@zaplabs/opencensus-core

OpenCensus Core Node.js

OpenCensus for Node.js is an implementation of OpenCensus, a toolkit for collecting application performance and behavior monitoring data. It currently includes 3 apis: stats, tracing and tags.

The library is in alpha stage and the API is subject to change.

Installation

Install the opencensus-core package with NPM:

npm install @zaplabs/opencensus-core

Usage

Set up a new Stats manager instance.

To enable metrics, we’ll import a few items from OpenCensus Core package.

const { Stats, MeasureUnit, AggregationType } = require('@zaplabs/opencensus-core');

// Create the Stats manager
const stats = new Stats();

// The latency in milliseconds
const mLatencyMs = stats.createMeasureDouble(
  "repl/latency",
  MeasureUnit.MS,
  "The latency in milliseconds"
);

Create Views and Tags:

We now determine how our metrics will be organized by creating Views. We will also create the variable needed to add extra text meta-data to our metrics – methodTagKey, statusTagKey, and errorTagKey.

const methodTagKey = "method";
const statusTagKey = "status";
const errorTagKey = "error";

const latencyView = stats.createView(
  "demo/latency",
  mLatencyMs,
  AggregationType.DISTRIBUTION,
  [methodTagKey, statusTagKey, errorTagKey],
  "The distribution of the latencies",
  // Bucket Boundaries:
  // [>=0ms, >=25ms, >=50ms, >=75ms, >=100ms, >=200ms, >=400ms, >=600ms, >=800ms, >=1s, >=2s, >=4s, >=6s]
  [0, 25, 50, 75, 100, 200, 400, 600, 800, 1000, 2000, 4000, 6000]
);

Recording Metrics:

Now we will record the desired metrics. To do so, we will use stats.record() and pass in measurements.

const [_, startNanoseconds] = process.hrtime();
const tags = {method: "repl", status: "OK"};

stats.record({
  measure: mLatencyMs,
  tags,
  value: sinceInMilliseconds(startNanoseconds)
});


function sinceInMilliseconds(startNanoseconds) {
  const [_, endNanoseconds] = process.hrtime();
  return (endNanoseconds - startNanoseconds) / 1e6;
}

See Quickstart/Metrics for a full example of registering and collecting metrics.

Useful links

• For more information on OpenCensus, visit: https://opencensus.io/
• To checkout the OpenCensus for Node.js, visit: https://github.com/census-instrumentation/opencensus-node
• For help or feedback on this project, join us on gitter

LICENSE

Apache License 2.0

Changelog

0.0.7 - 2018-11-12

Contains API breaking changes for stats/metrics implementations

• The histogram bucket boundaries (BucketBoundaries) and values (Count and Sum) are no longer supported for negative values. The Record API drops the negative value and logs the warning. This could be a breaking change if you are recording negative value for any measure.
• Use setInterval to upload metrics to Stackdriver periodically.
• fix spanId format.