Instrument dd-trace-api (#5145)

* initial poc

* get the inject test working

* support object mapping for callback args

* start adding telemetry

* parity on sending and receiving sides

* initial dd-trace-api test

* rest of dd-trace-api testing

* quick test refactor

* support span context methods

* lint

* hoist counter tag

* add plugin test

* replace -> replaceAll

Author: bengl

.github/workflows/plugins.yml

@@ -317,6 +317,14 @@ jobs:
           suffix: plugins-${{ github.job }}
       - uses: codecov/codecov-action@v5
 
+  dd-trace-api:
+    runs-on: ubuntu-latest
+    env:
+      PLUGINS: dd-trace-api
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./.github/actions/plugins/test
+
   dns:
     runs-on: ubuntu-latest
     env:

packages/datadog-plugin-dd-trace-api/src/index.js

@@ -0,0 +1,120 @@
+'use strict'
+
+const Plugin = require('../../dd-trace/src/plugins/plugin')
+const telemetryMetrics = require('../../dd-trace/src/telemetry/metrics')
+const apiMetrics = telemetryMetrics.manager.namespace('tracers')
+
+// api ==> here
+const objectMap = new WeakMap()
+
+const injectionEnabledTag =
+  `injection_enabled:${process.env.DD_INJECTION_ENABLED ? 'yes' : 'no'}`
+
+module.exports = class DdTraceApiPlugin extends Plugin {
+  static get id () {
+    return 'dd-trace-api'
+  }
+
+  constructor (...args) {
+    super(...args)
+
+    const tracer = this._tracer
+
+    this.addSub('datadog-api:v1:tracerinit', ({ proxy }) => {
+      const proxyVal = proxy()
+      objectMap.set(proxyVal, tracer)
+      objectMap.set(proxyVal.appsec, tracer.appsec)
+      objectMap.set(proxyVal.dogstatsd, tracer.dogstatsd)
+    })
+
+    const handleEvent = (name) => {
+      const counter = apiMetrics.count('dd_trace_api.called', [
+        `name:${name.replaceAll(':', '.')}`,
+        'api_version:v1',
+        injectionEnabledTag
+      ])
+
+      // For v1, APIs are 1:1 with their internal equivalents, so we can just
+      // call the internal method directly. That's what we do here unless we
+      // want to override. As the API evolves, this may change.
+      this.addSub(`datadog-api:v1:${name}`, ({ self, args, ret, proxy, revProxy }) => {
+        counter.inc()
+
+        if (name.includes(':')) {
+          name = name.split(':').pop()
+        }
+
+        if (objectMap.has(self)) {
+          self = objectMap.get(self)
+        }
+
+        for (let i = 0; i < args.length; i++) {
+          if (objectMap.has(args[i])) {
+            args[i] = objectMap.get(args[i])
+          }
+          if (typeof args[i] === 'function') {
+            const orig = args[i]
+            args[i] = (...fnArgs) => {
+              for (let j = 0; j < fnArgs.length; j++) {
+                if (revProxy && revProxy[j]) {
+                  const proxyVal = revProxy[j]()
+                  objectMap.set(proxyVal, fnArgs[j])
+                  fnArgs[j] = proxyVal
+                }
+              }
+              // TODO do we need to apply(this, ...) here?
+              return orig(...fnArgs)
+            }
+          }
+        }
+
+        try {
+          ret.value = self[name](...args)
+          if (proxy) {
+            const proxyVal = proxy()
+            objectMap.set(proxyVal, ret.value)
+            ret.value = proxyVal
+          } else if (ret.value && typeof ret.value === 'object') {
+            throw new TypeError(`Objects need proxies when returned via API (${name})`)
+          }
+        } catch (e) {
+          ret.error = e
+        }
+      })
+    }
+
+    // handleEvent('configure')
+    handleEvent('startSpan')
+    handleEvent('wrap')
+    handleEvent('trace')
+    handleEvent('inject')
+    handleEvent('extract')
+    handleEvent('getRumData')
+    handleEvent('profilerStarted')
+    handleEvent('context:toTraceId')
+    handleEvent('context:toSpanId')
+    handleEvent('context:toTraceparent')
+    handleEvent('span:context')
+    handleEvent('span:setTag')
+    handleEvent('span:addTags')
+    handleEvent('span:finish')
+    handleEvent('span:addLink')
+    handleEvent('scope')
+    handleEvent('scope:activate')
+    handleEvent('scope:active')
+    handleEvent('scope:bind')
+    handleEvent('appsec:blockRequest')
+    handleEvent('appsec:isUserBlocked')
+    handleEvent('appsec:setUser')
+    handleEvent('appsec:trackCustomEvent')
+    handleEvent('appsec:trackUserLoginFailureEvent')
+    handleEvent('appsec:trackUserLoginSuccessEvent')
+    handleEvent('dogstatsd:decrement')
+    handleEvent('dogstatsd:distribution')
+    handleEvent('dogstatsd:flush')
+    handleEvent('dogstatsd:gauge')
+    handleEvent('dogstatsd:histogram')
+    handleEvent('dogstatsd:increment')
+    handleEvent('use')
+  }
+}