fix(secretsmanager): automatic rotation cannot be disabled (#18906)

fixes #18749

Adds a `manualRotation` prop to `RotationSchedule` in order to leave `automaticallyAfterDays` unset on the underlying Cfn resource.

----

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

Author: AdamVD

Diff for: packages/@aws-cdk/aws-secretsmanager/lib/rotation-schedule.ts

@@ -29,6 +29,8 @@ export interface RotationScheduleOptions {
    * Specifies the number of days after the previous rotation before
    * Secrets Manager triggers the next automatic rotation.
    *
+   * A value of zero will disable automatic rotation - `Duration.days(0)`.
+   *
    * @default Duration.days(30)
    */
   readonly automaticallyAfter?: Duration;
@@ -105,13 +107,23 @@ export class RotationSchedule extends Resource {
       );
     }
 
+    let automaticallyAfterDays: number | undefined = undefined;
+    if (props.automaticallyAfter?.toMilliseconds() !== 0) {
+      automaticallyAfterDays = props.automaticallyAfter?.toDays() || 30;
+    }
+
+    let rotationRules: CfnRotationSchedule.RotationRulesProperty | undefined = undefined;
+    if (automaticallyAfterDays !== undefined) {
+      rotationRules = {
+        automaticallyAfterDays,
+      };
+    }
+
     new CfnRotationSchedule(this, 'Resource', {
       secretId: props.secret.secretArn,
       rotationLambdaArn: props.rotationLambda?.functionArn,
       hostedRotationLambda: props.hostedRotation?.bind(props.secret, this),
-      rotationRules: {
-        automaticallyAfterDays: props.automaticallyAfter && props.automaticallyAfter.toDays() || 30,
-      },
+      rotationRules,
     });
 
     // Prevent secrets deletions when rotation is in place

Diff for: packages/@aws-cdk/aws-secretsmanager/test/rotation-schedule.test.ts

@@ -3,6 +3,7 @@ import * as ec2 from '@aws-cdk/aws-ec2';
 import * as kms from '@aws-cdk/aws-kms';
 import * as lambda from '@aws-cdk/aws-lambda';
 import * as cdk from '@aws-cdk/core';
+import { Duration } from '@aws-cdk/core';
 import * as secretsmanager from '../lib';
 
 let stack: cdk.Stack;
@@ -514,3 +515,42 @@ describe('hosted rotation', () => {
       .toThrow(/Cannot use connections for a hosted rotation that is not deployed in a VPC/);
   });
 });
+
+describe('manual rotations', () => {
+  test('automaticallyAfter with any duration of zero leaves RotationRules unset', () => {
+    const checkRotationNotSet = (automaticallyAfter: Duration) => {
+      // GIVEN
+      const localStack = new cdk.Stack();
+      const secret = new secretsmanager.Secret(localStack, 'Secret');
+      const rotationLambda = new lambda.Function(localStack, 'Lambda', {
+        runtime: lambda.Runtime.NODEJS_10_X,
+        code: lambda.Code.fromInline('export.handler = event => event;'),
+        handler: 'index.handler',
+      });
+
+      // WHEN
+      new secretsmanager.RotationSchedule(localStack, 'RotationSchedule', {
+        secret,
+        rotationLambda,
+        automaticallyAfter,
+      });
+
+      // THEN
+      Template.fromStack(localStack).hasResourceProperties('AWS::SecretsManager::RotationSchedule', Match.objectEquals({
+        SecretId: { Ref: 'SecretA720EF05' },
+        RotationLambdaARN: {
+          'Fn::GetAtt': [
+            'LambdaD247545B',
+            'Arn',
+          ],
+        },
+      }));
+    };
+
+    checkRotationNotSet(Duration.days(0));
+    checkRotationNotSet(Duration.hours(0));
+    checkRotationNotSet(Duration.minutes(0));
+    checkRotationNotSet(Duration.seconds(0));
+    checkRotationNotSet(Duration.millis(0));
+  });
+});