(aws-ecs-patterns): QueueProcessingServiceBase does not respect a minScalingCapacity: 0

[wittekm]

In the following code:

aws-cdk/packages/@aws-cdk/aws-ecs-patterns/lib/base/queue-processing-service-base.ts

Line 312 in 75c96d7

} else {

I am in a situation where:

• I have turned on this.node.setContext(cxapi.ECS_REMOVE_DEFAULT_DESIRED_COUNT, true); (putting me in the else-else clause on line 312)
• I am creating a new ecs_patterns.QueueProcessingFargateService
• I'm feeding in a props.minScalingCapacity of 0 - which appears to be a completely valid number when using the ECS UI - but that is being overridden by the || 1

Reproduction Steps

Described reasonably well above. Create a new ecs_patterns.QueueProcessingFargateService with minScalingCapacity: 0 and inspect the generated Cfn template; it'll show a non-zero for MinCapacity. In my case:

    "apr23sysmongeneratorserviceQueueProcessingFargateServiceTaskCountTargetAE4E3513": {
      "Type": "AWS::ApplicationAutoScaling::ScalableTarget",
      "Properties": {
        "MaxCapacity": 5,
        "MinCapacity": 1,
        "ResourceId": {

What did you expect to happen?

Create a Cfn AWS::ApplicationAutoScaling::ScalableTarget with MinCapacity: 0

What actually happened?

Created a Cfn AWS::ApplicationAutoScaling::ScalableTarget with MinCapacity: 1

Environment

• Framework Version: 1.97.0

Other

Suggested solution:
Consider using = props.minScalingCapacity ?? 1 - this is the new Typescript Nullish Coalescing Operator, which slightly differs from || in that it will accept values like 0 and false, instead of falling through to the backup.

In general, you'd probably want to do a serious audit of all uses of x = x || y in cases where, say, 0 is a valid prop.

---

This is 🐛 Bug Report

[wimax-grapl]

As a workaround, it looks like I can piggyback on the || props.desiredTaskCount on 309, and set that to zero as well.

[github-actions]

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