AutoScaling Group Not Using ELB Health Checks

What this rule checks

Detects AWS::AutoScaling::AutoScalingGroup resources attached to a load balancer (LoadBalancerNames or TargetGroupARNs) but using EC2 health checks. EC2 health checks miss app-level outages the load balancer would otherwise detect.

How to fix it

1. 1Set HealthCheckType to ELB on the AutoScalingGroup
2. 2Set HealthCheckGracePeriod to give instances time to bootstrap before the LB starts probing
3. 3Verify the ALB / NLB target group has appropriate health-check thresholds

import { App, Stack } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as asg from 'aws-cdk-lib/aws-autoscaling';

// FLAGGED: ASG behind a target group but using EC2 health checks.
new asg.CfnAutoScalingGroup(this, 'Asg', {
  minSize: '1',
  maxSize: '3',
  availabilityZones: ['us-east-1a'],
  targetGroupArns: ['arn:aws:elasticloadbalancing:us-east-1:123456789012:targetgroup/app/abc'],
  launchConfigurationName: 'app-launch-config',
});

import { App, Stack } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as asg from 'aws-cdk-lib/aws-autoscaling';

// FIXED: ASG uses ELB health checks with a grace period.
new asg.CfnAutoScalingGroup(this, 'Asg', {
  minSize: '1',
  maxSize: '3',
  availabilityZones: ['us-east-1a'],
  targetGroupArns: ['arn:aws:elasticloadbalancing:us-east-1:123456789012:targetgroup/app/abc'],
  launchConfigurationName: 'app-launch-config',
  healthCheckType: 'ELB',
  healthCheckGracePeriod: 120,
});

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-group-no-elb-healthcheck and the reason is kept in the report, not silently hidden.

In .cdk-insights.json:

{
  "ignoreRules": [
    { "id": "autoscaling-group-no-elb-healthcheck", "reason": "Why this is intentional" }
  ]
}

Or inline in your CDK code:

Validations.of(scope).acknowledge({
  id: 'cdk-insights::autoscaling-group-no-elb-healthcheck',
  reason: 'Why this is intentional',
});

Use the rule ID autoscaling-group-no-elb-healthcheck shown above — not the CDK-* ID from SARIF / GitHub code scanning. To dismiss every finding on one construct instead, use ignorePaths. Suppression docs →

More Auto Scaling rules