(lambda): Remove requirement to call currentVersion in order for currentVersionOptions to take effect

[SamStephens]

Describe the bug

As per #13731, specifying currentVersionOptions for a Function has no effect unless currentVersion is invoked.

It's easy to see why this is with cdk diff, because these options actually apply to a brand new AWS::Lambda::Version resource that doesn't exist unless currentVersion is invoked. But it's a confusing behavior, and there doesn't seem to be any scenario where a user would specify currentVersionOptions for a Function and not want a AWS::Lambda::Version resource to be created with those options.

Expected Behavior

Specifying currentVersionOptions to provide options for the current version of the Lambda Function without any subsequent interaction being required.

Current Behavior

Specifying currentVersionOptions for a Function has no effect unless the currentVersion method is called.

Reproduction Steps

(Copied from #13731).

export class LambdaAutoScalingStack extends cdk.Stack {
    constructor(scope: cdk.App, id: string) {
        super(scope, id);

        new lambda.Function(this, 'lambda1', {
            code: new lambda.InlineCode('exports.handler = async () => { console.log(\'hello world\'); };'),
            handler: 'index.handler',
            runtime: lambda.Runtime.NODEJS_10_X,
            currentVersionOptions: {
                provisionedConcurrentExecutions: 3
            }
        })

    }
}

Does not configure provisioned concurrency for the current version of the function.

export class LambdaAutoScalingStack extends cdk.Stack {
    constructor(scope: cdk.App, id: string) {
        super(scope, id);

        new lambda.Function(this, 'lambda1', {
            code: new lambda.InlineCode('exports.handler = async () => { console.log(\'hello world\'); };'),
            handler: 'index.handler',
            runtime: lambda.Runtime.NODEJS_10_X,
            currentVersionOptions: {
                provisionedConcurrentExecutions: 3
            }
        });
        fn.currentVersion;

    }
}

Does configure provisioned concurrency for the current version of the function.

Possible Solution

Possibly, just something simply like implicitly calling currentVersion in the constructor if currentVersionOptions is not null.

Additional Information/Context

No response

CDK CLI Version

2.48.0

Framework Version

No response

Node.js Version

v16.15.1

OS

Ubuntu (Windows Subsystem for Linux)

Language

Typescript, Python, .NET, Java, Go

Language Version

No response

Other information

No response

[peterwoodworth]

I think it sounds reasonable to create a current version if currentVersionOptions are supplied. Thanks for the feature request

I am marking this issue as p2, which means that we are unable to work on this immediately.

We use +1s to help prioritize our work, and are happy to revaluate this issue based on community feedback. You can reach out to the cdk.dev community on Slack to solicit support for reprioritization.

Check out our contributing guide if you're interested in contributing yourself - there's a low chance the team will be able to address this soon but we'd try to take a look at a PR

[github-actions]

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[SamStephens]

The fix for this was reverted by #23636, as the original fix

breaks the case where a user both:

• Specifies currentVersionOptions
• Never calls currentVersion but instead creates a Version object directly.

In that case, 2 Version resources are created, but the second one fails because Lambda will not allow creating a new Version if nothing changed since the last Version.