Handle CDK version mismatch

[sobolk]

Problem

When installed aws-cdk and aws-cdk-lib are not compatible a fault is raised.

Repro.

Create project like and use mismatched CDK versions.

{
  "name": "testapp048",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "@aws-amplify/backend": "^1.2.1",
    "@aws-amplify/backend-cli": "^1.2.6",
    "aws-cdk": "2.130.0",
    "aws-cdk-lib": "2.158.0",
    "constructs": "^10.3.0",
    "esbuild": "^0.23.1",
    "tsx": "^4.19.1",
    "typescript": "^5.6.2"
  },
  "dependencies": {
    "aws-amplify": "^6.6.1"
  }
}

Observe

Changes

Add mapping and classify as user error.

Validation

1. Added test.
2. Manual verification

Checklist

• If this PR includes a functional change to the runtime behavior of the code, I have added or updated automated test coverage for this change.
• If this PR requires a change to the Project Architecture README, I have included that update in this PR.
• If this PR requires a docs update, I have linked to that docs PR above.
• If this PR modifies E2E tests, makes changes to resource provisioning, or makes SDK calls, I have run the PR checks with the run-e2e label set.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[changeset-bot]

🦋 Changeset detected

Latest commit: a49a006

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@aws-amplify/backend-deployer	Patch

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[rtpascual]

LGTM. One question, so the only way customers run into this is if they update their package.json? We would have to keep a close eye to make sure this isn't unintentionally changed to have mismatched versions

amplify-backend/packages/create-amplify/src/amplify_project_creator.ts

Lines 18 to 19 in 5af7781

	'aws-cdk@^2',
	'aws-cdk-lib@^2',

[sobolk]

LGTM. One question, so the only way customers run into this is if they update their package.json? We would have to keep a close eye to make sure this isn't unintentionally changed to have mismatched versions

amplify-backend/packages/create-amplify/src/amplify_project_creator.ts

Lines 18 to 19 in 5af7781

	'aws-cdk@^2',
	'aws-cdk-lib@^2',

The other way would be to surgically npm update aws-cdk-lib without the other one. I.e. they won't get into this situation by following our create flow. The mismatch happens after create flow, by playing with package.json or npm commands.

As for us changing create flow to mismatched versions. This one is tricky to assert because as long as we ^ both versions the npm will install both at latest - which in theory is correct state.
We would grossly mess this up if we skip ^, but this would surface in e2e tests or canaries.