@opentelemetry/context-async-hooks

OpenTelemetry async_hooks-based Context Managers

This package provides two ContextManager implementations built on APIs from Node.js's [async_hooks][async-hooks-doc] module. If you're looking for a ContextManager to use in browser environments, consider opentelemetry-context-zone or opentelemetry-context-zone-peer-dep.

See the definition of the ContextManager interface and the problem it solves.

API

Two ContextManager implementations are exported:

• AsyncLocalStorageContextManager, based on AsyncLocalStorage
• AsyncHooksContextManager, based on AsyncHook. This is deprecated and will be removed in v3 (planned for mid-2025. AsyncLocalStorage is simpler, faster, available in Node.js v14.8.0 and later, and avoids this possible DoS vulnerability.

Prior art

Context propagation is a big subject when talking about tracing in Node.js. If you want more information about it here are some resources:

• https://www.npmjs.com/package/continuation-local-storage (which was the old way of doing context propagation)
• Datadog's own implementation for their JavaScript tracer
• OpenTracing implementation
• Discussion about context propagation by the Node.js Diagnostics Working Group

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.