aws-elasticloadbalancingv2: Incorrect hardcoded maximum load balancer `minimumCapacityUnit`

[jjant]

Describe the bug

The minimumCapacityUnit has a hardcoded limit of 1500 units:

aws-cdk/packages/aws-cdk-lib/aws-elasticloadbalancingv2/lib/alb/application-load-balancer.ts

Lines 198 to 205 in d8e6c09

	const minimumCapacityUnit = props.minimumCapacityUnit;
	if (
	minimumCapacityUnit &&
	!Token.isUnresolved(minimumCapacityUnit) &&
	(!Number.isInteger(minimumCapacityUnit) || minimumCapacityUnit < 100 || minimumCapacityUnit > 1500)
	) {
	throw new ValidationError(`'minimumCapacityUnit' must be a positive integer between 100 and 1500 for Application Load Balancer, got: ${minimumCapacityUnit}.`, this);
	}

This is incorrect. This is a soft limit that can be increased, see documentation:

Load Balancer Capacity Units

The following quotas are for Load Balancer Capacity Units (LCU).

Name	Default	Adjustable
Reserved Application Load Balancer Capacity Units (LCUs) per Application Load Balancer	1500	Yes
Reserved Application Load Balancer Capacity Units (LCU) per Region	0	Yes

Regression Issue

• Select this option if this issue appears to be a regression.

Last Known Working CDK Library Version

No response

Expected Behavior

The library doesn't error out when you set a higher minimumCapacityUnit than 1500.

Current Behavior

It errors out.

Reproduction Steps

new ApplicationLoadBalancer(this, "LoadBalancer", {
  // ... params
  minimumCapacityUnit: 1501
})

Possible Solution

Remove the limit

Additional Information/Context

No response

AWS CDK Library version (aws-cdk-lib)

2.191.0

AWS CDK CLI version

2.1011.0

Node.js Version

20

OS

OSX

Language

TypeScript

Language Version

No response

Other information

No response

[pahud]

Hi @jjant,

Thank you for reporting this issue. You are correct that the hardcoded maximum limit of 1500 for minimumCapacityUnit is incorrect, as this is a soft limit that can be increased through AWS Service Quotas.

The current validation in ApplicationLoadBalancer incorrectly enforces this as a hard limit.

We should modify the validation to only check:

• Value is a positive integer
• Value is >= 100 (minimum requirement)

Would you be interested in contributing a fix for this? The change would involve updating the validation logic in the ApplicationLoadBalancer constructor.

If you'd like to contribute, here's what needs to be changed:

1. Remove the upper limit check (minimumCapacityUnit > 1500)
2. Update the error message to only mention the minimum requirement

[github-actions]

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