feat(otlp-exporter-base): add http response body to exporter error (#5204)

Author: pichlermarc

experimental/CHANGELOG.md

@@ -25,6 +25,7 @@ All notable changes to experimental packages in this project will be documented
 * feat(otlp-exporter-base): internally accept a http header provider function only [#5179](https://github.com/open-telemetry/opentelemetry-js/pull/5179) @pichlermarc
 * refactor(otlp-exporter-base): don't create blob before sending xhr [#5193](https://github.com/open-telemetry/opentelemetry-js/pull/5193) @pichlermarc
   * improves compatibility with some unsupported runtimes
+* feat(otlp-exporter-base): add http response body to exporter error [#5204](https://github.com/open-telemetry/opentelemetry-js/pull/5204) @pichlermarc
 
 ### :bug: (Bug Fix)
 

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

@@ -72,7 +72,11 @@ export function sendWithHttp(
           retryInMillis: parseRetryAfterToMills(res.headers['retry-after']),
         });
       } else {
-        const error = new OTLPExporterError(res.statusMessage, res.statusCode);
+        const error = new OTLPExporterError(
+          res.statusMessage,
+          res.statusCode,
+          Buffer.concat(responseData).toString()
+        );
         onDone({
           status: 'failure',
           error,

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

@@ -22,6 +22,7 @@ import {
   ExportResponseRetryable,
   ExportResponseFailure,
   ExportResponseSuccess,
+  OTLPExporterError,
 } from '../../src';
 import * as zlib from 'zlib';
 
@@ -123,7 +124,7 @@ describe('HttpExporterTransport', function () {
       // arrange
       server = http.createServer((_, res) => {
         res.statusCode = 404;
-        res.end();
+        res.end('response-body');
       });
       server.listen(8080);
 
@@ -143,6 +144,14 @@ describe('HttpExporterTransport', function () {
         (result as ExportResponseFailure).error.message,
         'Not Found'
       );
+      assert.strictEqual(
+        ((result as ExportResponseFailure).error as OTLPExporterError).data,
+        'response-body'
+      );
+      assert.strictEqual(
+        ((result as ExportResponseFailure).error as OTLPExporterError).code,
+        404
+      );
     });
 
     it('returns failure when request times out', function (done) {