@opentelemetry/scope-async-hooks

OpenTelemetry AsyncHooks-based Scope Manager

This package provides async-hooks based scope manager which is used internally by OpenTelemetry plugins to propagate specific scope between function calls and async operations. It only targets NodeJS since async-hooks is only available there.

What is a ScopeManager ?

The definition and why they exist is available on the readme of the scope-base package.

Implementation in NodeJS

NodeJS has a specific API to track async scope: async-hooks, it allows to track creation of new async operation and their respective parent. This package only handle storing a specific object for a given async hooks context.

Limitations

Even if the API is native to NodeJS, it doesn't cover all possible cases of scope propagation but there is a big effort from the NodeJS team to fix those. That's why we generally advise to be on the latest LTS to benefit from performance and bug fixes.

There are known modules that break scope propagation (some of them are listed there), so it's possible that the scope manager doesn't work with them.

Prior arts

Context propagation is a big subject when talking about tracing in NodeJS, if you want more informations about that 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: here
• OpenTracing implementation: here
• Discussion about context propagation by the NodeJS diagnostics working group: here

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 on gitter

License

Apache 2.0 - See LICENSE for more information.

Changelog

0.2.0

Released 2019-11-04

:rocket: (Enhancement)

• opentelemetry-shim-opentracing, opentelemetry-tracing, opentelemetry-types
  • #449 fix: allow recording links only at Span creation time
• opentelemetry-core, opentelemetry-node, opentelemetry-tracing, opentelemetry-types
  • #454 fix(span): rename span recording flag
• opentelemetry-metrics
  • #475 add shutdown method on MetricExporter interface
• opentelemetry-plugin-document-load
  • #469 chore: fixing problem with load event and performance for loadend
• opentelemetry-core, opentelemetry-plugin-document-load, opentelemetry-tracing, opentelemetry-web
  • #466 chore: fixing coverage for karma using istanbul

:bug: (Bug Fix)

• opentelemetry-tracing
  • #444 fix: batchSpanProcessor test failing intermittently
• opentelemetry-core
  • #472 fix(core): add missing semver dependency

:books: (Refine Doc)

• #462 chore: update README
• #460 chore: move members list out of community repo
• #445 chore: update CONTRIBUTING.md
• #459 chore: update API docs

:sparkles: (Feature)

• opentelemetry-metrics, opentelemetry-types
  • #437 feat(metrics): add registerMetric and getMetrics
• opentelemetry-metrics
  • #468 feat: validate metric names
• opentelemetry-plugin-postgres
  • #417 feature(plugin): implement postgres plugin
• opentelemetry-core, opentelemetry-types
  • #451 feat: add IsRemote field to SpanContext, set by propagators
• opentelemetry-core, opentelemetry-plugin-document-load, opentelemetry-tracing, opentelemetry-types, opentelemetry-web
  • #433 feat(plugin-document-load): new plugin for document load for web tracer