AutoScaling LaunchConfiguration Assigns Public IP

What this rule checks

Detects AWS::AutoScaling::LaunchConfiguration with AssociatePublicIpAddress=true. Instances launched from this configuration get a public IP and are internet-reachable directly.

How to fix it

1. 1Set AssociatePublicIpAddress to false on the LaunchConfiguration
2. 2Place instances in private subnets behind an ALB / NLB
3. 3Use a NAT Gateway / VPC endpoints for outbound traffic
4. 4Migrate to AWS::EC2::LaunchTemplate (LaunchConfiguration is deprecated)

import { aws_ec2 as ec2, aws_autoscaling as autoscaling } from 'aws-cdk-lib';

const vpc = new ec2.Vpc(this, 'Vpc');

const lc = new autoscaling.CfnLaunchConfiguration(this, 'Lc', {
  imageId: 'ami-0abcdef1234567890',
  instanceType: 't3.micro',
  associatePublicIpAddress: true,
});

import { aws_ec2 as ec2, aws_autoscaling as autoscaling } from 'aws-cdk-lib';

const vpc = new ec2.Vpc(this, 'Vpc');

const asg = new autoscaling.AutoScalingGroup(this, 'Asg', {
  vpc,
  vpcSubnets: { subnetType: ec2.SubnetType.PRIVATE_WITH_EGRESS },
  instanceType: ec2.InstanceType.of(ec2.InstanceClass.T3, ec2.InstanceSize.MICRO),
  machineImage: ec2.MachineImage.latestAmazonLinux2023(),
  associatePublicIpAddress: false,
});

CDK Insights pinpoints the exact file and line in your CDK source for every finding, so you can jump straight to the fix.

Affected resource types

Intentional? Suppress this finding

Sometimes a flag is deliberate — a genuinely public endpoint, say. You can dismiss autoscaling-launch-config-public-ip and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "autoscaling-launch-config-public-ip", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::autoscaling-launch-config-public-ip',
  reason: 'Why this is intentional',
});

Use the rule ID autoscaling-launch-config-public-ip shown above — not the CDK-* ID from SARIF / GitHub code scanning. To dismiss every finding on one construct instead, use ignorePaths. Suppression docs →

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