AWS Lambda Enables Cross-Account Access for DynamoDB Streams

/ Tutorial

Posted on: Jan 15, 2026

AWS Lambda has made a significant leap by introducing cross-account access for AWS DynamoDB Streams, empowering developers and organizations to build more efficient event-driven applications. This enhancement allows Lambda functions in one AWS account to trigger from DynamoDB Streams located in another account—eliminating the need for complex data replication strategies and operational overhead. This guide will delve deeply into this innovative feature, providing a detailed overview, technical insights, and actionable steps for implementation.

Table of Contents

  1. Introduction
  2. Understanding AWS Lambda and DynamoDB
  3. 2.1 What is Amazon DynamoDB?
  4. 2.2 What is AWS Lambda?
  5. The Significance of Cross-Account Access
  6. How Cross-Account Access Works
  7. 4.1 Setting Resource-Based Policies
  8. 4.2 Creating an Event-Source Mapping
  9. Use Cases for Cross-Account Access
  10. Implementing Cross-Account Access: Step-by-Step
  11. 6.1 Prerequisites
  12. 6.2 Configuring DynamoDB Streams
  13. 6.3 Setting Up Lambda Permissions
  14. Best Practices
  15. Troubleshooting Common Issues
  16. Future of Cross-Account Streaming
  17. Conclusion

Introduction

As businesses increasingly adopt multi-account architectures, the need for seamless data sharing across accounts becomes crucial. The recent announcement by AWS Lambda now supports cross-account access for AWS DynamoDB Streams, paving the way for a simpler, more efficient event-driven application design. By enabling such access, organizations can now centralize their event processing and share events without the cumbersome overhead of data replication, thus streamlining their operations. This guide will explore everything you need to know about this feature, from its significance to practical implementation.

Understanding AWS Lambda and DynamoDB

What is Amazon DynamoDB?

Amazon DynamoDB is a fully-managed NoSQL database service provided by AWS that offers consistent and single-digit millisecond performance at any scale. With support for key-value and document data models, DynamoDB is ideal for applications that require low-latency data access with high throughput.

Key Features of DynamoDB:

  • Scalability: Automatically scales up and down to adjust based on traffic.
  • Durability and Availability: Creates continuous backups and provides replication across multiple locations.
  • Pay-for-What-You-Use Model: Billing based on actual read/write requests.

What is AWS Lambda?

AWS Lambda is a serverless compute service that lets you run code without provisioning or managing servers. You can trigger Lambda functions in response to events, such as changes to data in DynamoDB, making it an ideal component for building event-driven architectures.

Key Features of AWS Lambda:

  • Event-Driven: Automatically runs code in response to events from various AWS services.
  • Auto-Scaling: Automatically scales depending on the number of events it processes.
  • Cost Efficiency: You pay only for the compute time that you consume.

The Significance of Cross-Account Access

Cross-account access for DynamoDB Streams is not just a convenience; it brings substantial benefits:

  • Simplifies Architecture: Reduces the need for complex setups that involve data replication.
  • Enhances Collaboration: Facilitates data sharing between different teams or partner organizations.
  • Improved Security: Resource-based policies allow for fine-grained access control.

How Cross-Account Access Works

With the new feature, developers can set up a resource-based policy on their DynamoDB Streams, allowing specific Lambda functions from different AWS accounts to interact.

Setting Resource-Based Policies

To enable cross-account access, you will need to create a resource-based policy for your DynamoDB Streams. These policies define who can access the stream and what actions they can perform.

Here’s an example policy JSON:

json
{
“Version”: “2012-10-17”,
“Statement”: [
{
“Effect”: “Allow”,
“Principal”: {
“AWS”: “arn:aws:iam:::role/”
},
“Action”: “dynamodb:DescribeStream”,
“Resource”: “arn:aws:dynamodb:::table//stream/*”
}
]
}

Creating an Event-Source Mapping

An event-source mapping connects DynamoDB Streams with your Lambda function. This mapping allows the Lambda function to listen for changes in the DynamoDB table and process those changes as events.

Use Cases for Cross-Account Access

  • Centralized Logging: Aggregate logs from multiple accounts into one service.
  • Shared Data Services: Create services that multiple AWS accounts within an organization can access.
  • Decoupled Architecture: Streamline architectures by allowing different teams to operate independently while interacting through event streams.

Implementing Cross-Account Access: Step-by-Step

Prerequisites

  • An existing AWS account with Lambda and DynamoDB set up.
  • Permissions to create and manage IAM roles and policies.

Configuring DynamoDB Streams

  1. Enable Streams:
  2. Go to your DynamoDB table.
  3. Navigate to the “Exports and streams” section.
  4. Enable DynamoDB Streams and select the desired stream view (e.g., NEW_AND_OLD_IMAGES).

Setting Up Lambda Permissions

  1. Create a New Role:
  2. Set up an IAM Role in the source account that your Lambda function will use.

  3. Attach the necessary permissions policies.

  4. Add Inline Policy:

  5. Create an inline policy to allow actions on the DynamoDB stream from the current account.

Create Event-Source Mapping

  1. AWS Management Console:
  2. Go to AWS Lambda and select your function.
  3. Click on “Add trigger” and choose “DynamoDB”.

  4. Fill out the details including the ARN of the DynamoDB stream.

  5. Using AWS CLI:

  6. Use the following command to create an Event Source Mapping:
    bash
    aws lambda create-event-source-mapping –function-name –batch-size 100 –event-source-arn

Best Practices

  • Use Tags for Management: Tag your resources for easier identification and management.
  • Monitor with CloudWatch: Set up CloudWatch Alarms for monitoring and alerting purposes.
  • Review Policies Regularly: Regularly review and update your IAM policies to ensure they remain secure and relevant.

Troubleshooting Common Issues

  • Permissions Errors: Double-check IAM roles and policies if you encounter access denied errors.
  • Event Source Mapping Issues: Ensure that your mapping is correctly set up in the Lambda console or via CLI.

Future of Cross-Account Streaming

As AWS continues to innovate, we can expect further enhancements to Lambda’s capabilities and integrations with other services, paving the way for even more efficient and robust event-driven architectures in multi-account environments.

Conclusion

Cross-account access for AWS DynamoDB Streams in Lambda represents a significant advancement in building scalable, event-driven applications. By leveraging this feature, organizations can simplify their architectures while promoting collaboration and efficiency.

Key Takeaways:

  • Cross-account access reduces operational overhead by eliminating the need for data replication.
  • Implementing this feature enhances collaboration across different teams and organizations.
  • By following best practices, you can ensure a secure and scalable architecture.

The advancement in AWS Lambda with cross-account access for DynamoDB Streams signifies a promising future for building streamlined event-driven applications.

Focus Keyphrase: AWS Lambda cross-account access for DynamoDB Streams.

This comprehensive guide aims to provide an understanding of AWS Lambda’s new feature and practical steps for leveraging it effectively. For further insights, explore other related topics such as AWS IAM Best Practices or Event-Driven Architectures with AWS.

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