feat(custom-resources): AwsCustomResource copy physicalResourceId from request when omit it in onUpdate

[konokenj]

AwsCustomResource is now able to omit physicalResourceId in onUpdate to copy it from request.

Some UPDATE AWS APIs responses with an empty body. When users want to call these APIs using AwsCustomResource, users can't specify physicalResourceId by PhysicalResourceId.fromResponse(). Furthermore, when the Create API generates an unpredictable ID and this must be passed to the Update API, this Construct could not be used. For example, following APIs match this situation:

• https://docs.aws.amazon.com/athena/latest/APIReference/API_UpdateNotebook.html
• https://docs.aws.amazon.com/singlesignon/latest/IdentityStoreAPIReference/API_UpdateUser.html

Closes #23843.

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[comcalvi]

AwsCustomResource is now able to omit physicalResourceId in onUpdate with passthrough it from request. This is useful when users want to call an update API without resoure replacing.

I'm not sure what "passthrough it from request" means, could you please elaborate?

call an update API without resoure replacing.

I don't understand this either. Does it mean that today, it is impossible to call onUpdate without a replacement of the custom resource?

[konokenj]

Hi @comcalvi, thank you for response.

I'm not sure what "passthrough it from request" means, could you please elaborate?

Lambda backed custom resources recieves physicalResourceId in request event on update. The handler function has responsibility to return same physicalResourceId when the resource is not replaced.

The value returned for a PhysicalResourceId can change custom resource update operations. If the value returned is the same, it is considered a normal update. If the value returned is different, AWS CloudFormation recognizes the update as a replacement and sends a delete request to the old resource.

https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/crpg-ref-requesttypes-update.html

But currently, users of AwsCustomResource construct must specify physicalResourceId by hand (fromResponse() or .of()). There is no way to copy from request, although there are AWS APIs that response with empty bodies. This PR adds ability to copy that.

call an update API without resoure replacing.

I don't understand this either. Does it mean that today, it is impossible to call onUpdate without a replacement of the custom resource?

No, I intended to allow users to indicate their intention to copy PhysicalResourceId.

(I'm sorry if this is a problem caused by my poor English skill.)

[comcalvi]

To confirm, leaving the PhysicalResourceId undefined will tell CFN to use the value that was passed toonCreate? If so, this makes perfect sense. Please create a new unit test in test/aws-custom-resource that verifies the updated error checking logic you've added

Pull request has been modified.

[konokenj]

I added unit tests.

To confirm, leaving the PhysicalResourceId undefined will tell CFN to use the value that was passed to onCreate?

PhysicalResourceId is not rendered in CFn template when omit in onUpdate. When handler function doesn't recieve PhysicalResourceId from request, it uses previous value.

aws-cdk/packages/@aws-cdk/custom-resources/lib/aws-custom-resource/runtime/index.ts

Line 153 in 0ebbf58

physicalResourceId = event.ResourceProperties[event.RequestType]?.physicalResourceId?.id ?? event.PhysicalResourceId;

Pull request has been modified.

[konokenj]

I fixed code style and error messages. Could you review again?

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[mergify]

Thank you for contributing! Your pull request will be updated from main and then merged automatically (do not update manually, and be sure to allow changes to be pushed to your fork).