Fix Tracer.currentOtelSpan to work with OTLP module (#5890)

Co-authored-by: Claude <[email protected]>
Co-authored-by: Tim Smart <[email protected]>

Author: 3 people

.changeset/current-span-context.md

@@ -0,0 +1,9 @@
+---
+"@effect/opentelemetry": patch
+---
+
+Fix `Tracer.currentOtelSpan` to work with OTLP module
+
+`currentOtelSpan` now works with both the official OpenTelemetry SDK and the lightweight OTLP module. When using OTLP, it returns a wrapper that conforms to the OpenTelemetry Span interface.
+
+Closes #5889

packages/opentelemetry/src/Tracer.ts

@@ -30,6 +30,14 @@ export const makeExternalSpan: (
 ) => ExternalSpan = internal.makeExternalSpan
 
 /**
+ * Get the current OpenTelemetry span.
+ *
+ * Works with both the official OpenTelemetry API (via `Tracer.layer`, `NodeSdk.layer`, etc.)
+ * and the lightweight OTLP module (`OtlpTracer.layer`).
+ *
+ * When using OTLP, the returned span is a wrapper that conforms to the
+ * OpenTelemetry `Span` interface.
+ *
  * @since 1.0.0
  * @category accessors
  */

packages/opentelemetry/src/internal/tracer.ts

@@ -1,10 +1,11 @@
 import * as OtelApi from "@opentelemetry/api"
 import * as OtelSemConv from "@opentelemetry/semantic-conventions"
 import * as Cause from "effect/Cause"
+import type * as Clock from "effect/Clock"
 import * as Context from "effect/Context"
 import * as Effect from "effect/Effect"
-import type { Exit } from "effect/Exit"
-import { dual } from "effect/Function"
+import * as Exit from "effect/Exit"
+import { constTrue, dual } from "effect/Function"
 import * as Layer from "effect/Layer"
 import * as Option from "effect/Option"
 import * as EffectTracer from "effect/Tracer"
@@ -109,7 +110,7 @@ export class OtelSpan implements EffectTracer.Span {
     })))
   }
 
-  end(endTime: bigint, exit: Exit<unknown, unknown>) {
+  end(endTime: bigint, exit: Exit.Exit<unknown, unknown>) {
     const hrTime = nanosToHrTime(endTime)
     this.status = {
       _tag: "Ended",
@@ -237,15 +238,106 @@ export const makeExternalSpan = (options: {
   }
 }
 
+const makeOtelSpan = (span: EffectTracer.Span, clock: Clock.Clock): OtelApi.Span => {
+  const spanContext: OtelApi.SpanContext = {
+    traceId: span.traceId,
+    spanId: span.spanId,
+    traceFlags: span.sampled ? OtelApi.TraceFlags.SAMPLED : OtelApi.TraceFlags.NONE,
+    isRemote: false
+  }
+
+  let exit = Exit.void
+
+  const self: OtelApi.Span = {
+    spanContext: () => spanContext,
+    setAttribute(key, value) {
+      span.attribute(key, value)
+      return self
+    },
+    setAttributes(attributes) {
+      for (const [key, value] of Object.entries(attributes)) {
+        span.attribute(key, value)
+      }
+      return self
+    },
+    addEvent(name) {
+      let attributes: OtelApi.Attributes | undefined = undefined
+      let startTime: OtelApi.TimeInput | undefined = undefined
+      if (arguments.length === 3) {
+        attributes = arguments[1]
+        startTime = arguments[2]
+      } else {
+        startTime = arguments[1]
+      }
+      span.event(name, convertOtelTimeInput(startTime, clock), attributes)
+      return self
+    },
+    addLink(link) {
+      span.addLinks([{
+        _tag: "SpanLink",
+        span: makeExternalSpan(link.context),
+        attributes: link.attributes ?? {}
+      }])
+      return self
+    },
+    addLinks(links) {
+      span.addLinks(links.map((link) => ({
+        _tag: "SpanLink",
+        span: makeExternalSpan(link.context),
+        attributes: link.attributes ?? {}
+      })))
+      return self
+    },
+    setStatus(status) {
+      exit = OtelApi.SpanStatusCode.ERROR
+        ? Exit.die(status.message ?? "Unknown error")
+        : Exit.void
+      return self
+    },
+    updateName: () => self,
+    end(endTime) {
+      const time = convertOtelTimeInput(endTime, clock)
+      span.end(time, exit)
+      return self
+    },
+    isRecording: constTrue,
+    recordException(exception, timeInput) {
+      const time = convertOtelTimeInput(timeInput, clock)
+      const cause = Cause.fail(exception)
+      const error = Cause.prettyErrors(cause)[0]
+      span.event(error.message, time, {
+        "exception.type": error.name,
+        "exception.message": error.message,
+        "exception.stacktrace": error.stack ?? ""
+      })
+    }
+  }
+  return self
+}
+
+const bigint1e6 = BigInt(1_000_000)
+const bigint1e9 = BigInt(1_000_000_000)
+
+const convertOtelTimeInput = (input: OtelApi.TimeInput | undefined, clock: Clock.Clock): bigint => {
+  if (input === undefined) {
+    return clock.unsafeCurrentTimeNanos()
+  } else if (typeof input === "number") {
+    return BigInt(Math.round(input * 1_000_000))
+  } else if (input instanceof Date) {
+    return BigInt(input.getTime()) * bigint1e6
+  }
+  const [seconds, nanos] = input
+  return BigInt(seconds) * bigint1e9 + BigInt(nanos)
+}
+
 /** @internal */
-export const currentOtelSpan = Effect.flatMap(
-  Effect.currentSpan,
-  (span) => {
+export const currentOtelSpan: Effect.Effect<OtelApi.Span, Cause.NoSuchElementException> = Effect.clockWith((clock) =>
+  Effect.map(Effect.currentSpan, (span): OtelApi.Span => {
     if (OtelSpanTypeId in span) {
-      return Effect.succeed((span as OtelSpan).span)
+      return (span as OtelSpan).span
     }
-    return Effect.fail(new Cause.NoSuchElementException())
-  }
+    return makeOtelSpan(span, clock)
+  })
 )
 
 /** @internal */

packages/opentelemetry/test/Tracer.test.ts

@@ -1,10 +1,13 @@
 import * as NodeSdk from "@effect/opentelemetry/NodeSdk"
+import * as OtlpTracer from "@effect/opentelemetry/OtlpTracer"
 import * as Tracer from "@effect/opentelemetry/Tracer"
+import { HttpClient } from "@effect/platform"
 import { assert, describe, expect, it } from "@effect/vitest"
 import * as OtelApi from "@opentelemetry/api"
 import { AsyncHooksContextManager } from "@opentelemetry/context-async-hooks"
 import { InMemorySpanExporter, SimpleSpanProcessor } from "@opentelemetry/sdk-trace-base"
 import * as Effect from "effect/Effect"
+import * as Layer from "effect/Layer"
 import * as Runtime from "effect/Runtime"
 import { OtelSpan } from "../src/internal/tracer.js"
 
@@ -123,4 +126,38 @@ describe("Tracer", () => {
         })
       ))
   })
+
+  describe("OTLP tracer", () => {
+    const MockHttpClient = Layer.succeed(
+      HttpClient.HttpClient,
+      HttpClient.make(() => Effect.die("mock http client"))
+    )
+    const OtlpTracingLive = OtlpTracer.layer({
+      url: "http://localhost:4318/v1/traces",
+      resource: {
+        serviceName: "test-otlp"
+      }
+    }).pipe(Layer.provide(MockHttpClient))
+
+    it.effect("currentOtelSpan works with OTLP tracer", () =>
+      Effect.provide(
+        Effect.withSpan("ok")(
+          Effect.gen(function*() {
+            const span = yield* Effect.currentSpan
+            const otelSpan = yield* Tracer.currentOtelSpan
+            const spanContext = otelSpan.spanContext()
+            expect(spanContext.traceId).toBe(span.traceId)
+            expect(spanContext.spanId).toBe(span.spanId)
+            expect(spanContext.traceFlags).toBe(OtelApi.TraceFlags.SAMPLED)
+            expect(spanContext.isRemote).toBe(false)
+            expect(otelSpan.isRecording()).toBe(true)
+
+            // it should proxy attribute changes
+            otelSpan.setAttribute("key", "value")
+            expect(span.attributes.get("key")).toEqual("value")
+          })
+        ),
+        OtlpTracingLive
+      ))
+  })
 })