(EvaluateExpression): The logical id of lambda created by EvaluateExpression changed after nodejs upgrade.

[weididai]

Describe the bug

We recently encountered a issue that the logical id of lambda created by EvaluateExpression changed after nodejs upgrade. This resulted in a new lambda got created and the old lambda got deleted which caused some impact. Upon some investigation, we discovered that is because the logical id of lambda created by EvaluateExpression is determined by nodejs version -- https://github.com/aws/aws-cdk/blob/v2.120.0/packages/aws-cdk-lib/aws-stepfunctions-tasks/lib/evaluate-expression.ts#L114. Is there a workaround here to do a nodejs upgrade without changing the logical id of the lambda.

We already tried using the overrideLogicalId but it seems the overrideLogicalId does not support for lambda created by EvaluateExpression

Expected Behavior

The logical id of lambda created by EvaluateExpression should not change after nodejs upgrade.

Current Behavior

The logical id of lambda created by EvaluateExpression is changed after nodejs upgrade.

Reproduction Steps

1. Use nodejs 14.x for the EvaluateExpression and check the logical id of the lambda generated.
2. Change the nodejs version to 18.x and then check the logical id of the lambda generated.
3. The logical id generated from step 2 is different from step 1

Possible Solution

1. Support overrideLogicalId of the lambda created by EvaluateExpression
2. Only use the nodejs version to generate logical id if two EvaluateExpression have different nodejs version under the same path.

Additional Information/Context

No response

CDK CLI Version

2.120.0

Framework Version

No response

Node.js Version

14.x

OS

linux

Language

TypeScript

Language Version

No response

Other information

No response

[pahud]

Yes I can confirm it does change when updating the runtime. This could be related to #28251. Making it a p1.

[colifran]

I don't think this is related to #28251. To me it appears that this is the intended behavior. We have an object nodeJsGuids which contains nodejs runtimes as keys and a uuid as a value. A SingletonFunction looks through the construct tree to see if a function with the same uuid already exists in the same scope and won't create a new one if it does. Since we're updating the uuid when we update the runtime I would expect a new function to be created and the old one to be deleted. That's not to say we couldn't support the proposed behavior, though.

[weididai]

Thanks colifran, I understand this might be the intended behavior since we want to have different lambda created for different nodejs version. Currently, there is no way that I realize that could upgrade the nodejs version without updating the logical id of lambda. So I think team could give a workaround here by supporting overrideLogicalId of the lambda created by EvaluateExpression.

[pahud]

From my test, simply updating the runtime would not change the lambda.Function logicalId.

For example, change the runtime from NODEJS_16_X to NODEJS_18_X would only have in-place update:

    new lambda.Function(this, 'Func', {
        code: lambda.Code.fromInline('mock'),
        handler: 'index.handler',
        runtime: lambda.Runtime.NODEJS_16_X,
    });

But changing the runtime for EvaluateExpression would trigger Function and Role replacement:

const task = new tasks.EvaluateExpression(this, 'Task', {
  expression: '$.a + $.b',
  runtime: lambda.Runtime.NODEJS_16_X,
});

I am guessing it's EvalNodejsSingletonFunction that returns new resources.

Wondering it might because EvalNodejsSingletonFunction is actually a SingletonFunction which always ensureLambda based on given props and generate different constructName here, hence generating a new lambda.Function with different id from here.

I guess it's by design how SingletonFunction works when we pass a new uuid, CDK would always create a new lambda.Function by replacing the existing one and it's how it works now.

@weididai What is the impact if the lambda.Function would be replaced with a new logicalId? Can you share more about that?

[weididai]

The logical id of the lambda created by EvaluateExpression is changed during a long running step function. Thus the step function fails as it tries to invoke the old lambda but the old lambda was already destroyed.

[pahud]

@weididai Thank you for your report I think we should figure out a way to avoid that as updating a SingletonFunction would always change the logicalId.

[pahud]

Hi @weididai

Consider this sample:

export class DummyStack extends Stack {
  constructor(scope: Construct, id: string, props: StackProps) {
    super(scope, id, props);

    const expression = new tasks.EvaluateExpression(this, 'Task', {
      expression: '$.a + $.b',
      runtime: lambda.Runtime.NODEJS_16_X
    });

    this.overrideLambdaLogicalId('Evalda2d1181604e4a4586941a6abd7fe42dF371675D')

  }

  private overrideLambdaLogicalId(logicalId: string) {
    this.node.findAll().filter((construct) => 
    construct.node.id.startsWith('Eval') && (construct.node.defaultChild instanceof lambda.CfnFunction))
    .forEach(x => {
      (x.node.defaultChild as lambda.CfnFunction).overrideLogicalId(logicalId);
    })
  }

}

If you change the runtime and run npx cdk diff you should see this, indicating the lambda Function would not be replaced.

Let me know if it works for you.

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