(stepfunctions): Support for JSON Path in maxConcurrency field of step function map step

[jstag711]

Describe the feature

I would like to use a Json path to specify the max concurrency for my map task in my step function. Presently you must give it a fixed integer.

Use Case

I have a use case where I would like to specify the max concurrency as input to my step function so that I can change that without re-deploying my step function definition.

Proposed Solution

Allow JSON path for max concurrency

Other Information

No response

Acknowledgements

• I may be able to implement this feature request
• This feature might incur a breaking change

CDK version used

1.152.0

Environment details (OS name and version, etc.)

MacOS 10.15.7

[kaizencc]

Hi @jstag711! Can you try using JsonPath.numberAt('$.Field')?

[jstag711]

This is what I tried, it fails to synth:

Exception in thread "main" software.amazon.jsii.JsiiException: Validation failed with the following errors: maxConcurrency has to be a positive integer

Code:

software.amazon.awscdk.services.stepfunctions.Map batchRedrawTasks = new software.amazon.awscdk.services.stepfunctions.Map(this, "ConcurrentRedrawTasks",
                MapProps.builder()
                        .maxConcurrency(JsonPath.numberAt("$.maxConcurrency"))
                        .itemsPath(JsonPath.stringAt("$.batchParams"))
                        .parameters(Map.of(TASK_PARAMS + ".$", "$$.Map.Item.Value"))
                        .build());

[kaizencc]

Ah. Looks like an aggressive synth time check that did not account for jsonPaths. I'll try to fix this today.

[jstag711]

How should the numbers finally be expressed in the state machine definition? When I try manually editing it in the console to be this, it also complains: "MaxConcurrency": "$.maxConcurrency"

[github-actions]

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