feat(gen2-migration): generate code for non-JS Lambda functions

[sharonyajain]

Description of changes

Resolves #14535 — gen2-migration generate now produces Gen2 code for non-JS Lambda functions (Python, Go, Java, .NET, Ruby) instead of throwing or skipping them.

Previously, the generate command only supported Node.js runtimes. PR #14744 added a skip path (via --skip-validations), but left users to hand-code the Gen2 definition. This PR completes the feature by generating the full resource.ts using Gen2's custom functions pattern.

What it generates (example for Python):

import { execSync } from 'node:child_process';
import * as path from 'node:path';
import { fileURLToPath } from 'node:url';
import { defineFunction } from '@aws-amplify/backend';
import { DockerImage, Duration } from 'aws-cdk-lib';
import { Code, Function, Runtime } from 'aws-cdk-lib/aws-lambda';

const functionDir = path.dirname(fileURLToPath(import.meta.url));

export const myPythonFunc = defineFunction(
  (scope) =>
    new Function(scope, 'myPythonFunc', {
      handler: 'index.handler',
      runtime: Runtime.PYTHON_3_11,
      timeout: Duration.seconds(20),
      memorySize: 256,
      code: Code.fromAsset(functionDir, {
        bundling: {
          image: DockerImage.fromRegistry('dummy'),
          local: {
            tryBundle(outputDir: string) {
              execSync(`python3 -m pip install ...`);
              execSync(`cp -r ...`);
              return true;
            },
          },
        },
      }),
    }),
);

Key changes:

• FunctionAssessor: All runtimes are now supported for generate (removed the isNonJsRuntime gate)
• FunctionRenderer: New renderCustomFunction() method emits the CDK Function construct pattern with runtime-specific bundling
• FunctionGenerator: Removed the throw for non-JS runtimes; branches into custom path when !runtime.startsWith('nodejs')
• copyFunctionSource: Preserves dependency files (requirements.txt, go.mod, pom.xml) for non-JS functions
• mapToCdkRuntime(): Maps Lambda runtime strings → CDK Runtime.* enum members

Runtime support:

Lambda Runtime	CDK Enum	Bundling
python3.x	PYTHON_3_X	pip install + copy
go1.x / provided.al2023	PROVIDED_AL2023	go build
java*	JAVA_*	mvn package
dotnet*	DOTNET_*	dotnet publish
ruby*	RUBY_*	copy

Issue #, if available

Closes #14535

Description of how you validated changes

• Runtime mapping unit tests (7 runtimes → correct CDK enum)
• Custom function rendering tests for Python, Go, Java, .NET
• Assessor tests updated: all runtimes pass validFor('generate')
• Manual verification of generated output matches Gen2 docs
• Pre-existing test for does not render runtime for non-nodejs still passes (Node.js path unchanged)

Checklist

• PR description included
• yarn test passes (gen2-migration tests)
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)
• New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies
• Pull request labels are added

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[Simone319]

CodeBuild Batch FAILED — Attempt 1

Batch: AmplifyCLI-PR-Testing:b5e4dc18-299d-4c87-b244-c74b7608ce7d
Source SHA: 268ade11e067737f26630d185833e3080808183d
Result: 2 of 17 build groups FAILED (15 succeeded)

❌ lint — FAILED

• 875 ESLint problems (0 errors, 875 warnings) were reported — not the direct blocker, since these are warnings.
• The actual failure comes from Prettier formatting check (Checking formatting...):

  [warn] packages/amplify-cli/src/__tests__/commands/gen2-migration/generate/amplify/function/function.renderer.test.ts
  [warn] packages/amplify-cli/src/commands/gen2-migration/generate/amplify/function/function.generator.ts
  [warn] packages/amplify-cli/src/commands/gen2-migration/generate/amplify/function/function.renderer.ts
  [warn] Code style issues found in 3 files. Forgot to run Prettier?
  

  → Command exited non-zero: source ./shared-scripts.sh && _lint (exit status 1)
• Fix: run yarn prettier --write (or equivalent repo lint-fix script) on those 3 files under packages/amplify-cli/src/commands/gen2-migration/generate/amplify/function/.

❌ verify_versions_match — FAILED

@aws-amplify/cli-internal version: 14.6.0-dev.268ade11e067737f26630d185833e3080808183d.0
@aws-amplify/cli version: 14.5.2-dev.268ade11e067737f26630d185833e3080808183d.0

• The dev-version bump for @aws-amplify/cli-internal (14.6.0) and @aws-amplify/cli (14.5.2) are out of sync — they must match.
• Tool's own guidance from the log:

  Manual fix: add a proper conventional commit that touches the amplify-cli-npm package to correct its version bump. Example: 15dcd96

---

Reported automatically from the CodeBuild batch run above. Commit status AWS CodeBuild BuildBatch us-east-1 (AmplifyCLI-PR-Testing) has been set to failure.

[Simone319]

Thanks for this — the runtime-mapping coverage and the dependency-manifest preservation are nice touches. One overall question before this is mergeable: has the generated output been deployed and invoked end-to-end for at least one non-JS runtime (e.g. run gen2-migration generate on a Python or Go function, then npx ampx sandbox and a live invoke)? The validation listed is at the transformer/schema level, and several of the inline points below (the Go bootstrap handler, the dropped env vars/permissions, the dummy bundling image) would only surface at deploy/runtime — a single real deploy would confirm the generated function actually stands up.

[sharonyajain]

On the end-to-end verification question: no — the generated output has not yet been deployed and invoked live for a non-JS runtime. Verification so far is unit/renderer-level (46 function-suite tests, 450 gen2-migration tests, prettier + version-match green). A real gen2-migration generate → npx ampx sandbox → live invoke on a Python/Go function needs an AWS account and a non-JS Gen1 app, which I haven't run.

Flagging this as the open manual-verification item. The inline fixes just pushed (env vars, forced Go bootstrap handler, real bundling image, loud warning for unknown runtimes) are exactly the things a live deploy would most likely have surfaced, so they narrow the risk — but a maintainer live pass (or a sandbox account to use) is still the right gate before merge. Head is now d35e8cfe0a.