feat(node): allow keepAlive override (#6161)

We want to reduce the network pressure during profiling and reuse the connection if possible so that we dont block test execution when profiling tests. This change allows us to leverage http connection keepalive by overriding the default SDK value (false). Since the tests that we profile run on node 18, we should not see any memory leaks and it is probably a good practice to allow an override here anyways.

Author: JonasBa

packages/node/src/transports/http.ts

@@ -23,6 +23,8 @@ export interface NodeTransportOptions extends BaseTransportOptions {
   caCerts?: string | Buffer | Array<string | Buffer>;
   /** Custom HTTP module. Defaults to the native 'http' and 'https' modules. */
   httpModule?: HTTPModule;
+  /** Allow overriding connection keepAlive, defaults to false */
+  keepAlive?: boolean;
 }
 
 // Estimated maximum size for reasonable standalone event
@@ -56,12 +58,13 @@ export function makeNodeTransport(options: NodeTransportOptions): Transport {
   );
 
   const nativeHttpModule = isHttps ? https : http;
+  const keepAlive = options.keepAlive === undefined ? false : options.keepAlive;
 
   // TODO(v7): Evaluate if we can set keepAlive to true. This would involve testing for memory leaks in older node
   // versions(>= 8) as they had memory leaks when using it: #2555
   const agent = proxy
     ? (new (require('https-proxy-agent'))(proxy) as http.Agent)
-    : new nativeHttpModule.Agent({ keepAlive: false, maxSockets: 30, timeout: 2000 });
+    : new nativeHttpModule.Agent({ keepAlive, maxSockets: 30, timeout: 2000 });
 
   const requestExecutor = createRequestExecutor(options, options.httpModule ?? nativeHttpModule, agent);
   return createTransport(options, requestExecutor);

packages/node/test/transports/http.test.ts

@@ -108,6 +108,20 @@ describe('makeNewHttpTransport()', () => {
       await transport.send(EVENT_ENVELOPE);
     });
 
+    it('allows overriding keepAlive', async () => {
+      await setupTestServer({ statusCode: SUCCESS }, req => {
+        expect(req.headers).toEqual(
+          expect.objectContaining({
+            // node http module lower-cases incoming headers
+            connection: 'keep-alive',
+          }),
+        );
+      });
+
+      const transport = makeNodeTransport({ keepAlive: true, ...defaultOptions });
+      await transport.send(EVENT_ENVELOPE);
+    });
+
     it('should correctly send user-provided headers to server', async () => {
       await setupTestServer({ statusCode: SUCCESS }, req => {
         expect(req.headers).toEqual(