@danielkoehler/nodejs

OpenCensus for Node.js

OpenCensus Node.js is an implementation of OpenCensus, a toolkit for collecting application performance and behavior monitoring data.

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

Please join gitter for help or feedback on this project.

Installation

Install OpenCensus with:

npm install @opencensus/nodejs

Traces

Instrumenting an Application

OpenCensus for Node.js has automatic instrumentation for HTTP and HTTPS out of the box. This means that spans are automatically created for operations of those packages. To use it, simply start the tracing instance.

const tracing = require('@opencensus/nodejs');
tracing.start();

Similarly for Typescript:

import * as tracing from '@opencensus/nodejs';
tracing.start();

Manually Instrument an Application

In addition to automatic tracing, it is possible to manually create your own root and child spans.

const rootSpanOptions = { name: 'your root span' };
tracing.tracer.startRootSpan(rootSpanOptions, (rootSpan) => {

    // You can create as many child spans as needed
    childSpan = tracing.tracer.startChildSpan('name of your child span');
    // Do some operation...
    // Finish the child span at the end of it's operation
    childSpan.end();

    // Finish the root span at the end of the operation
    rootSpan.end();
});

Tracing Options

Tracing has many options available to choose from. At tracing.start(), you can set the following:

Options	Type	Description
bufferSize	number	The number of traces to be collected before exporting to a backend
bufferTimeout	number	Maximum time to wait before exporting to a backend
logger	Logger	A logger object
logLevel	number	Level of logger - 0: disable, 1: error, 2: warn, 3: info, 4: debug
samplingRate	number	Determines the span's sampling rate. Ranges from 0.0 to 1.0
propagation	Propagation	A propagation instance to use
maximumLabelValueSize	number	The maximum number of characters reported on a label value
plugin	PluginNames	A list of trace instrumentations plugins to load
exporter	Exporter	An exporter object

Plugins

OpenCensus can collect tracing data automatically using plugins. Users can also create and use their own plugins. Currently, OpenCensus supports automatic tracing for:

• HTTP
• HTTPS

Propagation

OpenCensus collects distributed tracing. It is able to do so by propagating span data through services. Currently, OpenCensus supports:

• B3 Propagation
• Stackdriver Propagation

Exporters

OpenCensus can export trace data to various backends. Currently, OpenCensus supports:

• Stackdriver
• Zipkin
• Z-Pages
• Jaeger

If no exporter is registered in the tracing instance, as default, a console log exporter is used.

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