prometheus-node-exporter-lua: fix hostapd stations

We can only utilize statistics from interfaces having ubus interface.

Signed-off-by: Nick Hainke <vincent@systemli.org>

utils/prometheus-node-exporter-lua/Makefile

@@ -4,7 +4,7 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=prometheus-node-exporter-lua
-PKG_VERSION:=2022.06.29
+PKG_VERSION:=2022.08.07
 PKG_RELEASE:=1
 
 PKG_MAINTAINER:=Etienne CHAMPETIER <champetier.etienne@gmail.com>

utils/prometheus-node-exporter-lua/files/usr/lib/lua/prometheus-collectors/hostapd_stations.lua

@@ -1,15 +1,40 @@
 local ubus = require "ubus"
 local bit32 = require "bit32"
 
+local function get_wifi_interfaces()
+  local conn = ubus.connect()
+  local ubuslist = conn:objects()
+  local interfaces = {}
+
+  for _,net in ipairs(ubuslist) do
+    if net.find(net,"hostapd.") then
+      local ifname = net:gsub("hostapd.", "")
+      table.insert(interfaces, ifname);
+    end
+  end
+  conn:close()
+  return interfaces;
+end
+
+local function is_ubus_interface(ubus_interfaces, interface)
+  for i=1,#ubus_interfaces do
+    if ubus_interfaces[i] == interface then return true end
+  end
+  return false
+end
+
 local function get_wifi_interface_labels()
   local u = ubus.connect()
   local status = u:call("network.wireless", "status", {})
   local interfaces = {}
+  local ubus_interfaces = get_wifi_interfaces()
 
   for _, dev_table in pairs(status) do
     for _, intf in ipairs(dev_table['interfaces']) do
       local cfg = intf['config']
 
+      if is_ubus_interface(ubus_interfaces, cfg['ifname']) then
+
         -- Migrate this to ubus interface once it exposes all interesting labels
         local handle = io.popen("hostapd_cli -i " .. cfg['ifname'] .." status")
         local hostapd_status = handle:read("*a")
@@ -49,6 +74,7 @@ local function get_wifi_interface_labels()
         table.insert(interfaces, labels)
       end
     end
+  end
 
   return interfaces
 end