OpenTelemetry Baggage Span Processor for Node.js

The BaggageSpanProcessor reads entries stored in Baggage from the parent context and adds the baggage entries' keys and values to the span as attributes on span start.

Add this span processor to a tracer provider.

Keys and values added to Baggage will appear on subsequent child spans for a trace within this service and be propagated to external services in accordance with any configured propagation formats configured. If the external services also have a Baggage span processor, the keys and values will appear in those child spans as well.

⚠ Warning ⚠️

Do not put sensitive information in Baggage.

To repeat: a consequence of adding data to Baggage is that the keys and values will appear in all outgoing HTTP headers from the application.

Compatible with OpenTelemetry JS API and SDK 1.0+.

Installation

npm install --save @opentelemetry/baggage-span-processor

Usage

Add to the span processors that copies all baggage entries during configuration:

import { NodeSDK, tracing } from '@opentelemetry/sdk-node';
import { ALLOW_ALL_BAGGAGE_KEYS, BaggageSpanProcessor } from '@opentelemetry/baggage-span-processor';

const spanProcessors = [
  new tracing.SimpleSpanProcessor(
    new tracing.ConsoleSpanExporter()),
  new BaggageSpanProcessor(ALLOW_ALL_BAGGAGE_KEYS)];

const sdk = new NodeSDK({
  serviceName: "example-service",
  spanProcessors
});

sdk.start();

Alternatively, you can provide a custom baggage key predicate to select which baggage keys you want to copy.

For example, to only copy baggage entries that start with my-key:

new BaggageSpanProcessor((baggageKey: string) => key.startsWith('my-key'))

For example, to only copy baggage entries that matches the regex ^key.+:

const regex = new RegExp("^key.+")
new BaggageSpanProcessor((baggageKey: string) => regex.test(baggageKey))

Useful links

For more information on OpenTelemetry, visit: https://opentelemetry.io/
For more about OpenTelemetry JavaScript: https://github.com/open-telemetry/opentelemetry-js
For help or feedback on this project, join us in GitHub Discussions

License

APACHE 2.0 - See LICENSE for more information.