fix(sns): contentBasedDeduplication is always false for imported topic

packages/@aws-cdk-testing/framework-integ/test/aws-sns/test/integ.sns.js.snapshot/SNSInteg.template.json

@@ -119,6 +119,59 @@
     "SignatureVersion": "2",
     "TopicName": "fooTopicSignatureVersion"
    }
+  },
+  "MyTopic288CE2107": {
+   "Type": "AWS::SNS::Topic",
+   "Properties": {
+    "DisplayName": "fooDisplayName2",
+    "KmsMasterKeyId": {
+     "Fn::GetAtt": [
+      "CustomKey1E6D0D07",
+      "Arn"
+     ]
+    },
+    "TopicName": "fooTopic2"
+   }
+  },
+  "PublishRoleF42F66B6": {
+   "Type": "AWS::IAM::Role",
+   "Properties": {
+    "AssumeRolePolicyDocument": {
+     "Statement": [
+      {
+       "Action": "sts:AssumeRole",
+       "Effect": "Allow",
+       "Principal": {
+        "Service": "s3.amazonaws.com"
+       }
+      }
+     ],
+     "Version": "2012-10-17"
+    }
+   }
+  },
+  "PublishRoleDefaultPolicy9257B12D": {
+   "Type": "AWS::IAM::Policy",
+   "Properties": {
+    "PolicyDocument": {
+     "Statement": [
+      {
+       "Action": "sns:Publish",
+       "Effect": "Allow",
+       "Resource": {
+        "Ref": "MyTopic288CE2107"
+       }
+      }
+     ],
+     "Version": "2012-10-17"
+    },
+    "PolicyName": "PublishRoleDefaultPolicy9257B12D",
+    "Roles": [
+     {
+      "Ref": "PublishRoleF42F66B6"
+     }
+    ]
+   }
   }
  },
  "Parameters": {

packages/@aws-cdk-testing/framework-integ/test/aws-sns/test/integ.sns.ts

@@ -44,11 +44,25 @@ class SNSInteg extends Stack {
       successFeedbackSampleRate: 50,
     });
 
+    // Topic with signatureVersion
     new Topic(this, 'MyTopicSignatureVersion', {
       topicName: 'fooTopicSignatureVersion',
       displayName: 'fooDisplayNameSignatureVersion',
       signatureVersion: '2',
     });
+
+    // Can import topic
+    const topic2 = new Topic(this, 'MyTopic2', {
+      topicName: 'fooTopic2',
+      displayName: 'fooDisplayName2',
+      masterKey: key,
+    });
+    const importedTopic = Topic.fromTopicArn(this, 'ImportedTopic', topic2.topicArn);
+
+    const publishRole = new Role(this, 'PublishRole', {
+      assumedBy: new ServicePrincipal('s3.amazonaws.com'),
+    });
+    importedTopic.grantPublish(publishRole);
   }
 }
 

packages/aws-cdk-lib/aws-sns/lib/topic.ts

@@ -153,6 +153,24 @@ export enum LoggingProtocol {
   APPLICATION = 'application',
 }
 
+/**
+ * Represents an SNS topic defined outside of this stack.
+ */
+export interface TopicAttributes {
+  /**
+   * The ARN of the SNS topic.
+   */
+  readonly topicArn: string;
+
+  /**
+   * Whether content-based deduplication is enabled.
+   * Only applicable for FIFO topics.
+   *
+   * @default false
+   */
+  readonly contentBasedDeduplication?: boolean;
+}
+
 /**
  * A new SNS topic
  */
@@ -166,16 +184,34 @@ export class Topic extends TopicBase {
    * @param topicArn topic ARN (i.e. arn:aws:sns:us-east-2:444455556666:MyTopic)
    */
   public static fromTopicArn(scope: Construct, id: string, topicArn: string): ITopic {
+    return Topic.fromTopicAttributes(scope, id, { topicArn });
+  };
+
+  /**
+   * Import an existing SNS topic provided a topic attributes
+   *
+   * @param scope The parent creating construct
+   * @param id The construct's name
+   * @param attrs the attributes of the topic to import
+   */
+  public static fromTopicAttributes(scope: Construct, id: string, attrs: TopicAttributes): ITopic {
+    const topicName = Stack.of(scope).splitArn(attrs.topicArn, ArnFormat.NO_RESOURCE_NAME).resource;
+    const fifo = topicName.endsWith('.fifo');
+
+    if (attrs.contentBasedDeduplication && !fifo) {
+      throw new Error('Cannot import topic; contentBasedDeduplication is only available for FIFO SNS topics.');
+    }
+
     class Import extends TopicBase {
-      public readonly topicArn = topicArn;
-      public readonly topicName = Stack.of(scope).splitArn(topicArn, ArnFormat.NO_RESOURCE_NAME).resource;
-      public readonly fifo = this.topicName.endsWith('.fifo');
-      public readonly contentBasedDeduplication = false;
+      public readonly topicArn = attrs.topicArn;
+      public readonly topicName = topicName;
+      public readonly fifo = fifo;
+      public readonly contentBasedDeduplication = attrs.contentBasedDeduplication || false;
       protected autoCreatePolicy: boolean = false;
     }
 
     return new Import(scope, id, {
-      environmentFromArn: topicArn,
+      environmentFromArn: attrs.topicArn,
     });
   }
 

packages/aws-cdk-lib/aws-sns/test/sns.test.ts

@@ -455,6 +455,48 @@ describe('Topic', () => {
     expect(imported.fifo).toEqual(true);
   });
 
+  test('fromTopicAttributes contentBasedDeduplication false', () => {
+    // GIVEN
+    const stack = new cdk.Stack();
+
+    // WHEN
+    const imported = sns.Topic.fromTopicAttributes(stack, 'Imported', {
+      topicArn: 'arn:aws:sns:*:123456789012:mytopic',
+    });
+
+    // THEN
+    expect(imported.topicName).toEqual('mytopic');
+    expect(imported.topicArn).toEqual('arn:aws:sns:*:123456789012:mytopic');
+    expect(imported.contentBasedDeduplication).toEqual(false);
+  });
+
+  test('fromTopicAttributes contentBasedDeduplication true', () => {
+    // GIVEN
+    const stack = new cdk.Stack();
+
+    // WHEN
+    const imported = sns.Topic.fromTopicAttributes(stack, 'Imported', {
+      topicArn: 'arn:aws:sns:*:123456789012:mytopic.fifo',
+      contentBasedDeduplication: true,
+    });
+
+    // THEN
+    expect(imported.topicName).toEqual('mytopic.fifo');
+    expect(imported.topicArn).toEqual('arn:aws:sns:*:123456789012:mytopic.fifo');
+    expect(imported.contentBasedDeduplication).toEqual(true);
+  });
+
+  test('fromTopicAttributes throws with contentBasedDeduplication on non-fifo topic', () => {
+    // GIVEN
+    const stack = new cdk.Stack();
+
+    // WHEN
+    expect(() => sns.Topic.fromTopicAttributes(stack, 'Imported', {
+      topicArn: 'arn:aws:sns:*:123456789012:mytopic',
+      contentBasedDeduplication: true,
+    })).toThrow(/Cannot import topic; contentBasedDeduplication is only available for FIFO SNS topics./);
+  });
+
   test('sets account for imported topic env', () => {
     // GIVEN
     const stack = new cdk.Stack();