feat(otlp-exporter-base): internally accept a http header provider function only

experimental/CHANGELOG.md

@@ -7,6 +7,21 @@ All notable changes to experimental packages in this project will be documented
 
 ### :boom: Breaking Change
 
+* feat(otlp-exporter-base)!: collapse base classes into one [#5031](https://github.com/open-telemetry/opentelemetry-js/pull/5031) @pichlermarc
+  * `OTLPExporterNodeBase` has been removed in favor of a platform-agnostic implementation (`OTLPExporterBase`)
+  * `OTLPExporterBrowserBase` has been removed in favor of a platform-agnostic implementation (`OTLPExporterBase`)
+  * `ExportServiceError` was intended for internal use and has been dropped from exports
+  * `validateAndNormalizeHeaders` was intended for internal use and has been dropped from exports
+  * `OTLPExporterBase` all properties are now private, the constructor now takes an `IOTLPExportDelegate`, the type parameter for config type has been dropped.
+    * This type is scheduled for removal in a future version of this package, please treat all exporters as `SpanExporter`, `PushMetricExporter` or `LogRecordExporter`, based on their respective type.
+* feat(otlp-grpc-exporter-base)!: collapse base classes into one [#5031](https://github.com/open-telemetry/opentelemetry-js/pull/5031) @pichlermarc
+  * `OTLPGRPCExporterNodeBase` has been removed in favor of a platform-agnostic implementation (`OTLPExporterBase` from `@opentelemetry/otlp-exporter-base`)
+* feat(otlp-exporter-base): internally accept a http header provider function only [#5179](https://github.com/open-telemetry/opentelemetry-js/pull/5179) @pichlermarc
+* feat(otlp-transformer)!: accept `ResourceMetrics` in serializers instead of `ResourceMetrics[]`
+  * (user-facing): `ProtobufMetricsSerializer` now only accepts `ResourceMetrics` instead of `ResourceMetrics[]` to align with `PushMetricExporter` requirements
+  * (user-facing): `JsonMetricsSerializer` now only accepts `ResourceMetrics` instead of `ResourceMetrics[]` to align with `PushMetricExporter` requirements
+
+
 ### :rocket: (Enhancement)
 
 ### :bug: (Bug Fix)
@@ -53,18 +68,6 @@ All notable changes to experimental packages in this project will be documented
     * GetFunction
     * Func
     * Err
-* feat(otlp-exporter-base)!: collapse base classes into one [#5031](https://github.com/open-telemetry/opentelemetry-js/pull/5031)
-  * `OTLPExporterNodeBase` has been removed in favor of a platform-agnostic implementation (`OTLPExporterBase`)
-  * `OTLPExporterBrowserBase` has been removed in favor of a platform-agnostic implementation (`OTLPExporterBase`)
-  * `ExportServiceError` was intended for internal use and has been dropped from exports
-  * `validateAndNormalizeHeaders` was intended for internal use and has been dropped from exports
-  * `OTLPExporterBase` all properties are now private, the constructor now takes an `IOTLPExportDelegate`, the type parameter for config type has been dropped.
-    * This type is scheduled for removal in a future version of this package, please treat all exporters as `SpanExporter`, `PushMetricExporter` or `LogRecordExporter`, based on their respective type.
-* feat(otlp-grpc-exporter-base)!: collapse base classes into one [#5031](https://github.com/open-telemetry/opentelemetry-js/pull/5031)
-  * `OTLPGRPCExporterNodeBase` has been removed in favor of a platform-agnostic implementation (`OTLPExporterBase` from `@opentelemetry/otlp-exporter-base`)
-* feat(otlp-transformer)!: accept `ResourceMetrics` in serializers instead of `ResourceMetrics[]`
-  * (user-facing): `ProtobufMetricsSerializer` now only accepts `ResourceMetrics` instead of `ResourceMetrics[]` to align with `PushMetricExporter` requirements
-  * (user-facing): `JsonMetricsSerializer` now only accepts `ResourceMetrics` instead of `ResourceMetrics[]` to align with `PushMetricExporter` requirements
 
 ### :rocket: (Enhancement)
 

experimental/packages/otlp-exporter-base/src/configuration/convert-legacy-browser-http-options.ts

@@ -19,6 +19,7 @@ import {
   OtlpHttpConfiguration,
 } from './otlp-http-configuration';
 import { OTLPExporterNodeConfigBase } from './legacy-node-configuration';
+import { wrapStaticHeadersInFunction } from './shared-configuration';
 
 /**
  * @deprecated this will be removed in 2.0
@@ -36,7 +37,7 @@ export function convertLegacyBrowserHttpOptions(
     {
       url: config.url,
       timeoutMillis: config.timeoutMillis,
-      headers: config.headers,
+      headers: wrapStaticHeadersInFunction(config.headers),
       concurrencyLimit: config.concurrencyLimit,
     },
     {}, // no fallback for browser case

experimental/packages/otlp-exporter-base/src/configuration/convert-legacy-node-http-options.ts

@@ -23,6 +23,7 @@ import { getHttpConfigurationFromEnvironment } from './otlp-http-env-configurati
 import type * as http from 'http';
 import type * as https from 'https';
 import { diag } from '@opentelemetry/api';
+import { wrapStaticHeadersInFunction } from './shared-configuration';
 
 function convertLegacyAgentOptions(
   config: OTLPExporterNodeConfigBase
@@ -67,7 +68,7 @@ export function convertLegacyHttpOptions(
   return mergeOtlpHttpConfigurationWithDefaults(
     {
       url: config.url,
-      headers: config.headers,
+      headers: wrapStaticHeadersInFunction(config.headers),
       concurrencyLimit: config.concurrencyLimit,
       timeoutMillis: config.timeoutMillis,
       compression: config.compression,

experimental/packages/otlp-exporter-base/src/configuration/otlp-http-configuration.ts

@@ -27,32 +27,34 @@ import type * as https from 'https';
 
 export interface OtlpHttpConfiguration extends OtlpSharedConfiguration {
   url: string;
-  headers: Record<string, string>;
+  headers: () => Record<string, string>;
   agentOptions: http.AgentOptions | https.AgentOptions;
 }
 
 function mergeHeaders(
-  userProvidedHeaders: Record<string, string> | undefined | null,
-  fallbackHeaders: Record<string, string> | undefined | null,
-  defaultHeaders: Record<string, string>
-): Record<string, string> {
+  userProvidedHeaders: (() => Record<string, string>) | undefined | null,
+  fallbackHeaders: (() => Record<string, string>) | undefined | null,
+  defaultHeaders: () => Record<string, string>
+): () => Record<string, string> {
   const requiredHeaders = {
-    ...defaultHeaders,
+    ...defaultHeaders(),
   };
   const headers = {};
 
-  // add fallback ones first
-  if (fallbackHeaders != null) {
-    Object.assign(headers, fallbackHeaders);
-  }
+  return () => {
+    // add fallback ones first
+    if (fallbackHeaders != null) {
+      Object.assign(headers, fallbackHeaders());
+    }
 
-  // override with user-provided ones
-  if (userProvidedHeaders != null) {
-    Object.assign(headers, userProvidedHeaders);
-  }
+    // override with user-provided ones
+    if (userProvidedHeaders != null) {
+      Object.assign(headers, userProvidedHeaders());
+    }
 
-  // override required ones.
-  return Object.assign(headers, requiredHeaders);
+    // override required ones.
+    return Object.assign(headers, requiredHeaders);
+  };
 }
 
 function validateUserProvidedUrl(url: string | undefined): string | undefined {
@@ -107,7 +109,7 @@ export function getHttpConfigurationDefaults(
 ): OtlpHttpConfiguration {
   return {
     ...getSharedConfigurationDefaults(),
-    headers: requiredHeaders,
+    headers: () => requiredHeaders,
     url: 'http://localhost:4318/' + signalResourcePath,
     agentOptions: { keepAlive: true },
   };

experimental/packages/otlp-exporter-base/src/configuration/otlp-http-env-configuration.ts

@@ -17,8 +17,11 @@ import { baggageUtils } from '@opentelemetry/core';
 import { diag } from '@opentelemetry/api';
 import { getSharedConfigurationFromEnvironment } from './shared-env-configuration';
 import { OtlpHttpConfiguration } from './otlp-http-configuration';
+import { wrapStaticHeadersInFunction } from './shared-configuration';
 
-function getHeadersFromEnv(signalIdentifier: string) {
+function getStaticHeadersFromEnv(
+  signalIdentifier: string
+): Record<string, string> | undefined {
   const signalSpecificRawHeaders =
     process.env[`OTEL_EXPORTER_OTLP_${signalIdentifier}_HEADERS`]?.trim();
   const nonSignalSpecificRawHeaders =
@@ -126,6 +129,8 @@ export function getHttpConfigurationFromEnvironment(
     url:
       getSpecificUrlFromEnv(signalIdentifier) ??
       getNonSpecificUrlFromEnv(signalResourcePath),
-    headers: getHeadersFromEnv(signalIdentifier),
+    headers: wrapStaticHeadersInFunction(
+      getStaticHeadersFromEnv(signalIdentifier)
+    ),
   };
 }

experimental/packages/otlp-exporter-base/src/configuration/shared-configuration.ts

@@ -41,6 +41,16 @@ export function validateTimeoutMillis(timeoutMillis: number) {
   );
 }
 
+export function wrapStaticHeadersInFunction(
+  headers: Record<string, string> | undefined
+): (() => Record<string, string>) | undefined {
+  if (headers == null) {
+    return undefined;
+  }
+
+  return () => headers;
+}
+
 /**
  * @param userProvidedConfiguration  Configuration options provided by the user in code.
  * @param fallbackConfiguration Fallback to use when the {@link userProvidedConfiguration} does not specify an option.

experimental/packages/otlp-exporter-base/src/otlp-browser-http-export-delegate.ts

@@ -44,7 +44,7 @@ export function createOtlpSendBeaconExportDelegate<Internal, Response>(
     createRetryingTransport({
       transport: createSendBeaconTransport({
         url: options.url,
-        blobType: options.headers['Content-Type'],
+        blobType: options.headers()['Content-Type'],
       }),
     })
   );

experimental/packages/otlp-exporter-base/src/transport/http-transport-types.ts

@@ -28,7 +28,7 @@ export type sendWithHttp = (
 
 export interface HttpRequestParameters {
   url: string;
-  headers: Record<string, string>;
+  headers: () => Record<string, string>;
   compression: 'gzip' | 'none';
   agentOptions: http.AgentOptions | https.AgentOptions;
 }

experimental/packages/otlp-exporter-base/src/transport/http-transport-utils.ts

@@ -49,7 +49,7 @@ export function sendWithHttp(
     path: parsedUrl.pathname,
     method: 'POST',
     headers: {
-      ...params.headers,
+      ...params.headers(),
     },
     agent: agent,
   };

experimental/packages/otlp-exporter-base/src/transport/xhr-transport.ts

@@ -24,7 +24,7 @@ import {
 
 export interface XhrRequestParameters {
   url: string;
-  headers: Record<string, string>;
+  headers: () => Record<string, string>;
 }
 
 class XhrTransport implements IExporterTransport {
@@ -35,7 +35,8 @@ class XhrTransport implements IExporterTransport {
       const xhr = new XMLHttpRequest();
       xhr.timeout = timeoutMillis;
       xhr.open('POST', this._parameters.url);
-      Object.entries(this._parameters.headers).forEach(([k, v]) => {
+      const headers = this._parameters.headers();
+      Object.entries(headers).forEach(([k, v]) => {
         xhr.setRequestHeader(k, v);
       });
 
@@ -80,9 +81,7 @@ class XhrTransport implements IExporterTransport {
         });
       };
 
-      xhr.send(
-        new Blob([data], { type: this._parameters.headers['Content-Type'] })
-      );
+      xhr.send(new Blob([data], { type: headers['Content-Type'] }));
     });
   }
 

experimental/packages/otlp-exporter-base/src/util.ts

@@ -21,17 +21,19 @@ import { diag } from '@opentelemetry/api';
  * @param partialHeaders
  */
 export function validateAndNormalizeHeaders(
-  partialHeaders: Partial<Record<string, unknown>> = {}
-): Record<string, string> {
-  const headers: Record<string, string> = {};
-  Object.entries(partialHeaders).forEach(([key, value]) => {
-    if (typeof value !== 'undefined') {
-      headers[key] = String(value);
-    } else {
-      diag.warn(
-        `Header "${key}" has invalid value (${value}) and will be ignored`
-      );
-    }
-  });
-  return headers;
+  partialHeaders: (() => Record<string, string>) | undefined
+): () => Record<string, string> {
+  return () => {
+    const headers: Record<string, string> = {};
+    Object.entries(partialHeaders?.() ?? {}).forEach(([key, value]) => {
+      if (typeof value !== 'undefined') {
+        headers[key] = String(value);
+      } else {
+        diag.warn(
+          `Header "${key}" has invalid value (${value}) and will be ignored`
+        );
+      }
+    });
+    return headers;
+  };
 }

experimental/packages/otlp-exporter-base/test/browser/xhr-transport.test.ts

@@ -26,11 +26,11 @@ import { ensureHeadersContain } from '../testHelper';
 
 const testTransportParameters = {
   url: 'http://example.test',
-  headers: {
+  headers: () => ({
     foo: 'foo-value',
     bar: 'bar-value',
     'Content-Type': 'application/json',
-  },
+  }),
 };
 
 const requestTimeout = 1000;

experimental/packages/otlp-exporter-base/test/common/configuration/otlp-http-configuration.test.ts

@@ -27,22 +27,22 @@ describe('mergeOtlpHttpConfigurationWithDefaults', function () {
     timeoutMillis: 1,
     compression: 'none',
     concurrencyLimit: 2,
-    headers: { 'User-Agent': 'default-user-agent' },
+    headers: () => ({ 'User-Agent': 'default-user-agent' }),
     agentOptions: { keepAlive: true },
   };
 
   describe('headers', function () {
     it('merges headers instead of overriding', function () {
       const config = mergeOtlpHttpConfigurationWithDefaults(
         {
-          headers: { foo: 'user' },
+          headers: () => ({ foo: 'user' }),
         },
         {
-          headers: { foo: 'fallback', bar: 'fallback' },
+          headers: () => ({ foo: 'fallback', bar: 'fallback' }),
         },
         testDefaults
       );
-      assert.deepStrictEqual(config.headers, {
+      assert.deepStrictEqual(config.headers(), {
         'User-Agent': 'default-user-agent',
         foo: 'user',
         bar: 'fallback',
@@ -52,14 +52,14 @@ describe('mergeOtlpHttpConfigurationWithDefaults', function () {
     it('does not override default (required) header', function () {
       const config = mergeOtlpHttpConfigurationWithDefaults(
         {
-          headers: { 'User-Agent': 'custom' },
+          headers: () => ({ 'User-Agent': 'custom' }),
         },
         {
-          headers: { 'User-Agent': 'custom-fallback' },
+          headers: () => ({ 'User-Agent': 'custom-fallback' }),
         },
         testDefaults
       );
-      assert.deepStrictEqual(config.headers, {
+      assert.deepStrictEqual(config.headers(), {
         'User-Agent': 'default-user-agent',
       });
     });
@@ -69,12 +69,16 @@ describe('mergeOtlpHttpConfigurationWithDefaults', function () {
         {
           // eslint-disable-next-line @typescript-eslint/ban-ts-comment
           // @ts-ignore simulating plain JavaScript usage, ignoring types
-          headers: { foo: 'foo-user-provided', bar: undefined, baz: null },
+          headers: () => ({
+            foo: 'foo-user-provided',
+            bar: undefined,
+            baz: null,
+          }),
         },
         {},
         testDefaults
       );
-      assert.deepStrictEqual(config.headers, {
+      assert.deepStrictEqual(config.headers(), {
         foo: 'foo-user-provided',
         baz: 'null',
         'User-Agent': 'default-user-agent',

experimental/packages/otlp-exporter-base/test/common/util.test.ts

@@ -31,7 +31,9 @@ describe('parseHeaders', function () {
       foo2: 'bar',
       foo3: 1,
     };
-    const result = validateAndNormalizeHeaders(headers);
+    // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+    // @ts-ignore simulating plain JS usage
+    const result = validateAndNormalizeHeaders(() => headers)();
     assert.deepStrictEqual(result, {
       foo2: 'bar',
       foo3: '1',
@@ -44,7 +46,7 @@ describe('parseHeaders', function () {
   });
 
   it('should parse undefined', function () {
-    const result = validateAndNormalizeHeaders(undefined);
+    const result = validateAndNormalizeHeaders(undefined)();
     assert.deepStrictEqual(result, {});
   });
 });

experimental/packages/otlp-exporter-base/test/node/configuration/otlp-http-env-configuration.test.ts

@@ -49,7 +49,7 @@ describe('getHttpConfigurationFromEnvironment', function () {
         'METRICS',
         'v1/metrics'
       );
-      assert.deepEqual(config.headers, {
+      assert.deepEqual(config.headers?.(), {
         key1: 'metrics',
         key2: 'value2',
       });
@@ -62,7 +62,7 @@ describe('getHttpConfigurationFromEnvironment', function () {
         'METRICS',
         'v1/metrics'
       );
-      assert.deepEqual(config.headers, {
+      assert.deepEqual(config.headers?.(), {
         key1: 'value1',
         key2: 'value2',
       });
@@ -76,7 +76,7 @@ describe('getHttpConfigurationFromEnvironment', function () {
         'METRICS',
         'v1/metrics'
       );
-      assert.deepEqual(config.headers, {
+      assert.deepEqual(config.headers?.(), {
         key1: 'value1',
         key2: 'value2',
       });