traceparent

This is a basic implementation of the traceparent header part of the W3C trace context spec.

Installation

npm install traceparent

Example Usage

const crypto = require('crypto')
const TraceParent = require('traceparent')

const version = Buffer.alloc(1).toString('hex')
const traceId = crypto.randomBytes(16).toString('hex')
const id = crypto.randomBytes(8).toString('hex')
const flags = '01'

const header = `${version}-${traceId}-${id}-${flags}`

const parent = TraceParent.fromString(header)

API

new TraceParent(buffer)

Construct a new TraceParent instance from an existing buffer. The contents are binary data that corresponds to the structure of the W3C traceparent header format, with separators removed.

TraceParent.fromString(header)

Reconstruct a TraceParent instance from a formatted W3C traceparent header string.

TraceParent.startOrResume(parent, settings)

Resume from a parent context, if given, or start a new context. Accepts another TraceParent instance, a W3C traceparent header string, or a Span or Transaction instance from elastic-apm-node.

Requires a settings object with a transactionSampleRate value from 0.0 to 1.0 to generate a sampling decision for the context. This will only be applied when starting a new context. When continuing an existing context, the sampling decision will be propagated into all child contexts.

traceParent.recorded

Returns true if this TraceParent is sampled.

traceParent.traceId

The traceId property will propagate through all children in the tree to link them all together.

traceParent.id

The id property is used to uniquely identify a given TraceParent instance within the tree.

traceParent.parentId

The parentId property links this context to its direct parent in the tree.

traceParent.flags

The flags property is used to store metadata such as the sampling decision.

traceParent.version

The version property corresponds to the version segment of the W3C traceparent header.

traceParent.child()

Create a new TraceParent instance that is a child of this one.

traceParent.toString()

Formats the TraceParent instance as a W3C traceparent header.

traceParent.ensureParentId()

Return the parent ID, if there is none, generate one. This is useful in browser instrumentation to produce a starting span around a browser request which was not instrumented prior to page load.

License

MIT