prometheus-node-exporter-lua: add basic hwmon exporter

This collector supports following metrics:

 * node_hwmon_temp_celsius
 * node_hwmon_pwm

and following auxiliary mappings:

 * node_hwmon_chip_names
 * node_hwmon_sensor_label

Tested on:

 * Banana Pi BPI-r3 / OpenWrt 23.05.0-rc2
 * TP-Link Archer C7 v5 / OpenWrt 22.03.5

Signed-off-by: Ivan Mironov <mironov.ivan@gmail.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/utils/prometheus-node-exporter-lua/files/usr/lib/lua/prometheus-collectors/hwmon.lua b/utils/prometheus-node-exporter-lua/files/usr/lib/lua/prometheus-collectors/hwmon.lua
new file mode 100644
index 000000000..3e00f0524
--- /dev/null
+++ b/utils/prometheus-node-exporter-lua/files/usr/lib/lua/prometheus-collectors/hwmon.lua
@@ -0,0 +1,58 @@
+#!/usr/bin/lua
+
+local fs = require "nixio.fs"
+
+local function rtrim(s)
+  return string.gsub(s, "\n$", "")
+end
+
+local function scrape()
+  local metric_chip_names = metric("node_hwmon_chip_names", "gauge")
+  local metric_sensor_label = metric("node_hwmon_sensor_label", "gauge")
+  local metric_temp_celsius = metric("node_hwmon_temp_celsius", "gauge")
+  local metric_pwm = metric("node_hwmon_pwm", "gauge")
+
+  for hwmon_path in fs.glob("/sys/class/hwmon/hwmon*") do
+    -- Produce node_hwmon_chip_names
+    -- See https://github.com/prometheus/node_exporter/blob/7c564bcbeffade3dacac43b07c2eeca4957ca71d/collector/hwmon_linux.go#L415
+    local chip_name = rtrim(get_contents(hwmon_path .. "/name"))
+    if chip_name == "" then
+      chip_name = fs.basename(hwmon_path)
+    end
+
+    -- See https://github.com/prometheus/node_exporter/blob/7c564bcbeffade3dacac43b07c2eeca4957ca71d/collector/hwmon_linux.go#L355
+    local chip = chip_name
+    local real_dev_path, status = fs.realpath(hwmon_path .. "/device")
+    if not status then
+      local dev_name = fs.basename(real_dev_path)
+      local dev_type = fs.basename(fs.dirname(real_dev_path))
+      chip = dev_type .. "_" .. dev_name
+    end
+    metric_chip_names({chip=chip, chip_name=chip_name}, 1)
+
+    -- Produce node_hwmon_sensor_label
+    for sensor_path in fs.glob(hwmon_path .. "/*_label") do
+      local sensor = string.gsub(fs.basename(sensor_path), "_label$", "")
+      local sensor_label = rtrim(get_contents(sensor_path))
+      metric_sensor_label({chip=chip, sensor=sensor, label=sensor_label}, 1)
+    end
+
+    -- Produce node_hwmon_temp_celsius
+    for sensor_path in fs.glob(hwmon_path .. "/temp*_input") do
+      local sensor = string.gsub(fs.basename(sensor_path), "_input$", "")
+      local temp = get_contents(sensor_path) / 1000
+      metric_temp_celsius({chip=chip, sensor=sensor}, temp)
+    end
+
+    -- Produce node_hwmon_pwm
+    for sensor_path in fs.glob(hwmon_path .. "/pwm*") do
+      local sensor = fs.basename(sensor_path)
+      if string.match(sensor, "^pwm[0-9]+$") then
+        local pwm = rtrim(get_contents(sensor_path))
+        metric_pwm({chip=chip, sensor=sensor}, pwm)
+      end
+    end
+  end
+end
+
+return { scrape = scrape }