feat: ignore metadata

README.md

@@ -177,6 +177,27 @@ test('propertyMatchers', () => {
 });
 ```
 
+## Ignore Metadata
+
+With this enabled CloudFormation metadata both on Stack and Resource level will be ignored.
+Metadata is often added by Aspects or other libraries.
+
+```typescript
+import { Stack } from 'aws-cdk-lib/core';
+import { Bucket } from 'aws-cdk-lib/aws-s3';
+import 'jest-cdk-snapshot';
+
+test('default setup', () => {
+  const stack = new Stack();
+
+  new Bucket(stack, 'Foo');
+
+  expect(stack).toMatchCdkSnapshot({
+    ignoreMetadata: true,
+  });
+});
+```
+
 ## License
 
 [MIT](LICENSE)

src/__tests__/__snapshots__/index.test.ts.snap

@@ -205,6 +205,18 @@ exports[`ignore current version 1`] = `
 }
 `;
 
+exports[`metadata should not be included if skipped 1`] = `
+{
+  "Resources": {
+    "FooDFE0DD70": {
+      "DeletionPolicy": "Retain",
+      "Type": "AWS::S3::Bucket",
+      "UpdateReplacePolicy": "Retain",
+    },
+  },
+}
+`;
+
 exports[`multiple resources 1`] = `
 {
   "Resources": {

src/__tests__/index.test.ts

@@ -1,4 +1,11 @@
-import { CfnOutput, CfnParameter, Stack } from "aws-cdk-lib";
+import {
+  Aspects,
+  CfnOutput,
+  CfnParameter,
+  CfnResource,
+  IAspect,
+  Stack,
+} from "aws-cdk-lib";
 import { Code, Function, Runtime } from "aws-cdk-lib/aws-lambda";
 import { AccountPrincipal } from "aws-cdk-lib/aws-iam";
 import { Bucket } from "aws-cdk-lib/aws-s3";
@@ -143,3 +150,34 @@ test("show bootstrap version if ignoreBootstrapVersion is explicitly false", ()
     ignoreBootstrapVersion: false,
   });
 });
+
+test("metadata should not be included if skipped", () => {
+  const stack = new Stack();
+  // There is different methods and places where metadata can be added. We want to ensure none leave a trace
+  // adding metadata via Aspect and cfnOptions
+  const dataAdder: IAspect = {
+    visit: (node) => {
+      if (CfnResource.isCfnResource(node)) {
+        node.cfnOptions.metadata = {
+          ...node.cfnOptions.metadata,
+          ["dummyKey"]: "dummyValue",
+        };
+      }
+    },
+  };
+  Aspects.of(stack).add(dataAdder);
+
+  // Add metadata on Stack level
+  stack.addMetadata("stackMeta", "dummy");
+
+  // Add metadata on different resource levels
+  const bucket = new Bucket(stack, "Foo");
+  bucket.node.addMetadata("nodeMetadata", "dummy");
+  if (bucket.node.defaultChild) {
+    bucket.node.defaultChild.node.addMetadata("resourceMetadata", "dummy");
+  }
+
+  expect(stack).toMatchCdkSnapshot({
+    ignoreMetadata: true,
+  });
+});

src/index.ts

@@ -60,6 +60,11 @@ export type Options = StageSynthesisOptions & {
    * Defaults to `true`.
    */
   ignoreBootstrapVersion?: boolean;
+
+  /**
+   * Ignore Metadata
+   */
+  ignoreMetadata?: boolean;
 };
 
 const currentVersionRegex = /^(.+CurrentVersion[0-9A-F]{8})[0-9a-f]{32}$/;
@@ -121,6 +126,7 @@ const convertStack = (stack: Stack, options: Options = {}) => {
     ignoreAssets = false,
     ignoreBootstrapVersion = true,
     ignoreCurrentVersion = false,
+    ignoreMetadata = false,
     subsetResourceTypes,
     subsetResourceKeys,
     ...synthOptions
@@ -184,6 +190,19 @@ const convertStack = (stack: Stack, options: Options = {}) => {
     }
   }
 
+  if (ignoreMetadata && template.Metadata) {
+    delete template.Metadata;
+  }
+
+  if (ignoreMetadata && template.Resources) {
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    Object.values(template.Resources).forEach((resource: any) => {
+      if (resource?.Metadata) {
+        delete resource.Metadata;
+      }
+    });
+  }
+
   return yaml ? jsYaml.safeDump(template) : template;
 };