fix(allow ITable for dynamodb stream patterns)

Author: hnishar

source/patterns/@aws-solutions-constructs/aws-dynamodb-stream-lambda-elasticsearch-kibana/lib/index.ts

@@ -51,7 +51,7 @@ export interface DynamoDBStreamToLambdaToElasticSearchAndKibanaProps {
    *
    * @default - None
    */
-  readonly existingTableObj?: dynamodb.Table,
+  readonly existingTableObj?: dynamodb.ITable,
   /**
    * Optional user provided props to override the default props
    *
@@ -101,7 +101,7 @@ export class DynamoDBStreamToLambdaToElasticSearchAndKibana extends Construct {
   private dynamoDBStreamToLambda: DynamoDBStreamToLambda;
   private lambdaToElasticSearchAndKibana: LambdaToElasticSearchAndKibana;
   public readonly lambdaFunction: lambda.Function;
-  public readonly dynamoTable: dynamodb.Table;
+  public readonly dynamoTable?: dynamodb.Table;
   public readonly userPool: cognito.UserPool;
   public readonly userPoolClient: cognito.UserPoolClient;
   public readonly identityPool: cognito.CfnIdentityPool;

source/patterns/@aws-solutions-constructs/aws-dynamodb-stream-lambda/lib/index.ts

@@ -45,7 +45,7 @@ export interface DynamoDBStreamToLambdaProps {
    *
    * @default - None
    */
-  readonly existingTableObj?: dynamodb.Table,
+  readonly existingTableObj?: dynamodb.ITable,
   /**
    * Optional user provided props to override the default props
    *
@@ -69,7 +69,7 @@ export interface DynamoDBStreamToLambdaProps {
 
 export class DynamoDBStreamToLambda extends Construct {
   public readonly lambdaFunction: lambda.Function;
-  public readonly dynamoTable: dynamodb.Table;
+  public readonly dynamoTable?: dynamodb.Table;
 
   /**
    * @summary Constructs a new instance of the LambdaToDynamoDB class.
@@ -88,20 +88,24 @@ export class DynamoDBStreamToLambda extends Construct {
       lambdaFunctionProps: props.lambdaFunctionProps
     });
 
-    this.dynamoTable = defaults.buildDynamoDBTableWithStream(this, {
+    const table: dynamodb.ITable = defaults.buildDynamoDBTableWithStream(this, {
       dynamoTableProps: props.dynamoTableProps,
       existingTableObj: props.existingTableObj
     });
 
+    if (table instanceof dynamodb.Table) {
+      this.dynamoTable = table;
+    }
+
     // Grant DynamoDB Stream read perimssion for lambda function
-    this.dynamoTable.grantStreamRead(this.lambdaFunction.grantPrincipal);
+    table.grantStreamRead(this.lambdaFunction.grantPrincipal);
 
     // Add the Lambda event source mapping
     const eventSourceProps = defaults.DynamoEventSourceProps(this, {
       eventSourceProps: props.dynamoEventSourceProps,
       deploySqsDlqQueue: props.deploySqsDlqQueue,
       sqsDlqQueueProps: props.sqsDlqQueueProps
     });
-    this.lambdaFunction.addEventSource(new DynamoEventSource(this.dynamoTable, eventSourceProps));
+    this.lambdaFunction.addEventSource(new DynamoEventSource(table, eventSourceProps));
   }
 }

source/patterns/@aws-solutions-constructs/aws-dynamodb-stream-lambda/test/dynamodb-stream-lambda.test.ts

@@ -205,4 +205,70 @@ test('check exception for Missing existingObj from props', () => {
   } catch (e) {
     expect(e).toBeInstanceOf(Error);
   }
+});
+
+test('check dynamodb table stream override with ITable', () => {
+  const stack = new cdk.Stack();
+  const existingTableObj = dynamodb.Table.fromTableAttributes(stack, 'existingtable', {
+    tableArn: 'arn:aws:dynamodb:us-east-1:xxxxxxxxxxxxx:table/existing-table',
+    tableStreamArn: 'arn:aws:dynamodb:us-east-1:xxxxxxxxxxxxx:table/existing-table/stream/2020-06-22T18:34:05.824'
+  });
+  const props: DynamoDBStreamToLambdaProps = {
+    lambdaFunctionProps: {
+      code: lambda.Code.fromAsset(`${__dirname}/lambda`),
+      runtime: lambda.Runtime.NODEJS_12_X,
+      handler: 'index.handler'
+    },
+    existingTableObj
+  };
+
+  new DynamoDBStreamToLambda(stack, 'test-lambda-dynamodb-stack', props);
+
+  expect(stack).toHaveResource('AWS::Lambda::EventSourceMapping', {
+    EventSourceArn: "arn:aws:dynamodb:us-east-1:xxxxxxxxxxxxx:table/existing-table/stream/2020-06-22T18:34:05.824",
+  });
+
+  expect(stack).toHaveResource('AWS::IAM::Policy', {
+    PolicyDocument: {
+      Statement: [
+        {
+          Action: [
+            "xray:PutTraceSegments",
+            "xray:PutTelemetryRecords"
+          ],
+          Effect: "Allow",
+          Resource: "*"
+        },
+        {
+          Action: "dynamodb:ListStreams",
+          Effect: "Allow",
+          Resource: "*"
+        },
+        {
+          Action: [
+            "dynamodb:DescribeStream",
+            "dynamodb:GetRecords",
+            "dynamodb:GetShardIterator"
+          ],
+          Effect: "Allow",
+          Resource: "arn:aws:dynamodb:us-east-1:xxxxxxxxxxxxx:table/existing-table/stream/2020-06-22T18:34:05.824"
+        },
+        {
+          Action: [
+            "sqs:SendMessage",
+            "sqs:GetQueueAttributes",
+            "sqs:GetQueueUrl"
+          ],
+          Effect: "Allow",
+          Resource: {
+            "Fn::GetAtt": [
+              "testlambdadynamodbstackSqsDlqQueue4CC9868B",
+              "Arn"
+            ]
+          }
+        }
+      ],
+      Version: "2012-10-17"
+    }
+  });
 });

source/patterns/@aws-solutions-constructs/core/lib/dynamodb-table-helper.ts

@@ -32,6 +32,22 @@ export interface BuildDynamoDBTableProps {
   readonly existingTableObj?: dynamodb.Table
 }
 
+export interface BuildDynamoDBTableWithStreamProps {
+  /**
+   * Optional user provided props to override the default props
+   *
+   * @default - Default props are used
+   */
+  readonly dynamoTableProps?: dynamodb.TableProps,
+  /**
+   * Existing instance of dynamodb table object.
+   * Providing both this and `dynamoTableProps` will cause an error.
+   *
+   * @default - None
+   */
+  readonly existingTableObj?: dynamodb.ITable
+}
+
 export function buildDynamoDBTable(scope: cdk.Construct, props: BuildDynamoDBTableProps): dynamodb.Table {
   // Conditional DynamoDB Table creation
   if (!props.existingTableObj) {
@@ -47,7 +63,7 @@ export function buildDynamoDBTable(scope: cdk.Construct, props: BuildDynamoDBTab
   }
 }
 
-export function buildDynamoDBTableWithStream(scope: cdk.Construct, props: BuildDynamoDBTableProps): dynamodb.Table {
+export function buildDynamoDBTableWithStream(scope: cdk.Construct, props: BuildDynamoDBTableWithStreamProps): dynamodb.ITable {
   // Conditional DynamoDB Table creation
   if (!props.existingTableObj) {
     // Set the default props for DynamoDB table