Prometheus SNMP Exporter

This is an exporter that exposes information gathered from SNMP for use by the Prometheus monitoring system.

There are two components. An exporter that does the actual scraping, and a generator (which depends on NetSNMP) that creates the configuration for use by the exporter.

Installation

Binaries can be downloaded from the Github releases page.

Usage

./snmp_exporter

Visit http://localhost:9116/snmp?target=1.2.3.4 where 1.2.3.4 is the IP of the SNMP device to get metrics from. You can also specify a module parameter, to choose which module to use from the config file.

Configuration

The snmp exporter reads from a snmp.yml config file by default. This file is not intended to be written by hand, rather use the generator to generate it for you.

The default snmp.yml covers a variety of common hardware for which MIBs are available to the public, walking them using SNMP v2 GETBULK.

You'll need to use the generator in all but the simplest of setups. It is needed to customize which objects are walked, use non-public MIBs or specify authentication parameters.

Prometheus Configuration

The snmp exporter needs to be passed the address as a parameter, this can be done with relabelling.

Example config:

scrape_configs:
  - job_name: 'snmp'
    static_configs:
      - targets:
        - 192.168.1.2  # SNMP device.
    metrics_path: /snmp
    params:
      module: [if_mib]
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_target
      - source_labels: [__param_target]
        target_label: instance
      - target_label: __address__
        replacement: 127.0.0.1:9116  # The SNMP exporter's real hostname:port.

This setup allows Prometheus to provide scheduling and service discovery, as unlike all other exporters running an exporter on the machine from which we are getting the metrics from is not possible.

Large counter value handling

In order to provide accurate counters for large Counter64 values, the exporter will automatically wrap the value every 2^53 to avoid 64-bit float rounding.