Lambda Function Code.FromBucket() does not update "Code Entry Type" in AWS console

[sacag]

Description

When CDK stack with Lambda function with property Code.FromBucket(..) is used, then the lambda when deployed for the first time, works fine. When an update to lambda is made and then the stack deploy is not updating the deployed lambda in console. It has the old code in AWS console. S3 bucket does have the latest changes. Reason being the "Code entry type" is not pointing to S3 for the lambda in AWS console?

Reproduction Steps

Error Log

Environment

• CLI Version :
• Framework Version:
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Other

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This is 🐛 Bug Report

[nija-at]

This beahviour is coming from CloudFormation and the behaviour of updates.

Quoting from https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/cfn-whatis-howdoesitwork.html#w2ab1b5c17c17 - "CloudFormation compares the modified template with the original template and generates a change set. The change set lists the proposed changes. After reviewing the changes, you can execute the change set to update your stack or you can create a new change set. "

Since the updated template your deployed did not change any values in AWS::Lambda::Function, CloudFormation will not make any updates to the Lambda function.

To achieve the behaviour you want, there are two options, either

1. manage your lambda code via the CDK using Code.fromAsset() where the code will be uploaded to S3 by the CDK when you run cdk deploy or,
2. specify the objectVersion property in Code.fromBucket() - in which case this property needs to be updated whenever the stack is deployed after the lambda function code is updated.

[Simonl9l]

@nija-at per the Code.fromBucket(() and using the objectVersion - do you have any recommendation on how to retrieve a given objects version such that it can be passed to this method.

Would you recommend using S3Client API to retrieve the latest version ?
Is there a more CDK centric way to do this ?

I assume it's better to pass in parameter or context value to the cdk deploy?

Also any approach has to be C# compatible It's my implementation scenario!

Additional it would be great if the "terse" (possibly generated) documentation noted the constrains and need to use versioning.

[marc-guenther]

So basically this means that:

• Code.fromBucket() is completely useless,
• that fact is not documented anywhere,
• this issue exists since at least two years, and
• it has been closed without even considering to fix it...

Wow!