How to Properly Invoke AWS Lambda from DynamoDB Streams Using Node.js

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When working with AWS, you may find yourself needing to invoke a Lambda function in response to changes made in DynamoDB. Specifically, many developers want to execute specific code only when a new record is added to their DynamoDB table. However, doing this correctly can be a bit tricky, as evidenced by the common challenges faced by developers trying to set this up. Today, we’ll walk through how to set up an AWS Lambda function to be invoked from DynamoDB Streams, outlining both the configuration and the necessary code behind it.

Problem Statement

In your scenario, you’re looking to trigger a Lambda function based on insert events from a DynamoDB table. The initial attempt at this was made using code executed through the AWS console, which worked fine. However, the real challenge arose when ensuring that the Lambda function would also run successfully when a new record is added to the database. Your current implementation did not produce the desired results, leaving you looking for guidance.

Solution Overview

To properly invoke your Lambda function from a DynamoDB Stream, you will need to configure the respective Lambda function to listen for events from the DynamoDB Streams service. Let’s break down the solution into clear steps:

Step 1: Configuring DynamoDB Stream Events

[[See Video to Reveal this Text or Code Snippet]]

batchSize: How many records to process in a single batch.

batchWindow: Time in seconds before processing batching events.

bisectBatchOnFunctionError: Splits failed batches for troubleshooting.

maximumRetryAttempts: How many times to retry on errors.

maximumRecordAgeInSeconds: Maximum age of a record before it's ignored.

Step 2: Implementing the Lambda Function Logic

Use the following code snippet to set up the main Lambda function that handles DynamoDB Stream events:

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Create the Invoke Lambda Function

This function handles the actual invocation of your Lambda function when the conditions in the previous step are met:

[[See Video to Reveal this Text or Code Snippet]]

Notes on Configuration

Ensure your Lambda function has the necessary permissions to be triggered by DynamoDB Streams. This can often be set up within the IAM role associated with your Lambda function.

Make sure to adjust the FunctionName in the invoke parameters to match the intended function you wish to call.

Conclusion

Connecting AWS Lambda to DynamoDB Streams allows for a seamless integration that automates responses to database changes in real-time. With the configuration set as specified and the Lambda function coded correctly, you’ll be able to efficiently handle new records added to your DynamoDB table. By following these guidelines, you can eliminate the complexities that often come with invoking Lambda functions in AWS. Enjoy building your applications with this newfound knowledge!