CDK creating additional stack for ELB resources

Question

I'm using CDK to create a stack with some ELB resources. Everything seems to be working correctly, but I end up with two CloudFormation stacks. One named demo and another that has a randomly generated name like awseb-e-jkmuguqm3e-stack.

The demo stack has the ElasticBeanstalk Application and Environment, but the other stack has a bunch of load balancer resources, including an AutoScalingGroup, LaunchConfiguration, ScalingPolicy, etc, that I assume are created as part of the ELB stuff, but I would think they'd end up in the same stack?

disclaimer: this might be entirely expected behavior, as everything works, but being new to CDK I figured someone might know why i get an extra stack here, and maybe there is something I can do to prevent it

I've defined an AppStack (cdk-app/index.ts):

export class AppStack extends cdk.Stack {
  constructor(scope: cdk.App, id: string, props?: cdk.StackProps) {
    super(scope, id, props);


    const stackName = _.get(props, ['stackName'], '');

    const app = new elasticBeanstalk.CfnApplication(this, `${stackName}EbsApplication`, {
      applicationName: `${_.toLower(stackName)}-ebs-app`
    });

    const ebsInstanceRole = new iam.Role(
      this,
      `${stackName}EBSInstanceRole`,
      {
        roleName: `${_.toLower(stackName)}-ebs-role`,
        assumedBy: new iam.ServicePrincipal('ec2.amazonaws.com'),
      }
    );

    // create an instance profile the that instances in our EBS environment will use
    const ebsInstanceProfile = new iam.CfnInstanceProfile(
      this,
      `${stackName}InstanceProfile`,
      {
        instanceProfileName: `${_.toLower(stackName)}-ebs-instance-profile`,
        roles: [
          ebsInstanceRole.roleName,
        ],
      }
    );

    const env = new elasticBeanstalk.CfnEnvironment(this, 'Environment', {
      environmentName: `${_.toLower(stackName)}-ebs-env`,
      applicationName: `${_.toLower(stackName)}-ebs-app`,
      solutionStackName: '64bit Amazon Linux 2 v5.0.2 running Node.js 12',
      optionSettings: [
        {
          namespace: 'aws:autoscaling:launchconfiguration',
          optionName: 'IamInstanceProfile',
          value: ebsInstanceProfile.instanceProfileName,

        }
      ]
    });
  }
}

export default AppStack;

I use the stack (index.ts):

import AppStack from "./cdk-app";

const app = new cdk.App();

const appStack = new AppStack(app, 'demoAppStack', { stackName: 'demo' });

app.synth();

cant see where you create a stack. the code just creates resources with a prefix from a variable called stackName — Logemann
@Marc sorry, this code all lives within the constructor for a stack, I'll update the example — Donald P
Without knowing much about the stack code itself I want to bring up two things to clarify here. 1. You have exported the stack twice export class AppStack extends cdk.Stack and export default AppStack; 2. How are you importing the stack when you are using it just before app.synth();? — dmahapatro
@dmahapatro im importing it using the default export, ie import App stack from '../AppStack', I'll update example code. It is exporting twice but I don't think that should matter (the named export doesn't get used). Thank you for looking it over. — Donald P

Michael Snook Michael Snook · Accepted Answer · 2021-03-11T21:04:21

I believe this is just how Elastic Beanstalk works. It creates a nested stack for you (i.e., awseb-e-jkmuguqm3e-stack in your case). If you want to avoid it, I think you'd need to stop using Elastic Beanstalk.

Also worth noting what you are seeing is not CDK-specific. You'll also see the additional 'random' stack created when defining an EB stack using Cloudformation and when creating an EB environment via the AWS console.

CDK creating additional stack for ELB resources

1 Answers