aws-lambda-nodejs/lib/bundlingts.ts: Missing condition when checking for v2 runtime

[Minh-Duc-Ng]

Describe the bug

Hi,

I have been receiving weird warnings from aws cdk about nodejs runtime since upgrading to v2.93.

When creating new NodejsFunction, I make sure to pass runtime: Runtime.NODEJS_16_X as one of the props. However, I still get this warning: "If you are relying on AWS SDK v2 to be present in the Lambda environment already, please explicitly configure a NodeJS runtime of Node 16 or lower".

My company requires all cdk deployment to be executed with strict-mode so we can't ignore this warning.

Expected Behavior

No warning raised by cdk because I am specifying Nodejs 16 or lower as instructed

Current Behavior

A warning is raised whenever I create a NodejsFunction with runtime: Runtime.NODEJS_16_X

Reproduction Steps

Run cdk synth to create following resource:

const lambda = new NodejsFunction(this, 'id', {
      entry: join(__dirname, "..", "lambdas", "lambda.ts"),
      handler: "handler",
      timeout: Duration.minutes(3),
      functionName: lambdaFnName,
      runtime: Runtime.NODEJS_16_X,
      memorySize: 512,
      depsLockFilePath: join(__dirname, "..", "..", "..", "..", "pnpm-lock.yaml"),
      role: lambdaExecutionRole,
      logRetention: RetentionDays.TWO_WEEKS,
    });

Possible Solution

I believe this is the code section that cause the warning:

https://github.com/aws/aws-cdk/blob/d6b71adb41cb2cccf30e2301f872806e12ad4a87/packages/aws-cdk-lib/aws-lambda-nodejs/lib/bundling.ts#L127C5-L143C1

// Modules to externalize when using a constant known version of the runtime.
    // Mark aws-sdk as external by default (available in the runtime)
    const isV2Runtime = isSdkV2Runtime(props.runtime);
    const versionedExternals = isV2Runtime ? ['aws-sdk'] : ['@aws-sdk/*'];
    // Don't automatically externalize any dependencies when using a `latest` runtime which may
    // update versions in the future.
    const defaultExternals = props.runtime?.isVariable ? [] : versionedExternals;
    const externals = props.externalModules ?? defaultExternals;

    // Warn users if they are trying to rely on global versions of the SDK that aren't available in
    // their environment.
    if (isV2Runtime && externals.some((pkgName) => pkgName.startsWith('@aws-sdk/'))) {
      cdk.Annotations.of(scope).addWarningV2('@aws-cdk/aws-lambda-nodejs:sdkV3NotInRuntime', 'If you are relying on AWS SDK v3 to be present in the Lambda environment already, please explicitly configure a NodeJS runtime of Node 18 or higher.');
    } else if (externals.includes('aws-sdk')) {
      cdk.Annotations.of(scope).addWarningV2('@aws-cdk/aws-lambda-nodejs:sdkV2NotInRuntime', 'If you are relying on AWS SDK v2 to be present in the Lambda environment already, please explicitly configure a NodeJS runtime of Node 16 or lower.');
    }

If someone pass runtime: Runtime.NODEJS_16_X and no externalModules provided like my example above
-> isV2Runtime is True -> versionedExternals = ['aws-sdk'] -> defaultExternals = ['aws-sdk'] -> externals = ['aws-sdk']
-> the condition if (externals.includes('aws-sdk')) on line 140 is true
-> warning message displayed

Possible fix: adding more condition to line 140: if (!isV2Runtime && externals.includes('aws-sdk'))

Additional Information/Context

No response

CDK CLI Version

2.93.0

Framework Version

No response

Node.js Version

16

OS

Ubuntu

Language

Typescript

Language Version

No response

Other information

No response

[plumdog]

I also encountered this issue and agree with the investigation above that the logic around generating the warning is invalid.

Have opened #27014 to attempt to fix and write some tests.

[github-actions]

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[Minh-Duc-Ng]

Hi @plumdog, thank you for looking into this issue. I realize my proposed solutions might not be correct in some cases, such that the user specify Runtime.NODEJS_18_X in NodejsFunction, and then follow the warning instruction to add a 'aws-sdk' as external modules -> the warning is still going to be there.

Honestly, I am not sure about the wording of this warning. Is it allowed for someone to use Nodejs 18 and request 'aws-sdk' as external modules like my example above? If not, maybe the warning should tell the dev to upgrade their code to use sdk v3.