fix(autoscaling): step scaling without adjustment type fails

[go-to-k]

Reason for this change

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,
});

Description of changes

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).

The documentation also says that the default value is CHANGE_IN_CAPACITY.

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,

The fact that the error occurs if props.adjustmentType is not specified means that the user's successful existing stack always specifies props.adjustmentType. In other words, no change to the existing resource will occur due to this change, so there is no need for a feature flag.

Description of how you validated changes

Unit tests without integ tests, because this PR could cover this bug by unit tests.
Both unit and integ tests.

Checklist

• My code adheres to the CONTRIBUTING GUIDE and DESIGN GUIDELINES

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license

[go-to-k]

The property is defined here.

[go-to-k]

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

I could change an integ test and snapshots

[aws-cdk-automation]

The pull request linter has failed. See the aws-cdk-automation comment below for failure reasons. If you believe this pull request should receive an exemption, please comment and provide a justification.

A comment requesting an exemption should contain the text Exemption Request. Additionally, if clarification is needed add Clarification Request to a comment.

✅ Updated pull request passes all PRLinter validations. Dismissing previous PRLinter review.

[lpizzinidev]

Looks good to me 👍

[GavinZZ]

LGTM, thanks for contributing

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).

[aws-cdk-automation]

AWS CodeBuild CI Report

• CodeBuild project: AutoBuildv2Project1C6BFA3F-wQm2hXv2jqQv
• Commit ID: c40ab28
• Result: SUCCEEDED
• Build Logs (available for 30 days)

Powered by github-codebuild-logs, available on the AWS Serverless Application Repository