feat: introduce internal exporter http client

packages/opentelemetry-core/package.json

@@ -17,7 +17,7 @@
     "prepublishOnly": "npm run compile",
     "compile": "tsc --build tsconfig.json tsconfig.esm.json tsconfig.esnext.json",
     "clean": "tsc --build --clean tsconfig.json tsconfig.esm.json tsconfig.esnext.json",
-    "test": "nyc ts-mocha -p tsconfig.json test/**/*.test.ts --exclude 'test/platform/browser/**/*.ts'",
+    "test": "nyc ts-mocha -p tsconfig.json 'test/**/*.test.ts' --exclude 'test/platform/browser/**/*.ts'",
     "test:browser": "nyc karma start --single-run",
     "tdd": "npm run tdd:node",
     "tdd:node": "npm run test -- --watch-extensions ts --watch",

packages/opentelemetry-core/src/index.ts

@@ -24,7 +24,15 @@ export * from './common/types';
 export * from './ExportResult';
 export * from './version';
 export * as baggageUtils from './baggage/utils';
-export * from './platform';
+export {
+  SDK_INFO,
+  _globalThis,
+  getEnv,
+  hexToBase64,
+  otperformance,
+  unrefTimer,
+  RandomIdGenerator,
+} from './platform';
 export * from './propagation/composite';
 export * from './trace/W3CTraceContextPropagator';
 export * from './trace/IdGenerator';
@@ -42,7 +50,4 @@ export * from './utils/url';
 export * from './utils/wrap';
 export * from './utils/callback';
 export * from './version';
-import { _export } from './internal/exporter';
-export const internal = {
-  _export,
-};
+export * as internal from './internal';

packages/opentelemetry-core/src/internal/http-client.ts

@@ -0,0 +1,105 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+export interface RequestInit {
+  /**
+   * Defaults to "POST". Some http clients may not support methods orther than "POST", like 'sendBeacon'.
+   */
+  method?: string;
+  /**
+   * Content type of the payload. Would be appended to request headers if the http client supports it.
+   */
+  contentType?: string;
+  /**
+   * Request headers.
+   */
+  headers?: Record<string, string>;
+  /**
+   * Suggestive option, this may not be supported by every http client. After the specified milliseconds the request should timeout.
+   */
+  timeoutMs?: number;
+}
+
+export class RetriableError extends Error {
+  override name = 'RetriableError';
+  /**
+   * @param retryAfterMillis a non-negative number indicating the milliseconds to delay after the response is received.
+   *                         If it is -1, it indicates delaying with exponential backoff.
+   * @param cause the original error.
+   */
+  constructor(public retryAfterMillis: number, public cause?: Error) {
+    super(cause?.message);
+  }
+}
+
+export class HttpClientError extends Error {
+  override name = 'HttpClientError';
+  constructor(
+    public statusMessage?: string,
+    public statusCode?: number,
+    public payload?: unknown
+  ) {
+    super(statusMessage);
+  }
+}
+
+export function isRetriableError(error: unknown): error is RetriableError {
+  // eslint-disable-next-line @typescript-eslint/no-explicit-any
+  return (
+    error != null &&
+    typeof (error as RetriableError).retryAfterMillis === 'number'
+  );
+}
+
+const RETRIABLE_STATUS_CODES = [429, 502, 503, 504];
+export function isRetriableStatusCode(status?: number): boolean {
+  return status != null && RETRIABLE_STATUS_CODES.includes(status);
+}
+
+export function parseRetryAfterToMills(retryAfter?: string | null): number {
+  if (retryAfter == null) {
+    return -1;
+  }
+  const seconds = Number.parseInt(retryAfter, 10);
+  if (Number.isInteger(seconds)) {
+    return seconds > 0 ? seconds * 1000 : -1;
+  }
+  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Retry-After#directives
+  const delay = new Date(retryAfter).getTime() - Date.now();
+  if (delay >= 0) {
+    return delay * 1000;
+  }
+  return 0;
+}
+
+export type BufferLike = Uint8Array | string;
+
+export type HttpClient =
+  | 'XMLHttpReuqest'
+  | 'fetch'
+  | 'node:http'
+  | 'sendBeacon';
+
+/**
+ * Maximum compatible http request function that can be built on top of various http client ({@link HttpClient}).
+ * The returned promise can be rejected by {@link RetriableError} and the initiator should try to retry the request
+ * after backoffMs.
+ */
+export type RequestFunction = (
+  url: string,
+  payload: BufferLike,
+  requestInit?: RequestInit
+) => Promise<void>;

packages/opentelemetry-core/src/internal/http-clients/fetch.ts

@@ -0,0 +1,62 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import {
+  HttpClientError,
+  isRetriableStatusCode,
+  parseRetryAfterToMills,
+  RequestFunction,
+  RetriableError,
+} from '../http-client';
+
+export const isFetchRequestAvailable = () => {
+  return typeof fetch === 'function';
+};
+export const fetchRequest: RequestFunction = (url, payload, requestInit) => {
+  const abortController = new AbortController();
+  let timeout: ReturnType<typeof setTimeout> | undefined;
+  if (requestInit?.timeoutMs) {
+    timeout = setTimeout(() => {
+      abortController.abort();
+    }, requestInit?.timeoutMs);
+  }
+
+  return fetch(url, {
+    body: payload,
+    method: requestInit?.method,
+    headers: requestInit?.headers,
+    signal: abortController.signal,
+  }).then(
+    response => {
+      clearTimeout(timeout);
+      if (response.status >= 200 && response.status <= 299) {
+        return;
+      }
+      const error = new HttpClientError(response.statusText, response.status);
+      if (isRetriableStatusCode(response.status)) {
+        throw new RetriableError(
+          parseRetryAfterToMills(response.headers.get('Retry-After')),
+          error
+        );
+      }
+      throw error;
+    },
+    error => {
+      clearTimeout(timeout);
+      throw error;
+    }
+  );
+};

packages/opentelemetry-core/src/internal/http-export.ts

@@ -0,0 +1,142 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { diag } from '@opentelemetry/api';
+import { ExportResult, ExportResultCode } from '../ExportResult';
+import {
+  BufferLike,
+  HttpClient,
+  isRetriableError,
+  RequestFunction,
+  RequestInit,
+} from './http-client';
+import { fetchRequest, isFetchRequestAvailable } from './http-clients/fetch';
+import { internal } from '../platform';
+
+export interface ExportOptions extends RequestInit {
+  /**
+   * Defaults to 0.
+   */
+  maxAttempts?: number;
+  initialBackoff?: number;
+  maxBackoff?: number;
+  backoffMultiplier?: number;
+}
+
+const DEFAULT_EXPORT_MAX_ATTEMPTS = 5;
+const DEFAULT_EXPORT_INITIAL_BACKOFF = 1000;
+const DEFAULT_EXPORT_MAX_BACKOFF = 5000;
+const DEFAULT_EXPORT_BACKOFF_MULTIPLIER = 1.5;
+
+const clients = {
+  fetch: [isFetchRequestAvailable, fetchRequest],
+  'node:http': [internal.isHttpRequestAvailable, internal.httpRequest],
+  XMLHttpReuqest: [internal.isXhrRequestAvailable, internal.xhrRequest],
+  sendBeacon: [
+    internal.isSendBeaconRequestAvailable,
+    internal.sendBeaconRequest,
+  ],
+} as const;
+export function determineClient(
+  preferredClients: HttpClient[]
+): RequestFunction {
+  for (let idx = 0; idx < preferredClients.length; idx++) {
+    const name = preferredClients[idx];
+    if (!(name in clients)) {
+      diag.error(`Http client "${name}" is not recognizable.`);
+      continue;
+    }
+    const [test, request] = clients[name];
+    if (!test()) {
+      diag.error(`Http client "${name}" is not available.`);
+      continue;
+    }
+    return request;
+  }
+  throw new Error(`No http client available: ${preferredClients}`);
+}
+
+export type HttpExportClient = (
+  url: string,
+  payload: BufferLike,
+  options?: ExportOptions
+) => Promise<ExportResult>;
+
+/**
+ * Creates a http-client based on the preference of the underlying methods.
+ * The abstract http-client only exposes necessary information to the exporters
+ * in order to broaden the compatibility across platforms.
+ */
+export function createHttpExportClient(
+  preferredClients: HttpClient[]
+): HttpExportClient {
+  const request = determineClient(preferredClients);
+
+  /**
+   * Wraps common retrying process with http clients.
+   */
+  return function httpExport(url, payload, options) {
+    let attemptCount = 0;
+    const maxAttempt = options?.maxAttempts ?? DEFAULT_EXPORT_MAX_ATTEMPTS;
+    const maxBackoff = options?.maxBackoff ?? DEFAULT_EXPORT_MAX_BACKOFF;
+    const initialBackoff =
+      options?.initialBackoff ?? DEFAULT_EXPORT_INITIAL_BACKOFF;
+    const backoffMultiplier =
+      options?.backoffMultiplier ?? DEFAULT_EXPORT_BACKOFF_MULTIPLIER;
+
+    let lastBackoff = initialBackoff;
+
+    const okHandler = (): ExportResult => {
+      return {
+        code: ExportResultCode.SUCCESS,
+      };
+    };
+    const errorHandler = (
+      err: unknown
+    ): Promise<ExportResult> | ExportResult => {
+      if (!isRetriableError(err) || attemptCount >= maxAttempt) {
+        return {
+          code: ExportResultCode.FAILED,
+          error: err as Error,
+        };
+      }
+
+      let delay: number;
+      if (err.retryAfterMillis >= 0) {
+        delay = err.retryAfterMillis;
+      } else {
+        delay =
+          Math.round(Math.random() * (maxBackoff - lastBackoff) + lastBackoff) *
+          backoffMultiplier;
+      }
+
+      lastBackoff = delay;
+      attemptCount++;
+      return setTimeoutPromise(err.retryAfterMillis)
+        .then(() => request(url, payload, options))
+        .then(okHandler, errorHandler);
+    };
+    const p = request(url, payload, options).then(okHandler, errorHandler);
+
+    return p;
+  };
+}
+
+function setTimeoutPromise(timeoutMs: number): Promise<void> {
+  return new Promise(resolve => {
+    setTimeout(resolve, timeoutMs);
+  });
+}

packages/opentelemetry-core/src/internal/index.ts

@@ -0,0 +1,30 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { _export } from './exporter';
+import { HttpClient } from './http-client';
+import {
+  createHttpExportClient,
+  HttpExportClient,
+  ExportOptions,
+} from './http-export';
+export {
+  _export,
+  createHttpExportClient,
+  HttpClient,
+  HttpExportClient,
+  ExportOptions,
+};

packages/opentelemetry-core/src/platform/browser/index.ts

@@ -21,3 +21,6 @@ export * from './RandomIdGenerator';
 export * from './performance';
 export * from './sdk-info';
 export * from './timer-util';
+
+import * as internal from './internal';
+export { internal };

packages/opentelemetry-exporter-zipkin/src/platform/browser/index.ts → packages/opentelemetry-core/src/platform/browser/internal/index.ts

@@ -14,4 +14,6 @@
  * limitations under the License.
  */
 
-export * from './util';
+export { httpRequest, isHttpRequestAvailable } from './node-http';
+export { isSendBeaconRequestAvailable, sendBeaconRequest } from './send-beacon';
+export { isXhrRequestAvailable, xhrRequest } from './xhr';