cloudformation-diff: Hidden dependency on aws-sdk

[frankpengau]

Describe the bug

We have a custom aws-cdk consruct library that exports cloudformation-diff.

Since @aws-cdk/cloudformation-diff for version 2.119.0, it is throwing the following error:

node_modules/@aws-cdk/cloudformation-diff/lib/diff-template.d.ts:1:32 - error TS2307: Cannot find module 'aws-sdk' or its corresponding type declarations.

1 import { CloudFormation } from 'aws-sdk';
                                 ~~~~~~~~~


Found 1 error in node_modules/@aws-cdk/cloudformation-diff/lib/diff-template.d.ts:1

We believe the error is coming from changes in this PR: #28336

Specifically in packages/@aws-cdk/cloudformation-diff/lib/diff-template.ts, the following change:

// The SDK is only used to reference `DescribeChangeSetOutput`, so the SDK is added as a devDependency.
// The SDK should not make network calls here
// eslint-disable-next-line import/no-extraneous-dependencies
import { CloudFormation } from 'aws-sdk';

I have a sample repo to reproduce the exact issue: https://github.com/frankpengau/cdk-lib-cfn-diff-issue-20240112

Expected Behavior

It should not have a missing dependency.

Current Behavior

It currently has an indirect dependency on aws-sdk causing our construct library to have a transitive dependency on aws-sdk. If it is indeed a dependency, it should be added in as such, instead of being only a devdependency.

Reproduction Steps

1. cdk init lib --language typescript
2. Install @aws-cdk/cloudformation-diff for version 2.119.0
3. In a new file in lib folder: export * as cfndiff from @aws-cdk/cloudformation-diff
4. Compile typescript tsc

Possible Solution

Explicit dependency on aws-sdk, so that it shows up in the package-lock.json file and installs it as necessary for @aws-cdk/cloudformation-diff to work.

Additional Information/Context

No response

CDK CLI Version

2.114.1

Framework Version

No response

Node.js Version

18.13.0

OS

macOS

Language

TypeScript

Language Version

TypeScript (5.2.2)

Other information

No response

[pahud]

Thank you for the report. We will review the implementation in your PR.

[github-actions]

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