feat: report feature flag configuration into Cloud Assembly

packages/aws-cdk-lib/core/lib/private/feature-flag-report.ts

@@ -0,0 +1,39 @@
+import { ArtifactType, FeatureFlag } from '@aws-cdk/cloud-assembly-schema';
+import { IConstruct } from 'constructs';
+import { CloudAssemblyBuilder } from '../../../cx-api';
+import * as feats from '../../../cx-api/lib/features';
+import { FlagInfo } from '../../../cx-api/lib/private/flag-modeling';
+
+/**
+ * Creates a FeatureFlag object based on flag information given.
+ */
+function parseFeatureFlagInfo(flagName: string, info: FlagInfo, root: IConstruct): FeatureFlag {
+  const userValue = root.node.tryGetContext(flagName) ?? undefined;
+
+  let parsedFlag: FeatureFlag = {
+    userValue: userValue,
+    recommendedValue: info.recommendedValue,
+    explanation: info.summary,
+  };
+
+  return parsedFlag;
+}
+
+/**
+ * Iterate through all feature flags, retrieve the user's context,
+ * and create a Feature Flag report.
+ */
+export function generateFeatureFlagReport(builder: CloudAssemblyBuilder, root: IConstruct): void {
+  const featureFlags: Record<string, FeatureFlag> = {};
+  for (const [flagName, flagInfo] of Object.entries(feats.FLAGS)) {
+    featureFlags[flagName] = parseFeatureFlagInfo(flagName, flagInfo, root);
+  }
+
+  builder.addArtifact('aws-cdk-lib/feature-flag-report', {
+    type: ArtifactType.FEATURE_FLAG_REPORT,
+    properties: {
+      module: 'aws-cdk-lib',
+      flags: featureFlags,
+    },
+  });
+}

packages/aws-cdk-lib/core/lib/private/synthesis.ts

@@ -15,6 +15,7 @@ import { Stack } from '../stack';
 import { ISynthesisSession } from '../stack-synthesizers/types';
 import { Stage, StageSynthesisOptions } from '../stage';
 import { IPolicyValidationPluginBeta1 } from '../validation';
+import { generateFeatureFlagReport } from './feature-flag-report';
 import { ConstructTree } from '../validation/private/construct-tree';
 import { PolicyValidationReportFormatter, NamedValidationPluginReport } from '../validation/private/report';
 
@@ -64,6 +65,8 @@ export function synthesize(root: IConstruct, options: SynthesisOptions = { }): c
   // stacks to add themselves to the synthesized cloud assembly.
   synthesizeTree(root, builder, options.validateOnSynthesis);
 
+  generateFeatureFlagReport(builder, root);
+
   const assembly = builder.buildAssembly();
 
   invokeValidationPlugins(root, builder.outdir, assembly);

packages/aws-cdk-lib/core/test/feature-flag-report.test.ts

@@ -0,0 +1,51 @@
+import { FeatureFlagReportProperties } from '@aws-cdk/cloud-assembly-schema';
+import * as cxapi from '../../cx-api';
+import { App } from '../lib';
+import { generateFeatureFlagReport } from '../lib/private/feature-flag-report';
+
+describe('generate feature flag report', () => {
+  test('feature flag report can be retrieved from CloudAssembly using its artifact ID', () => {
+    const app = new App();
+    const assembly = app.synth();
+    expect(assembly.manifest.artifacts?.['aws-cdk-lib/feature-flag-report']).toBeDefined();
+  });
+  test('report contains context values that represent the feature flags', () => {
+    const app = new App({
+      context: {
+        '@aws-cdk/aws-ec2:bastionHostUseAmazonLinux2023ByDefault': true,
+        '@aws-cdk/core:aspectStabilization': false,
+      },
+    });
+    const assembly = app.synth();
+    const report = assembly.manifest.artifacts?.['aws-cdk-lib/feature-flag-report'];
+    expect(report).toEqual(expect.objectContaining({
+      type: 'cdk:feature-flag-report',
+      properties: expect.objectContaining({
+        module: 'aws-cdk-lib',
+        flags: expect.objectContaining({
+          '@aws-cdk/aws-ec2:bastionHostUseAmazonLinux2023ByDefault': expect.objectContaining({
+            userValue: true,
+          }),
+          '@aws-cdk/core:aspectStabilization': expect.objectContaining({
+            userValue: false,
+          }),
+        }),
+      }),
+    }));
+  });
+  test('defaults userValue to undefined when not set in context', () => {
+    const app = new App();
+    const builder = new cxapi.CloudAssemblyBuilder('/tmp/test');
+    const spy = jest.spyOn(builder, 'addArtifact');
+
+    generateFeatureFlagReport(builder, app);
+
+    const flags = (spy.mock.calls[0][1].properties as FeatureFlagReportProperties).flags;
+    expect(flags).toEqual(expect.objectContaining({
+      '@aws-cdk/aws-ec2:bastionHostUseAmazonLinux2023ByDefault': expect.objectContaining({
+        userValue: undefined,
+      }),
+    }));
+  });
+});
+

packages/aws-cdk-lib/core/test/stage.test.ts

@@ -252,7 +252,7 @@ describe('stage', () => {
     const rootAssembly = app.synth();
 
     // THEN
-    expect(rootAssembly.manifest.artifacts).toEqual({
+    expect(rootAssembly.manifest.artifacts).toMatchObject({
       'assembly-StageLevel1': {
         type: 'cdk:cloud-assembly',
         properties: {
@@ -263,7 +263,7 @@ describe('stage', () => {
     });
 
     const assemblyLevel1 = rootAssembly.getNestedAssembly('assembly-StageLevel1');
-    expect(assemblyLevel1.manifest.artifacts).toEqual({
+    expect(assemblyLevel1.manifest.artifacts).toMatchObject({
       'assembly-StageLevel1-StageLevel2': {
         type: 'cdk:cloud-assembly',
         properties: {
@@ -274,7 +274,7 @@ describe('stage', () => {
     });
 
     const assemblyLevel2 = assemblyLevel1.getNestedAssembly('assembly-StageLevel1-StageLevel2');
-    expect(assemblyLevel2.manifest.artifacts).toEqual({
+    expect(assemblyLevel2.manifest.artifacts).toMatchObject({
       'assembly-StageLevel1-StageLevel2-StageLevel3': {
         type: 'cdk:cloud-assembly',
         properties: {

packages/aws-cdk-lib/core/test/synthesis.test.ts

@@ -24,7 +24,7 @@ describe('synthesis', () => {
     // THEN
     expect(app.synth()).toEqual(session); // same session if we synth() again
     expect(list(session.directory)).toEqual(['cdk.out', 'manifest.json', 'tree.json']);
-    expect(readJson(session.directory, 'manifest.json').artifacts).toEqual({
+    expect(readJson(session.directory, 'manifest.json').artifacts).toMatchObject({
       Tree: {
         type: 'cdk:tree',
         properties: { file: 'tree.json' },