OpenCensus shim

OpenCensus shim allows existing OpenCensus instrumentation to report to OpenTelemetry. This allows you to incrementally migrate your existing OpenCensus instrumentation to OpenTelemetry. More details are available in the OpenCensus Compatibility Specification.

Installation

npm install --save @opentelemetry/shim-opencensus
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Tracing usage

Installing the shim's require-in-the-middle hook

This is the recommended way to use the shim for tracing.

This package provides a require-in-the-middle hook which replaces OpenCensus's CoreTracer class with a shim implementation that writes to the OpenTelemetry API. This will cause all usage of OpenCensus's tracing methods (in OpenCensus instrumentation or your own custom instrumentation) to be reported to OpenTelemetry.

There are two options for installing the hook:

1. Using Node's --require flag to load the register module:

   node --require @opentelemetry/shim-opencensus/register ./app.js
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2. Programmatically:

   // Early in your application startup
   require('@opentelemetry/shim-opencensus').installShim();
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   Note that this has to be run before any OpenCensus tracers have been created.

Replace OpenCensus tracer with the ShimTracer in your code

Alternatively, you can replace any usage of OpenCensus tracers in your code with the ShimTracer directly.

Before:

const tracing = require('@opencensus/nodejs');
const tracer = tracing.start({samplingRate: 1}).tracer;

// ...

tracer.startRootSpan({name: 'main'}, rootSpan => {
  rootSpan.end();
});
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After:

const { trace } = require('@opentelemetry/api');
const { ShimTracer } = require('@opentelemetry/shim-opencensus');
const tracer = new ShimTracer(trace.getTracer('my-module'));

// ...

tracer.startRootSpan({name: 'main'}, rootSpan => {
  rootSpan.end();
});
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Metrics usage

OpenCensus metrics can be collected and sent to an OpenTelemetry exporter by providing the OpenCensusMetricProducer to your MetricReader. For example, to export OpenCensus metrics through the OpenTelemetry Prometheus exporter:

new MeterProvider({
  readers: [
    new PrometheusExporter({
      metricProducers: [
        new OpenCensusMetricProducer({
          openCensusMetricProducerManager:
            oc.Metrics.getMetricProducerManager(),
        }),
      ],
    }),
  ],
});
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Example

See examples/opencensus-shim for a short example.

License

Apache 2.0 - See LICENSE for more information.

Useful links

• For more information on OpenTelemetry, visit: https://opentelemetry.io/
• For help or feedback on this project, join us in GitHub Discussions