feat(opentelemetry): expose OtlpExporter as public API

Exposes the internal OTLP exporter as OtlpExporter.make() to allow building
custom multi-endpoint tracers or composing multiple exporters.

Author: jonastemplestein

.changeset/export-otlp-exporter.md

@@ -0,0 +1,24 @@
+---
+"@effect/opentelemetry": minor
+---
+
+feat(OtlpExporter): expose internal OTLP exporter as public API
+
+The internal OTLP exporter is now available as `OtlpExporter.make()`. This allows building custom multi-endpoint tracers or composing multiple exporters without copying internal code.
+
+Example:
+```typescript
+import { OtlpExporter } from "@effect/opentelemetry"
+
+const exporter = yield* OtlpExporter.make({
+  url: "https://api.honeycomb.io/v1/traces",
+  headers: { "x-honeycomb-team": "api-key" },
+  label: "honeycomb",
+  exportInterval: "5 seconds",
+  maxBatchSize: 100,
+  body: (spans) => ({ resourceSpans: [{ scopeSpans: [{ spans }] }] }),
+  shutdownTimeout: "3 seconds"
+})
+
+exporter.push(spanData)
+```

packages/opentelemetry/src/OtlpExporter.ts

@@ -0,0 +1,117 @@
+/**
+ * OTLP Exporter
+ *
+ * A generic OTLP exporter that can be used to build custom tracers, metrics exporters,
+ * or loggers that send data to OTLP-compatible backends.
+ *
+ * This exporter handles:
+ * - Batching of data with configurable batch size
+ * - Automatic retry with backoff on transient errors
+ * - Rate limiting with 429 Retry-After header support
+ * - Graceful shutdown with timeout
+ * - Automatic disabling for 60 seconds on persistent failures
+ *
+ * @since 1.0.0
+ * @example
+ * ```typescript
+ * import { OtlpExporter } from "@effect/opentelemetry"
+ * import { BunHttpClient } from "@effect/platform-bun"
+ * import { Effect, Layer } from "effect"
+ *
+ * const program = Effect.gen(function*() {
+ *   const exporter = yield* OtlpExporter.make({
+ *     url: "https://api.honeycomb.io/v1/traces",
+ *     headers: { "x-honeycomb-team": "your-api-key" },
+ *     label: "honeycomb",
+ *     exportInterval: "5 seconds",
+ *     maxBatchSize: 100,
+ *     body: (spans) => ({ resourceSpans: [{ scopeSpans: [{ spans }] }] }),
+ *     shutdownTimeout: "3 seconds"
+ *   })
+ *
+ *   // Push data to be exported
+ *   exporter.push({ traceId: "...", spanId: "...", name: "my-span" })
+ * })
+ *
+ * program.pipe(
+ *   Effect.scoped,
+ *   Effect.provide(BunHttpClient.layer),
+ *   Effect.runPromise
+ * )
+ * ```
+ */
+import type * as Headers from "@effect/platform/Headers"
+import type * as HttpClient from "@effect/platform/HttpClient"
+import type * as Duration from "effect/Duration"
+import type * as Effect from "effect/Effect"
+import type * as Scope from "effect/Scope"
+import * as internal from "./internal/otlpExporter.js"
+
+/**
+ * @since 1.0.0
+ * @category Models
+ */
+export interface Exporter {
+  /**
+   * Push data to be exported. The data will be batched and sent according
+   * to the configured export interval and batch size.
+   */
+  readonly push: (data: unknown) => void
+}
+
+/**
+ * @since 1.0.0
+ * @category Models
+ */
+export interface MakeOptions {
+  /**
+   * The OTLP endpoint URL to send data to.
+   */
+  readonly url: string
+  /**
+   * Optional HTTP headers to include in requests (e.g., authentication).
+   */
+  readonly headers?: Headers.Input | undefined
+  /**
+   * A label for this exporter, used in log messages and User-Agent header.
+   */
+  readonly label: string
+  /**
+   * How often to flush the buffer and send data.
+   * @default "5 seconds"
+   */
+  readonly exportInterval: Duration.DurationInput
+  /**
+   * Maximum number of items to batch before triggering an immediate export.
+   * Set to "disabled" to only export on interval.
+   * @default 1000
+   */
+  readonly maxBatchSize: number | "disabled"
+  /**
+   * Function to transform buffered items into the request body.
+   * This allows customizing the OTLP payload format.
+   */
+  readonly body: (data: Array<unknown>) => unknown
+  /**
+   * Maximum time to wait for pending exports during shutdown.
+   * @default "3 seconds"
+   */
+  readonly shutdownTimeout: Duration.DurationInput
+}
+
+/**
+ * Create an OTLP exporter that batches and sends data to an OTLP-compatible endpoint.
+ *
+ * The exporter automatically handles:
+ * - Batching based on interval and max batch size
+ * - Retry with exponential backoff on transient errors
+ * - 429 rate limiting with Retry-After header support
+ * - Graceful shutdown ensuring pending data is flushed
+ * - Auto-disable for 60 seconds on persistent failures (logged via Effect.logDebug)
+ *
+ * @since 1.0.0
+ * @category Constructors
+ */
+export const make: (
+  options: MakeOptions
+) => Effect.Effect<Exporter, never, HttpClient.HttpClient | Scope.Scope> = internal.make as any

packages/opentelemetry/src/index.ts

@@ -18,6 +18,11 @@ export * as NodeSdk from "./NodeSdk.js"
  */
 export * as Otlp from "./Otlp.js"
 
+/**
+ * @since 1.0.0
+ */
+export * as OtlpExporter from "./OtlpExporter.js"
+
 /**
  * @since 1.0.0
  */