temperatures

// The temperatures of a Linux host, by SNMP, from lmTempSensorsTable (LM-SENSORS-MIB), which net-snmp
// serves when it is built with lm_sensors and the machine has sensors: a virtual machine has none. With no
// sensor read, the collector stops and says so, rather than stay green on nothing.
// The temperature reads in thousandths of a degree: lmTempSensorsTemperature, signed, when the agent
// serves it, otherwise the older lmTempSensorsValue. Two sensors of the same name ("temp1" on two chips)
// each keep their own: the second carries its index.
need('protocol:snmp');

per('sensor', 'Sensors');
output('temperature', 'number', array('label' => 'Temperature', 'unit' => '°C', 'per' => 'sensor'));

watch.above('hot', 'High temperature', 'temperature', array('warning' => 80, 'critical' => 95, 'for' => '3 runs'));

// lmTempSensorsTable, by lmTempSensorsIndex: lmTempSensorsDevice (the sensor's name), lmTempSensorsValue
// and lmTempSensorsTemperature.
$sensors = snmp.table(array(
    'name'        => '1.3.6.1.4.1.2021.13.16.2.1.2',
    'value'       => '1.3.6.1.4.1.2021.13.16.2.1.3',
    'temperature' => '1.3.6.1.4.1.2021.13.16.2.1.4',
));

$read = 0;
$seen = array();
foreach ($sensors as $index => $row) {
    $milli = list.get($row, 'temperature', list.get($row, 'value', ''));
    if (!list.has($row, 'name') || $milli == '') {
        continue;
    }
    $name = $row['name'];
    if (list.has($seen, $name)) {
        $name = $name . ' #' . $index;
    }
    $seen[$name] = true;
    $read = $read + 1;
    value('temperature', number.round($milli / 1000, 1), $name);
}
if ($read == 0) {
    fail('misconfigured', 'The agent serves no temperature (lmTempSensorsTable, LM-SENSORS-MIB)',
        'net-snmp built without lm_sensors, or a machine without sensors, such as a virtual machine.');
}