fix(diff): handle YAML short-forms like '!GetAtt' in diff (aws#10381)

CloudFormation allows using short-form versions of intrinsic functions like `!GetAtt`.
We handled them correctly in the `@aws-cdk/cloudformation-include` module,
so extract that logic to a common package,
and use it from the CLI in the `diff` command as well.

Fixes aws#6537

----

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

package.json

@@ -61,14 +61,14 @@
       "@aws-cdk/cloud-assembly-schema/jsonschema/**",
       "@aws-cdk/cloud-assembly-schema/semver",
       "@aws-cdk/cloud-assembly-schema/semver/**",
-      "@aws-cdk/cloudformation-include/yaml",
-      "@aws-cdk/cloudformation-include/yaml/**",
       "@aws-cdk/core/fs-extra",
       "@aws-cdk/core/fs-extra/**",
       "@aws-cdk/core/minimatch",
       "@aws-cdk/core/minimatch/**",
       "@aws-cdk/cx-api/semver",
       "@aws-cdk/cx-api/semver/**",
+      "@aws-cdk/yaml-cfn/yaml",
+      "@aws-cdk/yaml-cfn/yaml/**",
       "aws-cdk-lib/case",
       "aws-cdk-lib/case/**",
       "aws-cdk-lib/fs-extra",

packages/@aws-cdk/cloudformation-include/lib/file-utils.ts

@@ -1,7 +1,5 @@
 import * as fs from 'fs';
-import * as yaml from 'yaml';
-import * as yaml_cst from 'yaml/parse-cst';
-import * as yaml_types from 'yaml/types';
+import * as yaml_cfn from '@aws-cdk/yaml-cfn';
 
 export function readJsonSync(filePath: string): any {
   const fileContents = fs.readFileSync(filePath);
@@ -10,62 +8,5 @@ export function readJsonSync(filePath: string): any {
 
 export function readYamlSync(filePath: string): any {
   const fileContents = fs.readFileSync(filePath);
-  return parseYamlStrWithCfnTags(fileContents.toString());
-}
-
-function makeTagForCfnIntrinsic(
-  intrinsicName: string, addFnPrefix: boolean = true,
-  resolveFun?: (_doc: yaml.Document, cstNode: yaml_cst.CST.Node) => any): yaml_types.Schema.CustomTag {
-
-  return {
-    identify(value: any) { return typeof value === 'string'; },
-    tag: `!${intrinsicName}`,
-    resolve: resolveFun || ((_doc: yaml.Document, cstNode: yaml_cst.CST.Node) => {
-      const ret: any = {};
-      ret[addFnPrefix ? `Fn::${intrinsicName}` : intrinsicName] =
-        // the +1 is to account for the ! the short form begins with
-        parseYamlStrWithCfnTags(cstNode.toString().substring(intrinsicName.length + 1));
-      return ret;
-    }),
-  };
-}
-
-const shortForms: yaml_types.Schema.CustomTag[] = [
-  'Base64', 'Cidr', 'FindInMap', 'GetAZs', 'ImportValue', 'Join', 'Sub',
-  'Select', 'Split', 'Transform', 'And', 'Equals', 'If', 'Not', 'Or',
-].map(name => makeTagForCfnIntrinsic(name)).concat(
-  makeTagForCfnIntrinsic('Ref', false),
-  makeTagForCfnIntrinsic('Condition', false),
-  makeTagForCfnIntrinsic('GetAtt', true, (_doc: yaml.Document, cstNode: yaml_cst.CST.Node): any => {
-    const parsedArguments = parseYamlStrWithCfnTags(cstNode.toString().substring('!GetAtt'.length));
-
-    let value: any;
-    if (typeof parsedArguments === 'string') {
-      // if the arguments to !GetAtt are a string,
-      // the part before the first '.' is the logical ID,
-      // and the rest is the attribute name
-      // (which can contain '.')
-      const firstDot = parsedArguments.indexOf('.');
-      if (firstDot === -1) {
-        throw new Error(`Short-form Fn::GetAtt must contain a '.' in its string argument, got: '${parsedArguments}'`);
-      }
-      value = [
-        parsedArguments.substring(0, firstDot),
-        parsedArguments.substring(firstDot + 1), // the + 1 is to skip the actual '.'
-      ];
-    } else {
-      // this is the form where the arguments to Fn::GetAtt are already an array -
-      // in this case, nothing more to do
-      value = parsedArguments;
-    }
-
-    return { 'Fn::GetAtt': value };
-  }),
-);
-
-function parseYamlStrWithCfnTags(text: string): any {
-  return yaml.parse(text, {
-    customTags: shortForms,
-    schema: 'yaml-1.1',
-  });
+  return yaml_cfn.deserialize(fileContents.toString());
 }

packages/@aws-cdk/cloudformation-include/package.json

@@ -68,6 +68,7 @@
     "@aws-cdk/aws-apigatewayv2": "0.0.0",
     "@aws-cdk/aws-appconfig": "0.0.0",
     "@aws-cdk/aws-applicationautoscaling": "0.0.0",
+    "@aws-cdk/aws-applicationinsights": "0.0.0",
     "@aws-cdk/aws-appmesh": "0.0.0",
     "@aws-cdk/aws-appstream": "0.0.0",
     "@aws-cdk/aws-appsync": "0.0.0",
@@ -89,6 +90,7 @@
     "@aws-cdk/aws-codecommit": "0.0.0",
     "@aws-cdk/aws-codedeploy": "0.0.0",
     "@aws-cdk/aws-codeguruprofiler": "0.0.0",
+    "@aws-cdk/aws-codegurureviewer": "0.0.0",
     "@aws-cdk/aws-codepipeline": "0.0.0",
     "@aws-cdk/aws-codestar": "0.0.0",
     "@aws-cdk/aws-codestarconnections": "0.0.0",
@@ -180,9 +182,7 @@
     "@aws-cdk/aws-wafv2": "0.0.0",
     "@aws-cdk/aws-workspaces": "0.0.0",
     "@aws-cdk/core": "0.0.0",
-    "yaml": "1.10.0",
-    "@aws-cdk/aws-applicationinsights": "0.0.0",
-    "@aws-cdk/aws-codegurureviewer": "0.0.0"
+    "@aws-cdk/yaml-cfn": "0.0.0"
   },
   "peerDependencies": {
     "@aws-cdk/alexa-ask": "0.0.0",
@@ -194,6 +194,7 @@
     "@aws-cdk/aws-apigatewayv2": "0.0.0",
     "@aws-cdk/aws-appconfig": "0.0.0",
     "@aws-cdk/aws-applicationautoscaling": "0.0.0",
+    "@aws-cdk/aws-applicationinsights": "0.0.0",
     "@aws-cdk/aws-appmesh": "0.0.0",
     "@aws-cdk/aws-appstream": "0.0.0",
     "@aws-cdk/aws-appsync": "0.0.0",
@@ -215,6 +216,7 @@
     "@aws-cdk/aws-codecommit": "0.0.0",
     "@aws-cdk/aws-codedeploy": "0.0.0",
     "@aws-cdk/aws-codeguruprofiler": "0.0.0",
+    "@aws-cdk/aws-codegurureviewer": "0.0.0",
     "@aws-cdk/aws-codepipeline": "0.0.0",
     "@aws-cdk/aws-codestar": "0.0.0",
     "@aws-cdk/aws-codestarconnections": "0.0.0",
@@ -257,6 +259,7 @@
     "@aws-cdk/aws-iotanalytics": "0.0.0",
     "@aws-cdk/aws-iotevents": "0.0.0",
     "@aws-cdk/aws-iotthingsgraph": "0.0.0",
+    "@aws-cdk/aws-kendra": "0.0.0",
     "@aws-cdk/aws-kinesis": "0.0.0",
     "@aws-cdk/aws-kinesisanalytics": "0.0.0",
     "@aws-cdk/aws-kinesisfirehose": "0.0.0",
@@ -296,6 +299,7 @@
     "@aws-cdk/aws-sns": "0.0.0",
     "@aws-cdk/aws-sqs": "0.0.0",
     "@aws-cdk/aws-ssm": "0.0.0",
+    "@aws-cdk/aws-sso": "0.0.0",
     "@aws-cdk/aws-stepfunctions": "0.0.0",
     "@aws-cdk/aws-synthetics": "0.0.0",
     "@aws-cdk/aws-transfer": "0.0.0",
@@ -304,25 +308,18 @@
     "@aws-cdk/aws-wafv2": "0.0.0",
     "@aws-cdk/aws-workspaces": "0.0.0",
     "@aws-cdk/core": "0.0.0",
-    "constructs": "^3.0.4",
-    "@aws-cdk/aws-applicationinsights": "0.0.0",
-    "@aws-cdk/aws-codegurureviewer": "0.0.0",
-    "@aws-cdk/aws-kendra": "0.0.0",
-    "@aws-cdk/aws-sso": "0.0.0"
+    "@aws-cdk/yaml-cfn": "0.0.0",
+    "constructs": "^3.0.4"
   },
   "devDependencies": {
     "@aws-cdk/assert": "0.0.0",
     "@types/jest": "^26.0.14",
-    "@types/yaml": "1.9.6",
     "cdk-build-tools": "0.0.0",
     "cdk-integ-tools": "0.0.0",
     "jest": "^26.4.2",
     "pkglint": "0.0.0",
     "ts-jest": "^26.3.0"
   },
-  "bundledDependencies": [
-    "yaml"
-  ],
   "keywords": [
     "aws",
     "cdk",

packages/@aws-cdk/yaml-cfn/.eslintrc.js

@@ -0,0 +1,3 @@
+const baseConfig = require('cdk-build-tools/config/eslintrc');
+baseConfig.parserOptions.project = __dirname + '/tsconfig.json';
+module.exports = baseConfig;

packages/@aws-cdk/yaml-cfn/.gitignore

@@ -0,0 +1,18 @@
+*.js
+*.js.map
+*.d.ts
+node_modules
+dist
+tsconfig.json
+.jsii
+
+.LAST_BUILD
+.LAST_PACKAGE
+*.snk
+.nyc_output
+coverage
+nyc.config.js
+!.eslintrc.js
+!jest.config.js
+
+junit.xml

packages/@aws-cdk/yaml-cfn/.npmignore

@@ -0,0 +1,26 @@
+# Don't include original .ts files when doing `npm pack`
+*.ts
+!*.d.ts
+coverage
+.nyc_output
+*.tgz
+
+dist
+.LAST_PACKAGE
+.LAST_BUILD
+!*.js
+
+# Include .jsii
+!.jsii
+
+*.snk
+
+*.tsbuildinfo
+
+tsconfig.json
+.eslintrc.js
+jest.config.js
+
+# exclude cdk artifacts
+**/cdk.out
+junit.xml