prometheus/node: add textfile collector sensors (WIP cont'd)

2 files changed, 40 insertions, 6 deletions

diff --git a/roles/monitoring/prometheus/exporter/node/templates/textfile-collector-scripts/sensors.j2 b/roles/monitoring/prometheus/exporter/node/templates/textfile-collector-scripts/sensors.j2
index 822aa3b5..1e769389 100644
--- a/roles/monitoring/prometheus/exporter/node/templates/textfile-collector-scripts/sensors.j2
+++ b/roles/monitoring/prometheus/exporter/node/templates/textfile-collector-scripts/sensors.j2
@@ -1,5 +1,8 @@
 #!/usr/bin/lua5.1
 
+local sys_stat = require "posix.sys.stat"
+local state_filename = '/run/prometheus-node-exporter_sensors/state'
+
 local sensors = require "sensors"
 local units = {
     temperature = "celsius",
@@ -37,14 +40,46 @@ local function scrape(config, num_sensors)
     end
 end
 
-function main()
-    local config, _ = sensors.read_config('/etc/prometheus/exporter/node/sensors.json')
-
-    -- TODO: only do this if sensor state file does not exist - else read num_sensors from state file
+local function _setup(config)
     local num_sensors, err = sensors.setup(config)
     if num_sensors == nil then error(err) end
-    -- TODO: write num_sensors to state file
+    io.stderr:write(string.format("setup: %d sensors found.\n", num_sensors))
+
+    local f, err = io.open(state_filename, "w")
+    if not f then error(err) end
+    local ret, err = f:write(string.format("%d\n", num_sensors))
+    f:close()
+    if not ret then error(err) end
+
+    return num_sensors
+end
+
+local function setup(config)
+    local s, _ = sys_stat.stat(state_filename)
+    if s == nil then
+        return _setup(config)
+    end
+
+    local f, err = io.open(state_filename, "r")
+    if not f then error(err) end
+    local data, err = f:read("*l")
+    f:close()
+    if not data then
+        return _setup(config)
+    end
+
+    local num_sensors, err = tonumber(data)
+    if num_sensors == nil then
+        return _setup(config)
+    end
+    return num_sensors
+end
+
+function main()
+    local config, err = sensors.read_config('/etc/prometheus/exporter/node/sensors.json')
+    if config == nil then error(err) end
 
+    local num_sensors = setup(config)
     scrape(config, num_sensors, units)
 end
 
diff --git a/roles/monitoring/prometheus/exporter/node/templates/textfile-collector-scripts/sensors.service.j2 b/roles/monitoring/prometheus/exporter/node/templates/textfile-collector-scripts/sensors.service.j2
index 7a438317..a9f2a8fb 100644
--- a/roles/monitoring/prometheus/exporter/node/templates/textfile-collector-scripts/sensors.service.j2
+++ b/roles/monitoring/prometheus/exporter/node/templates/textfile-collector-scripts/sensors.service.j2
@@ -18,7 +18,6 @@ PrivateTmp=true
 ProtectControlGroups=true
 ProtectHome=true
 ProtectKernelModules=true
-ProtectKernelTunables=true
 ProtectSystem=strict
 ReadWritePaths=/var/lib/prometheus-node-exporter/textfile-collector
 RuntimeDirectory=prometheus-node-exporter_sensors