
# SNMP Exporter Config Generator

This config generator uses NetSNMP to parse MIBs, and generates configs for the snmp_exporter using them.

## Building

Due to the dynamic dependency on NetSNMP, you must build the generator yourself.

```
# Debian-based distributions.
sudo apt-get install unzip build-essential libsnmp-dev p7zip-full # Debian-based distros
# Redhat-based distributions.
sudo yum install gcc gcc-g++ make net-snmp net-snmp-utils net-snmp-libs net-snmp-devel # RHEL-based distros

go get github.com/prometheus/snmp_exporter/generator
cd ${GOPATH-$HOME/go}/src/github.com/prometheus/snmp_exporter/generator
go build
make mibs
```

## Running

```sh
export MIBDIRS=mibs
./generator generate
```

The generator reads in from `generator.yml` and writes to `snmp.yml`.

Additional command are available for debugging, use the `help` command to see them.

## Docker Users

If you would like to run the generator in docker to generate your `snmp.yml` config run the following commands.

The Docker image expects a directory containing the `generator.yml` and a directory called `mibs` that contains all MIBs you wish to use.

This example will generate the example `snmp.yml` which is included in the top level of the snmp_exporter repo:
```sh
make mibs
docker build -t snmp-generator .
docker run -ti \
  -v "${PWD}:/opt/" \
  snmp-generator generate
```

## File Format

`generator.yml` provides a list of modules. The simplest module is just a name
and a set of OIDs to walk.

```yaml
modules:
  module_name:  # The module name. You can have as many modules as you want.
    walk:       # List of OIDs to walk. Can also be SNMP object names or specific instances.
      - 1.3.6.1.2.1.2              # Same as "interfaces"
      - sysUpTime                  # Same as "1.3.6.1.2.1.1.3"
      - 1.3.6.1.2.1.31.1.1.1.6.40  # Instance of "ifHCInOctets" with index "40"

    version: 2  # SNMP version to use. Defaults to 2.
                # 1 will use GETNEXT, 2 and 3 use GETBULK.
    max_repetitions: 25  # How many objects to request with GET/GETBULK, defaults to 25.
                         # May need to be reduced for buggy devices.
    retries: 3   # How many times to retry a failed request, defaults to 3.
    timeout: 5s  # Timeout for each individual SNMP request, defaults to 5s.

    auth:
      # Community string is used with SNMP v1 and v2. Defaults to "public".
      community: public

      # v3 has different and more complex settings.
      # Which are required depends on the security_level.
      # The equivalent options on NetSNMP commands like snmpbulkwalk
      # and snmpget are also listed. See snmpcmd(1).
      username: user  # Required, no default. -u option to NetSNMP.
      security_level: noAuthNoPriv  # Defaults to noAuthNoPriv. -l option to NetSNMP.
                                    # Can be noAuthNoPriv, authNoPriv or authPriv.
      password: pass  # Has no default. Also known as authKey, -A option to NetSNMP.
                      # Required if security_level is authNoPriv or authPriv.
      auth_protocol: MD5  # MD5 or SHA, defaults to MD5. -a option to NetSNMP.
                          # Used if security_level is authNoPriv or authPriv.
      priv_protocol: DES  # DES or AES, defaults to DES. -x option to NetSNMP.
                          # Used if security_level is authPriv.
      priv_password: otherPass # Has no default. Also known as privKey, -X option to NetSNMP.
                               # Required if security_level is authPriv.
      context_name: context # Has no default. -n option to NetSNMP.
                            # Required if context is configured on the device.

    lookups:  # Optional list of lookups to perform.
              # The default for `keep_source_indexes` is false. Indexes must be unique for this option to be used.

      # If the index of a table is bsnDot11EssIndex, usually that'd be the label
      # on the resulting metrics from that table. Instead, use the index to
      # lookup the bsnDot11EssSsid table entry and create a bsnDot11EssSsid label
      # with that value.
      - source_indexes: [bsnDot11EssIndex]
        lookup: bsnDot11EssSsid
        drop_source_indexes: false  # If true, delete source index labels for this lookup.
                                    # This avoids label clutter when the new index is unique.

     overrides: # Allows for per-module overrides of bits of MIBs
       metricName:
         ignore: true # Drops the metric from the output.
         regex_extracts:
           Temp: # A new metric will be created appending this to the metricName to become metricNameTemp.
             - regex: '(.*)' # Regex to extract a value from the returned SNMP walks's value.
               value: '$1' # The result will be parsed as a float64, defaults to $1.
           Status:
             - regex: '.*Example'
               value: '1' # The first entry whose regex matches and whose value parses wins.
             - regex: '.*'
               value: '0'
         type: DisplayString # Override the metric type, possible types are:
                             #   gauge:   An integer with type gauge.
                             #   counter: An integer with type counter.
                             #   OctetString: A bit string, rendered as 0xff34.
                             #   DateAndTime: An RFC 2579 DateAndTime byte sequence. If the device has no time zone data, UTC is used.
                             #   DisplayString: An ASCII or UTF-8 string.
                             #   PhysAddress48: A 48 bit MAC address, rendered as 00:01:02:03:04:ff.
                             #   Float: A 32 bit floating-point value with type gauge.
                             #   Double: A 64 bit floating-point value with type gauge.
                             #   InetAddressIPv4: An IPv4 address, rendered as 1.2.3.4.
                             #   InetAddressIPv6: An IPv6 address, rendered as 0102:0304:0506:0708:090A:0B0C:0D0E:0F10.
                             #   InetAddress: An InetAddress per RFC 4001. Must be preceded by an InetAddressType.
                             #   InetAddressMissingSize: An InetAddress that violates section 4.1 of RFC 4001 by
                             #       not having the size in the index. Must be preceded by an InetAddressType.
                             #   EnumAsInfo: An enum for which a single timeseries is created. Good for constant values.
                             #   EnumAsStateSet: An enum with a time series per state. Good for variable low-cardinality enums.
                             #   Bits: An RFC 2578 BITS construct, which produces a StateSet with a time series per bit.
```

### EnumAsInfo and EnumAsStateSet

SNMP contains the concept of integer indexed enumerations (enums). There are two ways
to represent these strings in Prometheus. They can be "info" metrics, or they can be
"state sets". SNMP does not specify which should be used, and it's up to the use case
of the data. Some users may also prefer the raw integer value, rather than the string.

In order to set enum integer to string mapping, you must use one of the two overrides.

`EnumAsInfo` should be used for properties that provide inventory-like data. For example
a device type, the name of a colour etc. It is important that this value is constant.

`EnumAsStateSet` should be used for things that represent state or that you might want
to alert on. For example the link state, is it up or down, is it in an error state,
whether a panel is open or closed etc. Please be careful to not use this for high
cardinality values as it will generate 1 time series per possible value.

## Where to get MIBs

Some of these are quite sluggish, so use wget to download.

Put the extracted mibs in a location NetSNMP can read them from. `$HOME/.snmp/mibs` is one option.

* Cisco: ftp://ftp.cisco.com/pub/mibs/v2/v2.tar.gz
* APC: https://download.schneider-electric.com/files?p_File_Name=powernet432.mib
* Servertech: ftp://ftp.servertech.com/Pub/SNMP/sentry3/Sentry3.mib
* Palo Alto PanOS 7.0 enterprise MIBs: https://www.paloaltonetworks.com/content/dam/pan/en_US/assets/zip/technical-documentation/snmp-mib-modules/PAN-MIB-MODULES-7.0.zip
* Arista Networks: https://www.arista.com/assets/data/docs/MIBS/ARISTA-ENTITY-SENSOR-MIB.txt
                   https://www.arista.com/assets/data/docs/MIBS/ARISTA-SW-IP-FORWARDING-MIB.txt
                   https://www.arista.com/assets/data/docs/MIBS/ARISTA-SMI-MIB.txt
* Synology: https://global.download.synology.com/download/Document/Software/DeveloperGuide/Firmware/DSM/All/enu/Synology_MIB_File.zip
* MikroTik: http://download2.mikrotik.com/Mikrotik.mib
* UCD-SNMP-MIB (Net-SNMP): http://www.net-snmp.org/docs/mibs/UCD-SNMP-MIB.txt
* Ubiquiti Networks: http://dl.ubnt-ut.com/snmp/UBNT-MIB
                     http://dl.ubnt-ut.com/snmp/UBNT-UniFi-MIB
                     https://dl.ubnt.com/firmwares/airos-ubnt-mib/ubnt-mib.zip

https://github.com/librenms/librenms/tree/master/mibs can also be a good source of MIBs.

http://oidref.com is recommended for browsing MIBs.
