Use the Headers object for better typing

Author: mghaznav

packages/telemetry/src/logging/appcheck-provider.ts

@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-import { DynamicHeaderProvider } from '../types';
+import { DynamicHeaderProvider, HttpHeader } from '../types';
 import { Provider } from '@firebase/component';
 import {
   FirebaseAppCheckInternal,
@@ -40,7 +40,7 @@ export class AppCheckProvider implements DynamicHeaderProvider {
     }
   }
 
-  async getHeader(): Promise<Record<string, string> | null> {
+  async getHeader(): Promise<HttpHeader | null> {
     if (!this.appCheck) {
       return null;
     }
@@ -52,6 +52,6 @@ export class AppCheckProvider implements DynamicHeaderProvider {
       return null;
     }
 
-    return { 'X-Firebase-AppCheck': appCheckToken.token };
+    return ['X-Firebase-AppCheck', appCheckToken.token];
   }
 }

packages/telemetry/src/logging/fetch-transport.test.ts

@@ -30,7 +30,7 @@ import {
 
 const testTransportParameters = {
   url: 'http://example.test',
-  headers: () => ({
+  headers: new Headers({
     foo: 'foo-value',
     bar: 'bar-value',
     'Content-Type': 'application/json'
@@ -68,11 +68,11 @@ describe('FetchTransport', () => {
             testTransportParameters.url,
             {
               method: 'POST',
-              headers: {
+              headers: new Headers({
                 foo: 'foo-value',
                 bar: 'bar-value',
                 'Content-Type': 'application/json'
-              },
+              }),
               body: testPayload
             }
           );
@@ -182,7 +182,7 @@ describe('FetchTransport', () => {
         .resolves(new Response('test response', { status: 200 }));
 
       const dynamicProvider: DynamicHeaderProvider = {
-        getHeader: sinon.stub().resolves({ 'dynamic-header': 'dynamic-value' })
+        getHeader: sinon.stub().resolves(['dynamic-header', 'dynamic-value'])
       };
 
       const transport = new FetchTransport({
@@ -200,12 +200,12 @@ describe('FetchTransport', () => {
             testTransportParameters.url,
             {
               method: 'POST',
-              headers: {
+              headers: new Headers({
                 foo: 'foo-value',
                 bar: 'bar-value',
                 'Content-Type': 'application/json',
                 'dynamic-header': 'dynamic-value'
-              },
+              }),
               body: testPayload
             }
           );
@@ -241,7 +241,7 @@ describe('FetchTransport', () => {
             testTransportParameters.url,
             {
               method: 'POST',
-              headers: testTransportParameters.headers(),
+              headers: testTransportParameters.headers,
               body: testPayload
             }
           );

packages/telemetry/src/logging/fetch-transport.ts

@@ -53,7 +53,7 @@ function parseRetryAfterToMills(
 /** @internal */
 export interface FetchTransportParameters {
   url: string;
-  headers: () => Record<string, string>;
+  headers: Headers;
   dynamicHeaders?: DynamicHeaderProvider[];
 }
 
@@ -70,7 +70,7 @@ export class FetchTransport implements IExporterTransport {
     const timeout = setTimeout(() => abortController.abort(), timeoutMillis);
     try {
       const url = new URL(this.parameters.url);
-      const headers = this.parameters.headers();
+      const headers = this.parameters.headers;
 
       if (
         this.parameters.dynamicHeaders &&
@@ -83,7 +83,7 @@ export class FetchTransport implements IExporterTransport {
 
         for (const header of resolvedHeaders) {
           if (header) {
-            Object.assign(headers, header);
+            headers.append(...header);
           }
         }
       }

packages/telemetry/src/logging/logger-provider.ts

@@ -79,7 +79,7 @@ class OTLPLogExporter
         JsonLogsSerializer,
         new FetchTransport({
           url: config.url!,
-          headers: () => ({
+          headers: new Headers({
             'Content-Type': 'application/json'
           }),
           dynamicHeaders

packages/telemetry/src/types.ts

@@ -15,6 +15,13 @@
  * limitations under the License.
  */
 
+/**
+ * A type for HTTP Headers
+ *
+ * @internal
+ */
+export type HttpHeader = [key: string, value: string];
+
 /**
  * An interface for classes that provide dynamic headers.
  *
@@ -29,5 +36,5 @@ export interface DynamicHeaderProvider {
    * @returns A {@link Promise} that resolves to a {@link Record<string, string>} of header
    * key-value pairs, or null if no headers are to be added.
    */
-  getHeader(): Promise<Record<string, string> | null>;
+  getHeader(): Promise<HttpHeader | null>;
 }