feat(core): add applyRemovalPolicy to IResource (aws#17746)

The motivation behind this change is in both the linked issue and the added test case: change removal policy of a child resource with an interface type.

Thanks @skinny85 for pointing me in the right direction.

Closes aws#17728

----

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

packages/@aws-cdk/aws-ec2/test/client-vpn-authorization-rule.test.ts

@@ -23,6 +23,7 @@ describe('ClientVpnAuthorizationRule constructor', () => {
       env: { account: 'myAccount', region: 'us-east-1' },
       connections: new Connections(),
       node: stack.node,
+      applyRemovalPolicy: () => { },
     };
     new ClientVpnAuthorizationRule(stack, 'NormalRule', {
       cidr: '10.0.10.0/32',
@@ -50,6 +51,7 @@ describe('ClientVpnAuthorizationRule constructor', () => {
       env: { account: 'myAccount', region: 'us-east-1' },
       connections: new Connections(),
       node: stack.node,
+      applyRemovalPolicy: () => { },
     };
     const clientVpnEndpoint: IClientVpnEndpoint = {
       endpointId: 'myClientVpnEndpoint',
@@ -58,6 +60,7 @@ describe('ClientVpnAuthorizationRule constructor', () => {
       env: { account: 'myAccount', region: 'us-east-1' },
       connections: new Connections(),
       node: stack.node,
+      applyRemovalPolicy: () => { },
     };
     expect(() => {
       new ClientVpnAuthorizationRule(stack, 'RuleBothEndointAndEndpoint', {
@@ -88,6 +91,7 @@ describe('ClientVpnAuthorizationRule constructor', () => {
       env: { account: 'myAccount', region: 'us-east-1' },
       connections: new Connections(),
       node: stack.node,
+      applyRemovalPolicy: () => { },
     };
     new ClientVpnAuthorizationRule(stack, 'RuleWithEndointTypo', {
       cidr: '10.0.10.0/32',

packages/@aws-cdk/aws-lambda/lib/function-base.ts

@@ -334,6 +334,7 @@ export abstract class FunctionBase extends Resource implements IFunction, ec2.IC
           node: this.node,
           stack: this.stack,
           env: this.env,
+          applyRemovalPolicy: this.applyRemovalPolicy,
         },
       });
       this._invocationGrants[identifier] = grant;

packages/@aws-cdk/core/lib/resource.ts

@@ -58,6 +58,19 @@ export interface IResource extends IConstruct {
    * that might be different than the stack they were imported into.
    */
   readonly env: ResourceEnvironment;
+
+  /**
+   * Apply the given removal policy to this resource
+   *
+   * The Removal Policy controls what happens to this resource when it stops
+   * being managed by CloudFormation, either because you've removed it from the
+   * CDK application or because you've made a change that requires the resource
+   * to be replaced.
+   *
+   * The resource can be deleted (`RemovalPolicy.DESTROY`), or left in your AWS
+   * account for data recovery and cleanup later (`RemovalPolicy.RETAIN`).
+   */
+  applyRemovalPolicy(policy: RemovalPolicy): void;
 }
 
 /**

packages/@aws-cdk/core/test/resource.test.ts

@@ -2,7 +2,7 @@ import * as cxapi from '@aws-cdk/cx-api';
 import {
   App, App as Root, CfnCondition,
   CfnDeletionPolicy, CfnResource, Construct,
-  Fn, RemovalPolicy, Resource, Stack,
+  Fn, IResource, RemovalPolicy, Resource, Stack,
 } from '../lib';
 import { synthesize } from '../lib/private/synthesis';
 import { toCloudFormation } from './util';
@@ -318,6 +318,33 @@ describe('resource', () => {
 
   });
 
+  test('applyRemovalPolicy available for interface resources', () => {
+    class Child extends Resource {
+      constructor(scope: Construct, id: string) {
+        super(scope, id);
+
+        new CfnResource(this, 'Resource', {
+          type: 'ChildResourceType',
+        });
+      }
+    }
+
+    const stack = new Stack();
+    const child: IResource = new Child(stack, 'Child');
+
+    child.applyRemovalPolicy(RemovalPolicy.RETAIN);
+
+    expect(toCloudFormation(stack)).toEqual({
+      Resources: {
+        ChildDAB30558: {
+          DeletionPolicy: 'Retain',
+          Type: 'ChildResourceType',
+          UpdateReplacePolicy: 'Retain',
+        },
+      },
+    });
+  });
+
   test('addDependency adds all dependencyElements of dependent constructs', () => {
 
     class C1 extends Construct {