add synthetics integration

src/constants.js

@@ -2,5 +2,6 @@
 
 module.exports = {
   SAMPLE_RATE_METRIC_KEY: '_sample_rate',
-  SAMPLING_PRIORITY_KEY: '_sampling_priority_v1'
+  SAMPLING_PRIORITY_KEY: '_sampling_priority_v1',
+  ORIGIN_KEY: '_dd.origin'
 }

src/format.js

@@ -5,6 +5,7 @@ const constants = require('./constants')
 const log = require('./log')
 
 const SAMPLING_PRIORITY_KEY = constants.SAMPLING_PRIORITY_KEY
+const ORIGIN_KEY = constants.ORIGIN_KEY
 
 const map = {
   'service.name': 'service',
@@ -40,6 +41,7 @@ function formatSpan (span) {
 }
 
 function extractTags (trace, span) {
+  const origin = span.context()._trace.origin
   const tags = span.context()._tags
 
   Object.keys(tags).forEach(tag => {
@@ -62,6 +64,10 @@ function extractTags (trace, span) {
         addTag(trace.meta, tag, tags[tag])
     }
   })
+
+  if (origin) {
+    addTag(trace.meta, ORIGIN_KEY, origin)
+  }
 }
 
 function extractError (trace, span) {

src/opentracing/propagation/text_map.js

@@ -7,16 +7,18 @@ const log = require('../../log')
 
 const traceKey = 'x-datadog-trace-id'
 const spanKey = 'x-datadog-parent-id'
+const originKey = 'x-datadog-origin'
 const samplingKey = 'x-datadog-sampling-priority'
 const baggagePrefix = 'ot-baggage-'
 const baggageExpr = new RegExp(`^${baggagePrefix}(.+)$`)
-const logKeys = [traceKey, spanKey, samplingKey]
+const logKeys = [traceKey, spanKey, samplingKey, originKey]
 
 class TextMapPropagator {
   inject (spanContext, carrier) {
     carrier[traceKey] = spanContext.toTraceId()
     carrier[spanKey] = spanContext.toSpanId()
 
+    this._injectOrigin(spanContext, carrier)
     this._injectSamplingPriority(spanContext, carrier)
     this._injectBaggageItems(spanContext, carrier)
 
@@ -33,6 +35,7 @@ class TextMapPropagator {
       spanId: new platform.Uint64BE(carrier[spanKey], 10)
     })
 
+    this._extractOrigin(carrier, spanContext)
     this._extractBaggageItems(carrier, spanContext)
     this._extractSamplingPriority(carrier, spanContext)
 
@@ -41,6 +44,14 @@ class TextMapPropagator {
     return spanContext
   }
 
+  _injectOrigin (spanContext, carrier) {
+    const origin = spanContext._trace.origin
+
+    if (origin) {
+      carrier[originKey] = origin
+    }
+  }
+
   _injectSamplingPriority (spanContext, carrier) {
     const priority = spanContext._sampling.priority
 
@@ -55,6 +66,14 @@ class TextMapPropagator {
     })
   }
 
+  _extractOrigin (carrier, spanContext) {
+    const origin = carrier[originKey]
+
+    if (typeof carrier[originKey] === 'string') {
+      spanContext._trace.origin = origin
+    }
+  }
+
   _extractBaggageItems (carrier, spanContext) {
     Object.keys(carrier).forEach(key => {
       const match = key.match(baggageExpr)

src/opentracing/span.js

@@ -52,14 +52,21 @@ class DatadogSpan extends Span {
     let spanContext
 
     if (parent) {
+      const trace = parent._trace
+      const finished = trace.started.length === trace.finished.length
+
       spanContext = new SpanContext({
         traceId: parent._traceId,
         spanId: platform.id(),
         parentId: parent._spanId,
         sampled: parent._sampled,
         sampling: parent._sampling,
         baggageItems: parent._baggageItems,
-        trace: parent._trace.started.length !== parent._trace.finished.length ? parent._trace : null
+        trace: {
+          started: finished ? [] : trace.started,
+          finished: finished ? [] : trace.finished,
+          origin: trace.origin
+        }
       })
     } else {
       const spanId = platform.id()

test/format.spec.js

@@ -4,6 +4,7 @@ const Int64BE = require('int64-buffer').Int64BE
 const constants = require('../src/constants')
 
 const SAMPLING_PRIORITY_KEY = constants.SAMPLING_PRIORITY_KEY
+const ORIGIN_KEY = constants.ORIGIN_KEY
 
 const id = new Int64BE(0x02345678, 0x12345678)
 
@@ -21,6 +22,7 @@ describe('format', () => {
       _tags: {},
       _metrics: {},
       _sampling: {},
+      _trace: {},
       _name: 'operation'
     }
 
@@ -101,6 +103,14 @@ describe('format', () => {
       expect(trace.meta['error.stack']).to.equal(span._error.stack)
     })
 
+    it('should extract the origin', () => {
+      spanContext._trace.origin = 'synthetics'
+
+      trace = format(span)
+
+      expect(trace.meta[ORIGIN_KEY]).to.equal('synthetics')
+    })
+
     describe('when there is an `error` tag ', () => {
       it('should set the error flag when error tag is true', () => {
         spanContext._tags['error'] = true

test/opentracing/propagation/text_map.spec.js

@@ -74,6 +74,21 @@ describe('TextMapPropagator', () => {
 
       expect(carrier).to.have.property('x-datadog-sampling-priority', '0')
     })
+
+    it('should inject the origin', () => {
+      const carrier = {}
+      const spanContext = new SpanContext({
+        traceId: new platform.Uint64BE(0, 123),
+        spanId: new platform.Uint64BE(-456),
+        trace: {
+          origin: 'synthetics'
+        }
+      })
+
+      propagator.inject(spanContext, carrier)
+
+      expect(carrier).to.have.property('x-datadog-origin', 'synthetics')
+    })
   })
 
   describe('extract', () => {
@@ -109,5 +124,13 @@ describe('TextMapPropagator', () => {
         baggageItems
       }))
     })
+
+    it('should extract the origin', () => {
+      textMap['x-datadog-origin'] = 'synthetics'
+      const carrier = textMap
+      const spanContext = propagator.extract(carrier)
+
+      expect(spanContext._trace).to.have.property('origin', 'synthetics')
+    })
   })
 })

test/opentracing/span.spec.js

@@ -60,7 +60,8 @@ describe('Span', () => {
       _baggageItems: { foo: 'bar' },
       _trace: {
         started: ['span'],
-        finished: []
+        finished: [],
+        origin: 'synthetics'
       }
     }
 
@@ -70,6 +71,7 @@ describe('Span', () => {
     expect(span.context()._parentId).to.deep.equal(new Uint64BE(456, 456))
     expect(span.context()._baggageItems).to.deep.equal({ foo: 'bar' })
     expect(span.context()._trace.started).to.deep.equal(['span', span])
+    expect(span.context()._trace.origin).to.equal('synthetics')
   })
 
   it('should start a new trace if the parent trace is finished', () => {
@@ -80,13 +82,15 @@ describe('Span', () => {
       _baggageItems: { foo: 'bar' },
       _trace: {
         started: ['span'],
-        finished: ['span']
+        finished: ['span'],
+        origin: 'synthetics'
       }
     }
 
     span = new Span(tracer, recorder, sampler, prioritySampler, { operationName: 'operation', parent })
 
     expect(span.context()._trace.started).to.deep.equal([span])
+    expect(span.context()._trace.origin).to.equal('synthetics')
   })
 
   it('should set the sample rate metric from the sampler', () => {