source: Developing/os/Health-Information.md
path: blob/master/doc/

#### 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_disperision           | ps/nm                       |
| cooling                         | W                           |
| count                           | #                           |
| current                         | A                           |
| dbm                             | dBm                         |
| delay                           | s                           |
| eer                             | eer                         |
| fanspeed                        | rpm                         |
| frequency                       | Hz                          |
| humidity                        | %                           |
| load                            | %                           |
| 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`

```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 `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
- `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. One example of this is:

```yaml
                    skip_values:
                    -
                      oid: sensUnit
                      op: '!='
                      value: 4
```

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 call the
`discover_sensor()` function - with the exception of state which
requires additional code.

`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](https://fontawesome.com/icons?d=gallery&m=free) 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/$class/`: create the folder where advanced php-based discovery files are stored. Not used for yaml discovery.
  - `includes/html/graphs/device/$class.inc.php`: define unit names used in RRDtool graphs.
  - `includes/html/graphs/sensor/$class.inc.php`: define various [parameters](https://oss.oetiker.ch/rrdtool/doc/rrdgraph_graph.en.html) for RRDtool graphs.
  - `includes/html/pages/device/health/$class.inc.php`
  - `includes/html/pages/device/overview/sensors/$class.inc.php`
  - `includes/html/pages/health/$class.inc.php`
