AWS CDK StateMachine BatchSubmitJob with dynamic environment variables - aws-cdk

Question

I'm trying to create a statemachine with a BatchSubmitJob in AWS CDK with dynamic environment variables in the BatchContainerOverrides. I was thinking about something like this:
container_overrides = sfn_tasks.BatchContainerOverrides(
environment={
"TEST.$": "$.dynamic_from_payload"
}
)
return sfn_tasks.BatchSubmitJob(self.scope,
id="id",
job_name="name",
job_definition_arn="arn",
job_queue_arn="arn",
container_overrides=container_overrides,
payload=sfn.TaskInput.from_object({
"dynamic_from_payload.$": "$.input.some_variable"
}))
However, upon deployment, CDK will add "Name" and "Value" to the statemachine definition, but Value is now static. This is part of the statemachine definition as seen in the console:
"Environment": [
{
"Name": "TEST.$",
"Value": "$.dynamic_from_payload"
}
]
But I need to have it like this:
"Environment": [
{
"Name": "TEST",
"Value.$": "$.dynamic_from_payload"
}
]
I also tried using "Ref::", as done here for the command parameters: AWS Step and Batch Dynamic Command. But this doesn't work either.
I also looked into escape hatches, overwriting the CloudFormation template. But I don't think that is applicable here, since the generated statemachine definition string is basically one large string.
I can think of two solutions, both of which don't make me happy: override the statemachine definition string with escape hatches with a copy in which "Value" is replaced on certain conditions (probably with regex) OR put a lambda in the statemachine that will create and trigger the batch job and a lambda that will poll if the job is finished.
Long story short: Does anyone have an idea of how to use dynamic environment variables with a BatchSubmitJob in CDK?

Answer 1

You can use the aws_cdk.aws_stepfunctions.JsonPath class:
container_overrides = sfn_tasks.BatchContainerOverrides(
environment={
"TEST": sfn.JsonPath.string_at("$.dynamic_from_payload")
}
)

Answer 2

Solved thanks to K. Galens!
I ended up with a Pass state with intrinsic functions to format the value and the aws_cdk.aws_stepfunctions.JsonPath for the BatchSubmitJob.
So something like this:
sfn.Pass(scope
id="id",
result_path="$.result",
parameters={"dynamic_from_payload.$": "States.Format('static_sub_part/{}',$.dynamic_sub_part)"} )
...
container_overrides = sfn_tasks.BatchContainerOverrides(
environment={
"TEST": sfn.JsonPath.string_at("$.result.dynamic_from_payload")
}
)