+
+	[ "$iface" = "$DEVICE" ] || return
+
+	/usr/bin/vnstat --add -i "$iface" >/dev/null
+
+	exit 0
+}
+
+check_ifaces() {
+	local cfg="$1"
+
+	config_list_foreach "$cfg" interface check_iface
+}
+
+config_load vnstat
+config_foreach check_ifaces vnstat