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Health Information

Sensors

This document will guide you through adding health / sensor information for your new device.

Currently we have support for the following health metrics along with the values we expect to see the data in:

Class Measurement
airflow cfm
ber ratio
charge %
chromatic_dispersion ps/nm
cooling W
count #
current A
dbm dBm
delay s
eer eer
fanspeed rpm
frequency Hz
humidity %
load %
loss %
power W
power_consumed kWh
power_factor ratio
pressure kPa
quality_factor dB
runtime Min
signal dBm
snr SNR
state #
temperature C
voltage V
waterflow l/m

Simple health discovery

We have support for defining health / sensor discovery using YAML files so that you don't need to know how to write PHP.

Please note that DISPLAY-HINTS are disabled so ensure you use the correct divisor / multiplier if applicable.

All yaml files are located in includes/definitions/discovery/$os.yaml. Defining the information here is not always possible and is heavily reliant on vendors being sensible with the MIBs they generate. Only snmp walks are supported and you must provide a sane table that can be traversed and contains all of the data you need. We will use netbotz as an example here.

includes/definitions/discovery/netbotz.yaml

mib: NETBOTZV2-MIB
modules:
    sensors:
        airflow:
            options:
                skip_values_lt: 0
            data:
                -
                    oid: airFlowSensorTable
                    value: airFlowSensorValue
                    divisor: 10
                    num_oid: '.1.3.6.1.4.1.5528.100.4.1.5.1.2.{{ $index }}'
                    descr: '{{ $airFlowSensorLabel }}'
                    index: 'airFlowSensorValue.{{ $index }}'

At the top you can define one or more mibs to be used in the lookup of data:

mib: NETBOTZV2-MIB For use of multiple MIB files separate them with a colon: mib: NETBOTZV2-MIB:SECOND-MIB

For data: you have the following options:

The only sensor we have defined here is airflow. The available options are as follows:

  • oid (required): This is the name of the table you want to do the snmp walk on.
  • value (optional): This is the key within the table that contains the value. If not provided willuse oid
  • num_oid (required): This is the numerical OID that contains value. This should always include {{ $index }}. snmptranslate -On can help figure out the number. In case the index is a string, {{ $index_string }} can be used instead.
  • divisor (optional): This is the divisor to use against the returned value.
  • multiplier (optional): This is the multiplier to use against the returned value.
  • low_limit (optional): This is the critical low threshold that value should be (used in alerting). If an OID is specified then divisor / multiplier are used.
  • low_warn_limit (optional): This is the warning low threshold that value should be (used in alerting). If an OID is specified then divisor / multiplier are used.
  • warn_limit (optional): This is the warning high threshold that value should be (used in alerting). If an OID is specified then divisor / multiplier are used.
  • high_limit (optional): This is the critical high threshold that value should be (used in alerting). If an OID is specified then divisor / multiplier are used.
  • descr (required): The visible label for this sensor. It can be a key with in the table or a static string, optionally using {{ index }}.
  • group (optional): Groups sensors together under in the webui, displaying this text. Not specifying this will put the sensors in the default group.
  • index (optional): This is the index value we use to uniquely identify this sensor. {{ $index }} will be replaced by the index from the snmp walk.
  • skip_values (optional): This is an array of values we should skip over (see note below).
  • skip_value_lt (optional): If sensor value is less than this, skip the discovery.
  • skip_value_gt (optional): If sensor value is greater than this, skip the discovery.
  • entPhysicalIndex (optional): If the sensor belongs to a physical entity then you can specify the index here.
  • entPhysicalIndex_measured (optional): If the sensor belongs to a physical entity then you can specify the entity type here.
  • user_func (optional): You can provide a function name for the sensors value to be processed through (i.e. Convert fahrenheit to celsius use fahrenheit_to_celsius)

For options: you have the following available:

  • divisor: This is the divisor to use against the returned value.
  • multiplier: This is the multiplier to use against the returned value.
  • skip_values: This is an array of values we should skip over (see note below).
  • skip_value_lt: If sensor value is less than this, skip the discovery.
  • skip_value_gt: If sensor value is greater than this, skip the discovery.

Multiple variables can be used in the sensors definition. The syntax is {{ $variable }}. Any oid in the current table can be used, as well as pre_cached data. The index ($index) and the sub_indexes (in case the oid is indexed multiple times) are also available: if $index="1.20", then $subindex0="1" and $subindex1="20".

skip_values can also compare items within the OID table against values. The index of the sensor is used to retrieve the value from the OID, unless a target index is appended to the OID. Comparisons behave on a logical OR basis when chained, so only one of them needs to be matched for that particular sensor to be skipped during discovery. An example of this is below:

                    skip_values:
                    -
                      oid: sensUnit
                      op: '!='
                      value: 4
                    -
                      oid: sensConfig.0
                      op: '!='
                      value: 1

op can be any of the following operators :

=, !=, ==, !==, <=, >=, <, >, starts, ends, contains, regex, in_array, not_starts, not_ends, not_contains, not_regex, not_in_array, exists

Example:

                    skip_values:
                    -
                      oid: sensorName
                      op: 'not_in_array'
                      value: ['sensor1', 'sensor2']
                    skip_values:
                    -
                      oid: sensorOptionalOID
                      op: 'exists'
                      value: false

If you aren't able to use yaml to perform the sensor discovery, you will most likely need to use Advanced health discovery.

Advanced health discovery

If you can't use the yaml files as above, then you will need to create the discovery code in php.

The directory structure for sensor information is includes/discovery/sensors/$class/$os.inc.php. The format of all of the sensors follows the same code format which is to collect sensor information via SNMP and then call the discover_sensor() function; with the exception of state sensors which requires additional code. Sensor information is commonly found in an ENTITY mib supplied by device's vendor in the form of a table. Other mib tables may be used as well. Sensor information is first collected by includes/discovery/sensors/pre_cache/$os.inc.php. This program will pull in data from mib tables into a $pre_cache array that can then be used in includes/discovery/sensors/$class/$os.inc.php to extract specific values which are then passed to discover_sensor().

discover_sensor() Accepts the following arguments:

  • &$valid = This is always $valid['sensor'], do not pass any other values.
  • $class = Required. This is the sensor class from the table above (i.e humidity).
  • $device = Required. This is the $device array.
  • $oid = Required. This must be the numerical OID for where the data can be found, i.e .1.2.3.4.5.6.7.0
  • $index = Required. This must be unique for this sensor class, device and type. Typically it's the index from the table being walked or it could be the name of the OID if it's a single value.
  • $type = Required. This should be the OS name, i.e pulse.
  • $descr = Required. This is a descriptive value for the sensor. Some devices will provide names to use.
  • $divisor = Defaults to 1. This is used to divided the returned value.
  • $multiplier = Defaults to 1. This is used to multiply the returned value.
  • $low_limit = Defaults to null. Sets the low threshold limit for the sensor, used in alerting to report out range sensors.
  • $low_warn_limit = Defaults to null. Sets the low warning limit for the sensor, used in alerting to report near out of range sensors.
  • $warn_limit = Defaults to null. Sets the high warning limit for the sensor, used in alerting to report near out of range sensors.
  • $high_limit = Defaults to null. Sets the high limit for the sensor, used in alerting to report out range sensors.
  • $current = Defaults to null. Can be used to set the current value on discovery. Poller will update this on the next poll cycle anyway.
  • $poller_type = Defaults to snmp. Things like the unix-agent can set different values but for the most part this should be left as snmp.
  • $entPhysicalIndex = Defaults to null. Sets the entPhysicalIndex to be used to look up further hardware if available.
  • $entPhysicalIndex_measured = Defaults to null. Sets the type of entPhysicalIndex used, i.e ports.
  • $user_func = Defaults to null. You can provide a function name for the sensors value to be processed through (i.e. Convert fahrenheit to celsius use fahrenheit_to_celsius)
  • $group = Defaults to null. Groups sensors together under in the webui, displaying this text.

For the majority of devices, this is all that's required to add support for a sensor. Polling is done based on the data gathered using discover_sensor(). If custom polling is needed then the file format is similar to discovery: includes/polling/sensors/$class/$os.inc.php. Whilst it's possible to perform additional snmp queries within polling this should be avoided where possible. The value for the OID is already available as $sensor_value.

Graphing is performed automatically for sensors, no custom graphing is required or supported.

Adding a new sensor class

You will need to add code for your new sensor class in the following existing files:

  • app/Models/Sensor.php: add a free icon from Font Awesome in the $icons array.
  • doc/Developing/os/Health-Information.md: documentation for every sensor class is mandatory.
  • includes/discovery/sensors.inc.php: add the sensor class to the $run_sensors array.
  • includes/discovery/functions.inc.php: optional - if sensible low_limit and high_limit values are guessable when a SNMP-retrievable threshold is not available, add a case for the sensor class to the sensor_limit() and/or sensor_low_limit() functions.
  • LibreNMS/Util/ObjectCache.php: optional - choose menu grouping for the sensor class.
  • includes/html/pages/device/health.inc.php: add a dbFetchCell(), $datas[], and $type_text[] entry for the sensor class.
  • includes/html/pages/device/overview.inc.php: add require 'overview/sensors/$class.inc.php' in the desired order for the device overview page.
  • includes/html/pages/health.inc.php: add a $type_text[] entry for the sensor class.
  • resources/lang/en/sensors.php: add human-readable names and units for the sensor class in English, feel free to do so for other languages as well.

Create and populate new files for the sensor class in the following places:

  • includes/discovery/sensors/$class/: create the folder where advanced php-based discovery files are stored. Not used for yaml discovery. =======
  • includes/html/pages/device/health.inc.php: add a dbFetchCell(), $datas[], and $type_text[] entry for the sensor class.
  • includes/html/pages/device/overview.inc.php: add require 'overview/sensors/$class.inc.php' in the desired order for the device overview page.
  • includes/html/pages/health.inc.php: add a $type_text[] entry for the sensor class.
  • resources/lang/en/sensors.php: add human-readable names and units for the sensor class in English, feel free to do so for other languages as well.

Create and populate new files for the sensor class in the following places:

  • includes/discovery/sensors/$class/: create the folder where advanced php-based discovery files are stored. Not used for yaml discovery.
  • includes/html/graphs/device/$class.inc.php: define unit names used in RRDtool graphs.
  • includes/html/graphs/sensor/$class.inc.php: define various parameters for RRDtool graphs.
  • includes/html/pages/device/health/$class.inc.php
  • includes/html/pages/device/overview/sensors/$class.inc.php
  • includes/html/pages/health/$class.inc.php

Advanced health sensor example

This example shows how to build sensors using the advanced method. In this example we will be collecting optical power level (dBm) from Adva FSP150CC family MetroE devices. This example will assume an understanding of SNMP and MIBs.

First we setup includes/discovery/sensors/pre_cache/adva_fsp150.inc as shown below. The first line walks the cmEntityObject table to get information about the chassis and line cards. From this information we extract the model type which will identify which tables in the CM-Facility-Mib the ports are populated in. The program then reads the appropriate table into the $pre_cache array adva_fsp150_ports. This array will have OID indexies for each port, which we will use later to identify our sensor OIDs.

$pre_cache['adva_fsp150'] = snmpwalk_cache_multi_oid($device, 'cmEntityObjects', [], 'CM-ENTITY-MIB', null, '-OQUbs');
$neType = $pre_cache['adva_fsp150'][1]['neType'];

if ($neType == 'ccxg116pro') {
    $pre_cache['adva_fsp150_ports'] = snmpwalk_cache_multi_oid($device, 'cmEthernetTrafficPortTable', $pre_cache['adva_fsp150_ports'], 'CM-FACILITY-MIB', null, '-OQUbs');
} else {
    $pre_cache['adva_fsp150_ports'] = snmpwalk_cache_multi_oid($device, 'cmEthernetNetPortTable', $pre_cache['adva_fsp150_ports'], 'CM-FACILITY-MIB', null, '-OQUbs');
    $pre_cache['adva_fsp150_ports'] = snmpwalk_cache_multi_oid($device, 'cmEthernetAccPortTable', $pre_cache['adva_fsp150_ports'], 'CM-FACILITY-MIB', null, '-OQUbs');
}

Next we are going to build our sensor discovery code. These are optical readings, so the file will be created as the dBm sensor type in includes/discover/sensors/dbm/adva_fsp150.inc.php. Below is a snippet of the code:

foreach ($pre_cache['adva_fsp150_ports'] as $index => $entry) {
    if ($entry['cmEthernetTrafficPortMediaType'] == 'fiber') {
        //Discover received power level
        $oidRx = '.1.3.6.1.4.1.2544.1.12.5.1.21.1.34.' . $index . '.3';
        $oidTx = '.1.3.6.1.4.1.2544.1.12.5.1.21.1.33.' . $index . '.3';
        $currentRx = snmp_get($device, $oidRx, '-Oqv', 'CM-PERFORMANCE-MIB', '/opt/librenms/mibs/adva');
        $currentTx = snmp_get($device, $oidTx, '-Oqv', 'CM-PERFORMANCE-MIB', '/opt/librenms/mibs/adva');
        if ($currentRx != 0 || $currentTx != 0) {
            $entPhysicalIndex = $entry['cmEthernetTrafficPortIfIndex'];
            $entPhysicalIndex_measured = 'ports';
            $descrRx = dbFetchCell('SELECT `ifName` FROM `ports` WHERE `ifIndex`= ? AND `device_id` = ?', [$entry['cmEthernetTrafficPortIfIndex'], $device['device_id']]) . ' Rx Power';

            discover_sensor(
                $valid['sensor'],
                'dbm',
                $device,
                $oidRx,
                'cmEthernetTrafficPortStatsOPR.' . $index,
                'adva_fsp150',
                $descrRx,
                $divisor,
                $multiplier,
                null,
                null,
                null,
                null,
                $currentRx,
                'snmp',
                $entPhysicalIndex,
                $entPhysicalIndex_measured
            );

            $descrTx = dbFetchCell('SELECT `ifName` FROM `ports` WHERE `ifIndex`= ? AND `device_id` = ?', [$entry['cmEthernetTrafficPortIfIndex'], $device['device_id']]) . ' Tx Power';

            discover_sensor(
                $valid['sensor'],
                'dbm',
                $device,
                $oidTx,
                'cmEthernetTrafficPortStatsOPT.' . $index,
                'adva_fsp150',
                $descrTx,
                $divisor,
                $multiplier,
                null,
                null,
                null,
                null,
                $currentTx,
                'snmp',
                $entPhysicalIndex,
                $entPhysicalIndex_measured
            );
        }
    }
}

First the program will loop through each port's index value. In the case of Advas, the ports are names Ethernet 1-1-1-1, 1-1-1-2, etc, and they are indexed as oid.1.1.1.1, oid.1.1.1.2, etc in the mib.

Next the program checks which table the port exists in and that the connector type is 'fiber'. There are other port tables in the full code that were ommitted from the example for brevity. Copper media won't have optical readings, so if the media type isn't fiber we skip discovery for that port.

The next two lines build the OIDs for getting the optical receive and transmit values using the $index for the port. Using the OIDs the program gets the current receive and transmit values ($currentRx and $currentTx repectively) to verify the values are not 0. Not all SFPs collect digital optical monitoring (DOM) data, in the case of Adva the value of both transmit and recieve will be 0 if DOM is not available. While 0 is a valid value for optical power, its extremely unlikely that both will be 0 if DOM is present. If DOM is not available, then the program stops discovery for that port. Note that while this is the case with Adva, other vendors may differ in how they handle optics that do not supply DOM. Please check your vendor's mibs.

Next the program assigns the values of $entPhysicalIndex and $entPhysicalIndex_measured. In this case $entPhysicalIndex is set to the value of the cmEthernetTrafficPortIfIndex so that it is associated with port. This will also allow the sensor graphs to show up on the associated port's page in the GUI in addition to the Health page.

Following that the program uses a database call to get the description of the port which will be used as the title for the graph in the GUI.

Lastly the program calls discover_sensor() and passes the information collected in the previous steps. The null values are for low, low warning, high, and high warning values, which are not collected in the Adva's MIB.

You can manually run discovery to verify the code works by running ./discovery.php -h $device_id -m sensors. You can use -v to see what calls are being used during discovery and -d to see debug output. In the output under #### Load disco module sensors #### you can see a list of sensors types. If there is a + a sensor is added, if there is a - one was deleted, and a . means no change. If there is nothing next to the sensor type then the sensor was not discovered. There is is also information about changes to the database and RRD files at the bottom.

[[email protected] ~]$ ./discovery.php -h 2 -m sensors
LibreNMS Discovery
164.113.194.250 2 adva_fsp150

#### Load disco module core ####

>> Runtime for discovery module 'core': 0.0240 seconds with 66536 bytes
>> SNMP: [2/0.06s] MySQL: [3/0.00s] RRD: [0/0.00s]
#### Unload disco module core ####


#### Load disco module sensors ####
Pre-cache adva_fsp150:
 ENTITY-SENSOR: Caching OIDs: entPhysicalDescr entPhysicalName entPhySensorType entPhySensorScale entPhySensorPrecision entPhySensorValue entPhySensorOperStatus
Airflow:
Current: .
Charge:
Dbm: Adva FSP-150 dBm..
Fanspeed:
Frequency:
Humidity:
Load:
Power:
Power_consumed:
Power_factor:
Runtime:
Signal:
State:
Count:
Temperature: ..
Voltage: .
Snr:
Pressure:
Cooling:
Delay:
Quality_factor:
Chromatic_dispersion:
Ber:
Eer:
Waterflow:

>> Runtime for discovery module 'sensors': 3.9340 seconds with 190024 bytes
>> SNMP: [16/3.89s] MySQL: [36/0.03s] RRD: [0/0.00s]
#### Unload disco module sensors ####

Discovered in 5.521 seconds

SNMP [18/3.96s]: Get[8/0.81s] Getnext[0/0.00s] Walk[10/3.15s]
MySQL [41/0.03s]: Cell[10/0.01s] Row[-4/-0.00s] Rows[31/0.02s] Column[0/0.00s] Update[2/0.00s] Insert[2/0.00s] Delete[0/0.00s]
RRD [0/0.00s]: Update[0/0.00s] Create [0/0.00s] Other[0/0.00s]