feat(cli-internal): allow generate to skip non-JS Lambda functions

iliapolo · iliapolo · commit 71ab7d1e3279 · 2026-04-02T14:49:01.000-04:00
Surface non-JS Lambda runtimes as unsupported in the assessment
rather than throwing at generation time. The FunctionAssessor now
reads the runtime from the local CloudFormation template and marks
the resource as unsupported for generate when it is not Node.js.

The generate orchestrator checks assessment.of(resource, step)
before entering the switch, skipping any resource that is not
supported. This means --skip-validations allows generation to
proceed while silently skipping non-JS functions.

Also adds Assessment.of(resource, step) which returns the support
level for a specific resource, usable by any step orchestrator.

Tested with unit tests covering Python, Java, dotnet runtimes,
Node.js as supported, and missing template as an error.
---
Prompt: Fix issue 14723 — `generate` should allow skipping
over non JS functions. These functions can later be hand coded
by the user. Instead of throwing an error, surface the
unsupported functions as part of the assessment validation —
this would allow --skip-validations to skip over this as well.
diff --git a/packages/amplify-cli/src/__tests__/commands/gen2-migration/assess.test.ts b/packages/amplify-cli/src/__tests__/commands/gen2-migration/assess.test.ts
@@ -9,11 +9,18 @@ function mockGen1App(resources: DiscoveredResource[], existingFiles: string[] =
     discover: () => resources,
     meta: () => undefined,
     fileExists: (path: string) => fileSet.has(path),
-    json: (path: string) => jsonFiles[path],
+    json: (path: string) => {
+      if (!(path in jsonFiles)) throw new Error(`File not found: ${path}`);
+      return jsonFiles[path];
+    },
     ensureCliInputs: () => undefined,
   } as unknown as Gen1App;
 }
 
+const NODEJS_TEMPLATE = {
+  Resources: { LambdaFunction: { Properties: { Runtime: 'nodejs18.x' } } },
+};
+
 describe('AmplifyMigrationAssessor', () => {
   describe('assess()', () => {
     it('returns empty assessment when no resources discovered', () => {
@@ -31,7 +38,10 @@ describe('AmplifyMigrationAssessor', () => {
       const gen1App = mockGen1App(
         [{ category: 'function', resourceName: 'myFunc', service: 'Lambda', key: 'function:Lambda' }],
         ['function/myFunc/custom-policies.json'],
-        { 'function/myFunc/custom-policies.json': [{ Action: ['s3:GetObject'], Resource: ['arn:aws:s3:::my-bucket/*'] }] },
+        {
+          'function/myFunc/myFunc-cloudformation-template.json': NODEJS_TEMPLATE,
+          'function/myFunc/custom-policies.json': [{ Action: ['s3:GetObject'], Resource: ['arn:aws:s3:::my-bucket/*'] }],
+        },
       );
       const assessor = new AmplifyMigrationAssessor(gen1App);
       const assessment = assessor.assess();
@@ -56,7 +66,10 @@ describe('AmplifyMigrationAssessor', () => {
       const gen1App = mockGen1App(
         [{ category: 'function', resourceName: 'myFunc', service: 'Lambda', key: 'function:Lambda' }],
         ['function/myFunc/custom-policies.json'],
-        { 'function/myFunc/custom-policies.json': [{ Action: [], Resource: [] }] },
+        {
+          'function/myFunc/myFunc-cloudformation-template.json': NODEJS_TEMPLATE,
+          'function/myFunc/custom-policies.json': [{ Action: [], Resource: [] }],
+        },
       );
       const assessor = new AmplifyMigrationAssessor(gen1App);
       const assessment = assessor.assess();
@@ -73,6 +86,26 @@ describe('AmplifyMigrationAssessor', () => {
       expect(assessment.resources[0].generate.level).toBe('unsupported');
       expect(assessment.resources[0].refactor.level).toBe('unsupported');
     });
+
+    it('marks function with non-JS runtime as unsupported for generate', () => {
+      const gen1App = mockGen1App(
+        [{ category: 'function', resourceName: 'myPythonFunc', service: 'Lambda', key: 'function:Lambda' }],
+        ['function/myPythonFunc/myPythonFunc-cloudformation-template.json'],
+        {
+          'function/myPythonFunc/myPythonFunc-cloudformation-template.json': {
+            Resources: { LambdaFunction: { Properties: { Runtime: 'python3.11' } } },
+          },
+        },
+      );
+      const assessor = new AmplifyMigrationAssessor(gen1App);
+      const assessment = assessor.assess();
+
+      expect(assessment.resources).toHaveLength(1);
+      expect(assessment.resources[0].generate.level).toBe('unsupported');
+      expect(assessment.resources[0].refactor.level).toBe('supported');
+      expect(assessment.validFor('generate')).toBe(false);
+      expect(assessment.validFor('refactor')).toBe(true);
+    });
   });
 
   describe('run()', () => {
diff --git a/packages/amplify-cli/src/__tests__/commands/gen2-migration/assess/function/function.assessor.test.ts b/packages/amplify-cli/src/__tests__/commands/gen2-migration/assess/function/function.assessor.test.ts
@@ -6,16 +6,25 @@ function mockGen1App(existingFiles: string[] = [], jsonFiles: Record<string, unk
   const fileSet = new Set(existingFiles);
   return {
     fileExists: (path: string) => fileSet.has(path),
-    json: (path: string) => jsonFiles[path],
+    json: (path: string) => {
+      if (!(path in jsonFiles)) throw new Error(`File not found: ${path}`);
+      return jsonFiles[path];
+    },
   } as unknown as Gen1App;
 }
 
+const NODEJS_TEMPLATE_PATH = 'function/myFunc/myFunc-cloudformation-template.json';
+const NODEJS_TEMPLATE = {
+  Resources: { LambdaFunction: { Properties: { Runtime: 'nodejs18.x' } } },
+};
+
 const RESOURCE: DiscoveredResource = { category: 'function', resourceName: 'myFunc', service: 'Lambda', key: 'function:Lambda' };
 
 describe('FunctionAssessor', () => {
   it('records resource as supported', () => {
+    const gen1App = mockGen1App([], { [NODEJS_TEMPLATE_PATH]: NODEJS_TEMPLATE });
     const assessment = new Assessment('app', 'dev');
-    new FunctionAssessor(mockGen1App(), RESOURCE).record(assessment);
+    new FunctionAssessor(gen1App, RESOURCE).record(assessment);
 
     const entry = assessment.resources[0];
     expect(entry!.generate.level).toBe('supported');
@@ -24,6 +33,7 @@ describe('FunctionAssessor', () => {
 
   it('detects non-empty custom-policies.json', () => {
     const gen1App = mockGen1App(['function/myFunc/custom-policies.json'], {
+      [NODEJS_TEMPLATE_PATH]: NODEJS_TEMPLATE,
       'function/myFunc/custom-policies.json': [{ Action: ['s3:GetObject'], Resource: ['arn:aws:s3:::bucket/*'] }],
     });
     const assessment = new Assessment('app', 'dev');
@@ -39,6 +49,7 @@ describe('FunctionAssessor', () => {
 
   it('ignores empty custom-policies.json', () => {
     const gen1App = mockGen1App(['function/myFunc/custom-policies.json'], {
+      [NODEJS_TEMPLATE_PATH]: NODEJS_TEMPLATE,
       'function/myFunc/custom-policies.json': [{ Action: [], Resource: [] }],
     });
     const assessment = new Assessment('app', 'dev');
@@ -48,9 +59,71 @@ describe('FunctionAssessor', () => {
   });
 
   it('records no features when custom-policies.json is absent', () => {
+    const gen1App = mockGen1App([], { [NODEJS_TEMPLATE_PATH]: NODEJS_TEMPLATE });
     const assessment = new Assessment('app', 'dev');
-    new FunctionAssessor(mockGen1App(), RESOURCE).record(assessment);
+    new FunctionAssessor(gen1App, RESOURCE).record(assessment);
 
     expect(assessment.features).toHaveLength(0);
   });
+
+  describe('non-JS runtime detection', () => {
+    it('marks resource as unsupported for generate when runtime is Python', () => {
+      const gen1App = mockGen1App(['function/myFunc/myFunc-cloudformation-template.json'], {
+        'function/myFunc/myFunc-cloudformation-template.json': {
+          Resources: { LambdaFunction: { Properties: { Runtime: 'python3.11' } } },
+        },
+      });
+      const assessment = new Assessment('app', 'dev');
+      new FunctionAssessor(gen1App, RESOURCE).record(assessment);
+
+      const entry = assessment.resources[0];
+      expect(entry!.generate.level).toBe('unsupported');
+      expect(entry!.generate.note).toContain('python3.11');
+      expect(entry!.refactor.level).toBe('supported');
+    });
+
+    it('records non-js-runtime as unsupported resource without feature entry', () => {
+      const gen1App = mockGen1App(['function/myFunc/myFunc-cloudformation-template.json'], {
+        'function/myFunc/myFunc-cloudformation-template.json': {
+          Resources: { LambdaFunction: { Properties: { Runtime: 'java21' } } },
+        },
+      });
+      const assessment = new Assessment('app', 'dev');
+      new FunctionAssessor(gen1App, RESOURCE).record(assessment);
+
+      expect(assessment.resources[0]!.generate.level).toBe('unsupported');
+      expect(assessment.features).toHaveLength(0);
+    });
+
+    it('fails assessment validFor generate when runtime is non-JS', () => {
+      const gen1App = mockGen1App(['function/myFunc/myFunc-cloudformation-template.json'], {
+        'function/myFunc/myFunc-cloudformation-template.json': {
+          Resources: { LambdaFunction: { Properties: { Runtime: 'dotnet8' } } },
+        },
+      });
+      const assessment = new Assessment('app', 'dev');
+      new FunctionAssessor(gen1App, RESOURCE).record(assessment);
+
+      expect(assessment.validFor('generate')).toBe(false);
+      expect(assessment.validFor('refactor')).toBe(true);
+    });
+
+    it('treats nodejs runtimes as supported', () => {
+      const gen1App = mockGen1App(['function/myFunc/myFunc-cloudformation-template.json'], {
+        'function/myFunc/myFunc-cloudformation-template.json': {
+          Resources: { LambdaFunction: { Properties: { Runtime: 'nodejs18.x' } } },
+        },
+      });
+      const assessment = new Assessment('app', 'dev');
+      new FunctionAssessor(gen1App, RESOURCE).record(assessment);
+
+      expect(assessment.resources[0]!.generate.level).toBe('supported');
+      expect(assessment.features).toHaveLength(0);
+    });
+
+    it('throws when CloudFormation template is missing', () => {
+      const assessment = new Assessment('app', 'dev');
+      expect(() => new FunctionAssessor(mockGen1App(), RESOURCE).record(assessment)).toThrow();
+    });
+  });
 });
diff --git a/packages/amplify-cli/src/commands/gen2-migration/assess/assessment.ts b/packages/amplify-cli/src/commands/gen2-migration/assess/assessment.ts
@@ -98,6 +98,25 @@ export class Assessment {
     return this._features;
   }
 
+  /**
+   * Returns the support level for a specific resource in the given step.
+   */
+  // eslint-disable-next-line consistent-return -- exhaustive switch; compiler enforces all cases
+  public of(resource: DiscoveredResource, step: 'generate' | 'refactor'): Support {
+    const entry = this._resources.find(
+      (ra) => ra.resource.category === resource.category && ra.resource.resourceName === resource.resourceName,
+    );
+    if (!entry) {
+      return supported();
+    }
+    switch (step) {
+      case 'generate':
+        return entry.generate;
+      case 'refactor':
+        return entry.refactor;
+    }
+  }
+
   /**
    * Returns true if all resources and features are supported for the given step.
    */
diff --git a/packages/amplify-cli/src/commands/gen2-migration/assess/function/function.assessor.ts b/packages/amplify-cli/src/commands/gen2-migration/assess/function/function.assessor.ts
@@ -4,7 +4,7 @@ import { Gen1App, DiscoveredResource, KNOWN_FEATURES } from '../../generate/_inf
 
 /**
  * Assesses migration readiness for a single Lambda function resource.
- * Detects custom-policies.json usage.
+ * Detects non-JS runtimes and custom-policies.json usage.
  */
 export class FunctionAssessor implements Assessor {
   public constructor(private readonly gen1App: Gen1App, private readonly resource: DiscoveredResource) {}
@@ -13,9 +13,13 @@ export class FunctionAssessor implements Assessor {
    * Records resource-level and feature-level support for this function.
    */
   public record(assessment: Assessment): void {
+    const templatePath = `function/${this.resource.resourceName}/${this.resource.resourceName}-cloudformation-template.json`;
+    const template = this.gen1App.json(templatePath);
+    const runtime: string | undefined = template?.Resources?.LambdaFunction?.Properties?.Runtime;
+
     assessment.recordResource({
       resource: this.resource,
-      generate: supported(),
+      generate: this.isNonJsRuntime(runtime) ? unsupported(`uses non-JS runtime '${runtime}'`) : supported(),
       refactor: supported(),
     });
 
@@ -30,6 +34,13 @@ export class FunctionAssessor implements Assessor {
     }
   }
 
+  /**
+   * Returns true if the runtime is present and is not a Node.js variant.
+   */
+  private isNonJsRuntime(runtime: string | undefined): boolean {
+    return runtime !== undefined && !runtime.startsWith('nodejs');
+  }
+
   /**
    * Returns true if the function has non-empty custom policies.
    * The file always exists but defaults to `[{"Action":[],"Resource":[]}]`.
diff --git a/packages/amplify-cli/src/commands/gen2-migration/generate.ts b/packages/amplify-cli/src/commands/gen2-migration/generate.ts
@@ -71,6 +71,11 @@ export class AmplifyMigrationGenerateStep extends AmplifyMigrationStep {
     const discovered = this.gen1App.discover();
 
     for (const resource of discovered) {
+      // Skip resources the assessment marked as unsupported for this step.
+      if (assessment.of(resource, 'generate').level !== 'supported') {
+        continue;
+      }
+
       switch (resource.key) {
         case 'auth:Cognito': {
           const isReferenceAuth = discovered
