The Prometheus NATS Exporter

The Prometheus NATS Exporter consists of both a package and an application that exports NATS server metrics to Prometheus for monitoring.
The exporter aggregates metrics from the NATS server server monitoring endpoints you choose (varz, connz, subz, routez, healthz…) into a single Prometheus exporter endpoint.

For an alternative approach that uses a System account instead of HTTP monitoring endpoints, see also: NATS Surveyor

Build

make build

If you want to run tests, you can do this.

make test
make lint

# If you want to see the coverage locally, then run this.
# make test-cover

Run

Start the prometheus-nats-exporter executable, and poll the varz metrics endpoints of the NATS server located on localhost configured with a monitor port of 5555.

prometheus-nats-exporter -varz "http://localhost:5555"

To run with docker, you can use the following image:

docker run natsio/prometheus-nats-exporter:latest

Usage

prometheus-nats-exporter <flags> url
# ./prometheus-nats-exporter
Usage:  ./prometheus-nats-exporter <flags> url
  -D    Enable debug log level.
  -DV
        Enable debug and trace log levels.
  -V    Enable trace log level.
  -a string
        Network host to listen on. (default "0.0.0.0")
  -accountz
        Get accountz metrics and limits.      
  -accstatz
        Get accstatz metrics.
  -addr string
        Network host to listen on. (default "0.0.0.0")
  -connz
        Get connection metrics.
  -connz_detailed connz
        Get detailed connection metrics for each client. Enables flag connz implicitly.
  -gatewayz
        Get gateway metrics.
  -healthz
        Get health metrics.
  -healthz_js_enabled_only
        Get health metrics with js-enabled-only=true.
  -healthz_js_server_only
        Get health metrics with js-server-only=true.
  -http_pass string
        Set the password for HTTP scrapes. NATS bcrypt supported.
  -http_user string
        Enable basic auth and set user name for HTTP scrapes.
  -jsz string
        Select JetStream metrics to filter (e.g streams, accounts, consumers)
  -jsz_stream_meta_keys
        Select JetStream stream metadata to output (comma separated)
  -jsz_consumer_meta_keys
        Select JetStream consumer metadata to output (comma separated)
  -l string
        Log file name.
  -leafz
        Get leaf metrics.
  -log string
        Log file name.
  -p int
        Port to listen on. (default 7777)
  -path string
        URL path from which to serve scrapes. (default "/metrics")
  -port int
        Port to listen on. (default 7777)
  -prefix string
        Replace the default prefix for all the metrics.
  -r string
        Remote syslog address to write log statements.
  -remote_syslog string
        Write log statements to a remote syslog.
  -ri int
        Interval in seconds to retry NATS Server monitor URL. (default 30)
  -routez
        Get route metrics.
  -s    Write log statements to the syslog.
  -subz
        Get subscription metrics.
  -syslog
        Write log statements to the syslog.
  -tlscacert string
        Client certificate CA for verification (used with HTTPS).
  -tlscert string
        Server certificate file (Enables HTTPS).
  -tlskey string
        Private key for server certificate (used with HTTPS).
  -use_internal_server_id
        Enables using ServerID from /varz
  -use_internal_server_name
        Enables using ServerName from /varz
  -varz
        Get general metrics.
  -version
        Show exporter version and exit.

The URL parameter

The url parameter is a standard url. Both http and https (when TLS is configured) is supported.

e.g. http://denver1.foobar.com:8222

Monitoring

The NATS Prometheus exporter exposes metrics through an HTTP interface, and will default to: http://0.0.0.0:7777/metrics.

When --http_user and --http_pass is used, you will need to set the username password in prometheus. See basic_auth in the prometheus configuration documentation. If using a bcrypted password use a very low cost as scrapes occur frequently.

It will return output that is readable by Prometheus.

The returned data looks like this:

# HELP gnatsd_varz_in_bytes in_bytes
# TYPE gnatsd_varz_in_bytes gauge
gnatsd_varz_in_bytes{server_id="http://localhost:8222"} 0
# HELP gnatsd_varz_in_msgs in_msgs
# TYPE gnatsd_varz_in_msgs gauge
gnatsd_varz_in_msgs{server_id="http://localhost:8222"} 0
# HELP gnatsd_varz_max_connections max_connections
# TYPE gnatsd_varz_max_connections gauge
gnatsd_varz_max_connections{server_id="http://localhost:8222"} 65536

The NATS Prometheus Exporter API

The NATS prometheus exporter also provides a simple and easy to use API that allows it to run embedded in your code.

Import the exporter package

    // import the API like this
    import (
      "github.com/nats-io/prometheus-nats-exporter/exporter"
    )

API Usage

In just a few lines of code, configure and launch an instance of the exporter.

 // Get the default options, and set what you need to.  The listen address and port
 // is how prometheus can poll for collected data.
 opts := exporter.GetDefaultExporterOptions()
 opts.ListenAddress = "localhost"
 opts.ListenPort = 8888
 opts.GetVarz = true
 opts.NATSServerURL = "http://localhost:8222"

 // create an exporter instance, ready to be launched.
 exp := exporter.NewExporter(opts)

 // start collecting data
 exp.Start()

 // when done, simply call Stop()
 exp.Stop()

 // For convenience, you can block until the exporter is stopped
 exp.WaitUntilDone()

Monitoring Walkthrough

For additional information, refer to the walkthrough of monitoring NATS with Prometheus and Grafana.