const lb = new elbv2.ApplicationLoadBalancer(this, 'LB', {
      vpc,
      internetFacing: false
    });

    const listener = lb.addListener('Listener', {
      port: 80,
    });

    const fn = lambda.Function.fromFunctionArn(this, 'myFunction', functionARN)

    listener.addTargets('Target', {
      port: 80,
      targets: [new targets.LambdaTarget(fn)]
    });
    
    // @aws-cdk/aws-elasticloadbalancingv2-targets.LambdaTarget
    const lambdaTarget = new targets.LambdaTarget(fn);
    
    new lambda.CfnPermission(this, 'MyRule_MyLambda_InvokePermission', {
          action: 'lambda:InvokeFunction',
          functionName: fn.functionArn,
          principal: 'elasticloadbalancing.amazonaws.com',
          sourceArn: listener.listenerArn
      })
    
    listener.addTargets('Target', {
      port: 80,
      targets: [lambdaTarget]
    })

    listener.connections.allowDefaultPortFromAnyIpv4('test');

No child with id: 'InvokeServicePrincipal(elasticloadbalancing.amazonaws.com)'

/home/ec2-user/environment/monolithic-modernization-lab/root-endpoint/node_modules/@aws-cdk/core/lib/private/synthesis.ts:151
    throw new Error(`Validation failed with the following errors:\n  ${errorList}`);
          ^
Error: Validation failed with the following errors:
  [RootEndpointStack/LB/Listener] Listener needs at least one default action or target group (call addTargetGroups or addAction)
    at validateTree (/home/ec2-user/environment/monolithic-modernization-lab/root-endpoint/node_modules/@aws-cdk/core/lib/private/synthesis.ts:151:11)
    at Object.synthesize (/home/ec2-user/environment/monolithic-modernization-lab/root-endpoint/node_modules/@aws-cdk/core/lib/private/synthesis.ts:25:5)
    at App.synth (/home/ec2-user/environment/monolithic-modernization-lab/root-endpoint/node_modules/@aws-cdk/core/lib/stage.ts:175:23)
    at process.App.process.once (/home/ec2-user/environment/monolithic-modernization-lab/root-endpoint/node_modules/@aws-cdk/core/lib/app.ts:112:45)
    at Object.onceWrapper (events.js:286:20)
    at process.emit (events.js:198:13)
    at process.EventEmitter.emit (domain.js:448:20)
    at process.emit (/home/ec2-user/environment/monolithic-modernization-lab/root-endpoint/node_modules/source-map-support/source-map-support.js:495:21)
    at process.topLevelDomainCallback (domain.js:126:23)