rhaymo/opencensus-node-default-metrics

Node default metrics collected using opencensus

Default metrics for node.js using opencensus

Collect default nodejs metrics using opencensus framework. This module is inspired and based on the prom-client and node-prometheus-gc-stats package.

Install

Install with npm:

npm i opencensus-default-metrics --save

Install with yarn:

yarn add opencensus-default-metrics

Usage

See example folder for a sample usage. The library does not bundle any web framework. To expose the metrics you have to use the opencensus exporters.

Default metrics

There are some default metrics recommended by Prometheus itself. To collect these, call collectDefaultMetrics

NOTE: Some of the metrics, concerning File Descriptors and Memory, are only available on Linux.

In addition, some Node-specific metrics are included, such as event loop lag, active handles and Node.js version. See what metrics there are in lib/metrics.

collectDefaultMetrics takes 1 options object with 3 entries, a timeout for how often the probe should be fired, an optional prefix for metric names and an opencensus stats object to which metrics should be registered. By default probes are launched every 10 seconds, but this can be modified like this:

const client = require('opencensus-default-metrics');

const collectDefaultMetrics = client.collectDefaultMetrics;

// Probe every 5th second.
collectDefaultMetrics({ timeout: 5000 });

To register metrics to another stats instance, pass it in as stats:

const { globalStats } = require('@opencensus/core');
const client = require('opencensus-default-metrics');

const collectDefaultMetrics = client.collectDefaultMetrics;

collectDefaultMetrics({ stats: globalStats });

To prefix metric names with your own arbitrary string, pass in a prefix:

const client = require('opencensus-default-metrics');

const collectDefaultMetrics = client.collectDefaultMetrics;

// Probe every 5th second.
collectDefaultMetrics({ prefix: 'my_application_' });

You can get the full list of metrics by inspecting client.metricsList.

collectDefaultMetrics returns an identification when invoked, which is a reference to the Timer used to keep the probes going. This can be passed to clearInterval in order to stop all probes.

NOTE: Existing intervals are automatically cleared when calling collectDefaultMetrics.

const client = require('opencensus-default-metrics');

const collectDefaultMetrics = client.collectDefaultMetrics;

const interval = collectDefaultMetrics();

// ... some time later

clearInterval(interval);

NOTE: unref is called on the interval internally, so it will not keep your node process going indefinitely if it's the only thing keeping it from shutting down.

Stop polling default metrics

To stop collecting the default metrics, you have to call the function and pass it to clearInterval.

const client = require('opencensus-default-metrics');

clearInterval(client.collectDefaultMetrics());

// Clear the stats
client.stats.clear();