prometheus-nagios-plugin-exporter

Nagios-Plugin exporter

The nagios-plugin exporter provides Prometheus-compatible metrics using Nagios/Monitoring plugins.

Running this software

From binaries

[Build](#Building the software) the exporter

Then:

./prometheus-nagios-plugin-exporter <flags>

Checking the results

Visiting http://localhost:9665/probe?http_host=google.com&module=http will return metrics for a nagios-plugin probe named htt against google.com. The nagios_plugin_probe_success metric indicates if the probe succeeded.

Metrics concerning the operation of the exporter itself are available at the endpoint http://localhost:9665/metrics.

Debugging probe requests

Adding a debug=true parameter to the probe endpoint will return debug information for that probe, assuming, the feature has been enabled. By default it not active for security reasons, but can be enabled using the --web.debug commandline argument.

TLS and basic authentication

The Nagios-Plugin Exporter supports TLS and basic authentication. This enables better control of the various HTTP endpoints.

To use TLS and/or basic authentication, you need to pass a configuration file using the --web.config.file parameter. The format of the file is described in the exporter-toolkit repository.

Note that the TLS and basic authentication settings affect all HTTP endpoints: /metrics for scraping, /probe for probing, and the web UI.

Building the software

Local Build

make

Configuration

Nagios-Plugin exporter is configured via a configuration file and command-line flags (such as what configuration file to load, what port to listen on, and the logging format and level).

Nagios-Plugin exporter can reload its configuration file at runtime. If the new configuration is not well-formed, the changes will not be applied. A configuration reload is triggered by sending a SIGHUP to the Nagios-Plugin exporter process or by sending a HTTP POST request to the /-/reload endpoint.

To view all available command-line flags, run ./prometheus-nagios-plugin-exporter -h.

To specify which configuration file to load, use the --config.file flag.

Additionally, an example configuration is also available.

The exporter itself does not perform any monitoring, but instead calls executables following the Nagios Plugin conventions. The monitoring scope of this exporte is therefor limited to the available plugin executables.

The timeout of each probe is automatically determined from the scrape_timeout in the Prometheus config, slightly reduced to allow for network delays. This can be further limited by the timeout in the Nagios-Plugin exporter config file. If neither is specified, it defaults to 120 seconds.

Prometheus Configuration

Nagios-plugin exporter implements the multi-target exporter pattern, so we advice to read the guide Understanding and using the multi-target exporter pattern to get the general idea about the configuration.

Most Nagios plugins require some kind of target information, which can be done with relabelling.

Example config:

scrape_configs:
  - job_name: 'nagios_plugin'
    metrics_path: /probe
    params:
      module: [http]  # Using the check_http plugin
    static_configs:
      - targets:
        - http://prometheus.io    # Target to probe with http.
        - https://prometheus.io   # Target to probe with https.
        - http://example.com:8080 # Target to probe with http on port 8080.
    relabel_configs:
      - source_labels: [__address__]
        target_label: __param_http_host
      - source_labels: [__param_http_host]
        target_label: instance
      - target_label: __address__
        replacement: 127.0.0.1:9665  # The nagios_plugin exporter's real hostname:port.
  - job_name: 'nagios_plugin_exporter'  # collect nagios_plugin exporter's operational metrics.
    static_configs:
      - targets: ['127.0.0.1:9665']

Permissions

Given that the Nagios-plugin exporter simple executes scripts, special adjustments and preparations must be on that front (e.g. ensuring the net_raw capability is set on the check_icmp nagios plugin)

If a Nagios plugin requires elevated privileges, the only way to ensure proper execution, is to run the exporter with elevated privileges as well.