fix(elbv2): dropInvalidHeaderFields not reflected in CloudFormation when set to false

packages/aws-cdk-lib/aws-elasticloadbalancingv2/lib/alb/application-load-balancer.ts

@@ -228,7 +228,7 @@ export class ApplicationLoadBalancer extends BaseLoadBalancer implements IApplic
 
     if (props.http2Enabled !== undefined) { this.setAttribute('routing.http2.enabled', props.http2Enabled ? 'true' : 'false'); }
     if (props.idleTimeout !== undefined) { this.setAttribute('idle_timeout.timeout_seconds', props.idleTimeout.toSeconds().toString()); }
-    if (props.dropInvalidHeaderFields) { this.setAttribute('routing.http.drop_invalid_header_fields.enabled', 'true'); }
+    if (props.dropInvalidHeaderFields !== undefined) { this.setAttribute('routing.http.drop_invalid_header_fields.enabled', props.dropInvalidHeaderFields ? 'true' : 'false'); }
     if (props.desyncMitigationMode !== undefined) { this.setAttribute('routing.http.desync_mitigation_mode', props.desyncMitigationMode); }
     if (props.preserveHostHeader) { this.setAttribute('routing.http.preserve_host_header.enabled', 'true'); }
     if (props.xAmznTlsVersionAndCipherSuiteHeaders) { this.setAttribute('routing.http.x_amzn_tls_version_and_cipher_suite.enabled', 'true'); }

packages/aws-cdk-lib/aws-elasticloadbalancingv2/test/alb/load-balancer.test.ts

@@ -173,6 +173,28 @@ describe('tests', () => {
     });
   });
 
+  test('setting dropInvalidHeaderFields to false includes attribute in template', () => {
+    // GIVEN
+    const stack = new cdk.Stack();
+    const vpc = new ec2.Vpc(stack, 'Stack');
+
+    // WHEN
+    new elbv2.ApplicationLoadBalancer(stack, 'LB', {
+      vpc,
+      dropInvalidHeaderFields: false,
+    });
+
+    // THEN
+    Template.fromStack(stack).hasResourceProperties('AWS::ElasticLoadBalancingV2::LoadBalancer', {
+      LoadBalancerAttributes: Match.arrayWith([
+        {
+          Key: 'routing.http.drop_invalid_header_fields.enabled',
+          Value: 'false',
+        },
+      ]),
+    });
+  });
+
   test.each([59, 604801])('throw error for invalid clientKeepAlive in seconds', (duration) => {
     // GIVEN
     const stack = new cdk.Stack();