Linksys Velop WRT Pro 7 のメトリックスを Amazon CloudWatch で可視化する

-- The Linksys Velop WRT Pro 7 cannot use prometheus-node-exporter-lua-wifi_stations:
-- its interface discovery (`ubus call network.wireless status`) always returns
-- {} because this firmware's wifi-device type ("qcawificfg80211", QCA/QSDK) is
-- never registered with netifd's wireless subsystem, and even with interfaces
-- read from UCI instead, iwinfo's assoclist() always returns nil for that
-- device type, so no per-station data is available through iwinfo.
--
-- This collector instead shells out to hostapd_cli, which talks to the
-- per-radio hostapd control socket at /var/run/hostapd-<device>/<ifname>
-- and returns real station stats (signal, inactive time, tx/rx counters)
-- regardless of the iwinfo/ubus limitation.
--
-- Do not `opkg install prometheus-node-exporter-lua-wifi_stations` -- it
-- will overwrite this file with the non-functional upstream version.

local uci = require("uci")

local cursor = uci.cursor()

local function gauge(name)
 return metric(name, "gauge")
end

local function counter(name)
 return metric(name, "counter")
end

local metric_wifi_stations = gauge("wifi_stations")
local station_metrics = {
 { field = "signal", metric = gauge("wifi_station_signal_dbm") },
 { field = "inactive_msec", metric = gauge("wifi_station_inactive_milliseconds") },
 { field = "tx_packets", metric = counter("wifi_station_transmit_packets_total") },
 { field = "rx_packets", metric = counter("wifi_station_receive_packets_total") },
 { field = "tx_bytes", metric = counter("wifi_station_transmit_bytes_total") },
 { field = "rx_bytes", metric = counter("wifi_station_receive_bytes_total") },
}

-- hostapd_cli's `all_sta` output is a flat station MAC address line
-- followed by its "key=value" attribute lines, repeated per station. If
-- hostapd_cli can't reach the control socket, it prints an error line
-- instead (e.g. "Failed to connect to hostapd - ..."); the MAC check below
-- keeps that from being mistaken for a station.
local function parse_stations(output)
 local stations = {}
 local current
 for line in output:gmatch("[^\n]+") do
  local key, value = line:match("^(%w[%w_]*)=(.*)$")
  if key and current then
   current[key] = value
  elseif line:match("^%x%x:%x%x:%x%x:%x%x:%x%x:%x%x$") then
   current = {}
   stations[line] = current
  else
   current = nil
  end
 end
 return stations
end

local function scrape()
 -- Interfaces are independent hostapd control sockets, so every
 -- `hostapd_cli` process is started before any of them are read back --
 -- the wait time is bounded by the slowest socket instead of their sum.
 local procs = {}
 cursor:foreach("wireless", "wifi-iface", function(section)
  local ifname = section.ifname
  local device = section.device
  if not ifname or not device then
   return
  end

  local proc =
   io.popen(string.format("hostapd_cli -p '/var/run/hostapd-%s' -i '%s' all_sta 2>/dev/null", device, ifname))
  if proc then
   procs[#procs + 1] = { ifname = ifname, proc = proc }
  end
 end)

 for _, p in ipairs(procs) do
  local output = p.proc:read("*a")
  p.proc:close()

  local count = 0
  for mac, sta in pairs(parse_stations(output)) do
   count = count + 1
   local labels = { ifname = p.ifname, mac = mac }

   for _, sm in ipairs(station_metrics) do
    local value = sta[sm.field]
    if value then
     sm.metric(labels, tonumber(value))
    end
   end
  end

  metric_wifi_stations({ ifname = p.ifname }, count)
 end
end

return { scrape = scrape }

receivers:
  prometheus:
    config:
      scrape_configs:
        - job_name: openwrt
          scrape_interval: 60s
          static_configs:
            - targets:
                - openwrt:9100

processors:
  transform:
    error_mode: ignore
    metric_statements:
      - context: metric
        statements:
          - convert_sum_to_gauge() where metric.name == "node_time_seconds"
  cumulativetodelta: {}
  batch:
    send_batch_size: 200
    timeout: 10s

exporters:
  otlphttp:
    metrics_endpoint: https://monitoring.ap-northeast-1.amazonaws.com/v1/metrics
    auth:
      authenticator: sigv4auth

extensions:
  sigv4auth:
    region: ap-northeast-1
    service: monitoring

service:
  extensions:
    - sigv4auth
  pipelines:
    metrics:
      receivers:
        - prometheus
      processors:
        - transform
        - cumulativetodelta
        - batch
      exporters:
        - otlphttp