feat: initial version of an improved CloudFormation template include …

…experience

This change introduces a new package, `@aws-cdk/cloudformation-include`, that improves the experience of working with existing CloudFormation templates in the CDK. It allows including all resources from a template in your CDK application under a given parent scope, and then referencing the included L1 Cfn* objects in your code. Any modifications to the instances will be reflected in the final CFN template. You can also use the L1 objects when defining other resources,
including L2s.

To facilitate translation from CloudFormation templates, which use UperCamelCase property names, to CDK property objects, which use lowerCamelCase names, this change also includes modifications to the code generation for L1 resources to include a new static method, `fromCloudFormation()`, that contains the logic required to instantiate an L1 class from CloudFormation properties taken from a template.

Related to issue #3537

package.json

@@ -52,6 +52,8 @@
       "@aws-cdk/cdk-assets-schema/semver/**",
       "@aws-cdk/core/minimatch",
       "@aws-cdk/core/minimatch/**",
+      "@aws-cdk/cloudformation-include/yaml",
+      "@aws-cdk/cloudformation-include/yaml/**",
       "@aws-cdk/aws-codepipeline-actions/case",
       "@aws-cdk/aws-codepipeline-actions/case/**",
       "@aws-cdk/aws-ecr-assets/minimatch",

packages/@aws-cdk/cloudformation-include/.eslintrc.js

@@ -0,0 +1,2 @@
+const baseConfig = require('../../../tools/cdk-build-tools/config/eslintrc');
+module.exports = baseConfig;

packages/@aws-cdk/cloudformation-include/.gitignore

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+*.js
+tslint.json
+*.js.map
+*.d.ts
+*.generated.ts
+dist
+lib/generated/resources.ts
+*.tgz
+.jsii
+tsconfig.json
+
+.LAST_BUILD
+.nyc_output
+coverage
+nyc.config.js
+.LAST_PACKAGE
+*.snk
+
+!.eslintrc.js
+!build.js
+cfn-types-2-classes.json

packages/@aws-cdk/cloudformation-include/.npmignore

@@ -0,0 +1,21 @@
+# Don't include original .ts files when doing `npm pack`
+*.ts
+!*.d.ts
+coverage
+.nyc_output
+*.tgz
+
+dist
+.LAST_PACKAGE
+.LAST_BUILD
+!*.js
+.eslintrc.js
+
+# Include .jsii
+!.jsii
+
+*.snk
+
+*.tsbuildinfo
+
+tsconfig.json

packages/@aws-cdk/cloudformation-include/LICENSE

@@ -0,0 +1,201 @@
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packages/@aws-cdk/cloudformation-include/NOTICE

@@ -0,0 +1,2 @@
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packages/@aws-cdk/cloudformation-include/README.md

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+# Include CloudFormation templates in the CDK
+
+<!--BEGIN STABILITY BANNER-->
+---
+
+![cdk-constructs: Experimental](https://img.shields.io/badge/cdk--constructs-experimental-important.svg?style=for-the-badge)
+
+> The APIs of higher level constructs in this module are experimental and under active development. They are subject to non-backward compatible changes or removal in any future version. These are not subject to the [Semantic Versioning](https://semver.org/) model and breaking changes will be announced in the release notes. This means that while you may use them, you may need to update your source code when upgrading to a newer version of this package.
+
+---
+<!--END STABILITY BANNER-->
+
+This module contains a set of classes whose goal is to facilitate working
+with existing CloudFormation templates in the CDK.
+It can be thought of as an extension of the capabilities of the
+[`CfnInclude` class](../@aws-cdk/core/lib/cfn-include.ts).
+
+## Basic usage
+
+Assume we have a file `my-template.json`, that contains the following CloudFormation template:
+
+```json
+{
+  "Resources": {
+    "Bucket": {
+      "Type": "AWS::S3::Bucket",
+      "Properties": {
+        "BucketName": "some-bucket-name"
+      }
+    }
+  }
+}
+```
+
+It can be included in a CDK application with the following code:
+
+```typescript
+import * as cfn_inc from '@aws-cdk/cloudformation-include';
+
+const cfnTemplate = new cfn_inc.CfnInclude(this, 'Template', {
+  templateFile: 'my-template.json',
+});
+```
+
+This will add all resources from `my-template.json` into the CDK application,
+preserving their original logical IDs from the template file.
+
+Any resource from the included template can be retrieved by referring to it by its logical ID from the template.
+If you know the class of the CDK object that corresponds to that resource,
+you can cast the returned object to the correct type:
+
+```typescript
+import * as s3 from '@aws-cdk/aws-s3';
+
+const cfnBucket = cfnTemplate.getResource('Bucket') as s3.CfnBucket;
+// cfnBucket is of type s3.CfnBucket
+```
+
+Any modifications made to that resource will be reflected in the resulting CDK template;
+for example, the name of the bucket can be changed:
+
+```typescript
+cfnBucket.bucketName = 'my-bucket-name';
+```
+
+You can also refer to the resource when defining other constructs,
+including the higher-level ones
+(those whose name does not start with `Cfn`),
+for example:
+
+```typescript
+import * as iam from '@aws-cdk/aws-iam';
+
+const role = new iam.Role(this, 'Role', {
+  assumedBy: new iam.AnyPrincipal(),
+});
+role.addToPolicy(new iam.PolicyStatement({
+  actions: ['s3:*'],
+  resources: [cfnBucket.attrArn],
+}));
+```
+
+If you need, you can also convert the CloudFormation resource to a higher-level
+resource by importing it by its name:
+
+```typescript
+const bucket = s3.Bucket.fromBucketName(this, 'L2Bucket', cfnBucket.ref);
+// bucket is of type s3.IBucket
+```
+
+## Known limitations
+
+This module is still in its early, experimental stage,
+and so does not implement all features of CloudFormation templates.
+All items unchecked below are currently not supported.
+
+### Ability to retrieve CloudFormation objects from the template:
+
+- [x] Resources
+- [ ] Parameters
+- [ ] Conditions
+- [ ] Outputs
+
+### [Resource attributes](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-product-attribute-reference.html):
+
+- [x] Properties
+- [ ] Condition
+- [ ] DependsOn
+- [ ] CreationPolicy
+- [ ] UpdatePolicy
+- [x] UpdateReplacePolicy
+- [x] DeletionPolicy
+- [x] Metadata
+
+### [CloudFormation functions](https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/intrinsic-function-reference.html):
+
+- [x] Ref
+- [x] Fn::GetAtt
+- [x] Fn::Join
+- [x] Fn::If
+- [ ] Fn::And
+- [ ] Fn::Equals
+- [ ] Fn::Not
+- [ ] Fn::Or
+- [ ] Fn::Base64
+- [ ] Fn::Cidr
+- [ ] Fn::FindInMap
+- [ ] Fn::GetAZs
+- [ ] Fn::ImportValue
+- [ ] Fn::Select
+- [ ] Fn::Split
+- [ ] Fn::Sub
+- [ ] Fn::Transform