fix(autoscaling): step scaling without adjustment type fails

[go-to-k]

Step Scaling without adjustmentType fails with CFn error You must specify an AdjustmentType for policy type: StepScaling.

• Reproduction code

const asg = new autoscaling.AutoScalingGroup(stack, 'ASG', {
  vpc,
  instanceType: ec2.InstanceType.of(ec2.InstanceClass.BURSTABLE2, ec2.InstanceSize.MICRO),
  machineImage: new ec2.AmazonLinuxImage({ generation: ec2.AmazonLinuxGeneration.AMAZON_LINUX_2 }),
});

asg.scaleOnMetric('StepScaling', {
  metric: new cloudwatch.Metric({ namespace: 'AWS/EC2', metricName: 'CPUUtilization', dimensionsMap: { AutoScalingGroupName: asg.autoScalingGroupName } }),
  scalingSteps: [
    { upper: 10, change: -1 },
    { lower: 50, change: +1 },
    { lower: 90, change: +2 },
  ],
  evaluationPeriods: 10,
  datapointsToAlarm: 5,
  metricAggregationType: autoscaling.MetricAggregationType.MAXIMUM,

  // adjustmentType: autoscaling.AdjustmentType.CHANGE_IN_CAPACITY,
});

According to the CDK code, CHANGE_IN_CAPACITY will be used if adjustmentType is not specified in the prop. But the variable is not passed into StepScalingAction construct (instead props.adjustmentType is passed as is).

So we should use adjustmentType instead of props.adjustmentType.

    const adjustmentType = props.adjustmentType || AdjustmentType.CHANGE_IN_CAPACITY;
    const changesAreAbsolute = adjustmentType === AdjustmentType.EXACT_CAPACITY;
    // ...
    // ...

      this.lowerAction = new StepScalingAction(this, 'LowerPolicy', {
        // adjustmentType: props.adjustmentType,
        adjustmentType,

---

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[go-to-k]

Exemption Request: This PR could cover this bug by unit tests.

[go-to-k]

The property is defined here.

[aws-cdk-automation]

This PR has been in the CHANGES REQUESTED state for 3 weeks, and looks abandoned. To keep this PR from being closed, please continue work on it. If not, it will automatically be closed in a week.

[go-to-k]

Exemption Request: #28794 (comment)

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: 5392611
• Result: SUCCEEDED
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[aws-cdk-automation]

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[mergify]

⚠️ The sha of the head commit of this PR conflicts with #29158. Mergify cannot evaluate rules on this PR. ⚠️