Lambda payload size now at 1MB for async invocations 🚀☁️ #89

Step Functions with Q diagnosis and Kiro waitlist ends.

Oct 30, 2025

In the previous issue, Amazon ECS Managed Instances 🚀☁️ #88 we looked at the new ECS Managed instances.

That’s a powerful feature change for event-driven architectures! The increase in the asynchronous invocation payload limit from 256 KB to 1 MB fundamentally simplifies how you handle rich, contextual data in serverless workflows. While the pricing for the payload up to 256kb still remains the same per request, the payload with 256kb to 1mb would be on a model of 64kb additional request chunk, which now means you’ll be paying for the exceeding payload on a consumption basis.

What does it mean for architectures? Your Lambda triggers - EventBridge, Step Functions, S3, Kinesis Data Streams, or even another Lambda function can now send more data in the innovation, making it more efficient than the Lambda Function reading them from a data store.

⭐ Pick of the month

This month’s Pick is “AWS AppSync“.

Jaya Ganesh in the series of Getting Started with AppSync (Part 3: Lambda Resolvers) shares more about the Lambda Resolvers and how to generate signed URLs for S3 objects with GraphQL queries and mutations.

Ian Brumby’s blog Realtime Event-Driven Applications with AppSync Events and EventBridge Pipes explains how AppSync Events sits at the core of EDA and making it more resilient with EventBridge Pipes.

Jones Zachariah Noel N (Author) writes about AppSync 101, the DevX with JS resolvers for AppSync APIs and also a workaround for AppSync Subscription triggers via Lambda Functions.

🚀 AWSome content to learn from

Vadym Kazulkin in the series on Micronaut on Lambda - measures the Lambda cold and warm starts with GrallVM Native Image and compares how they are more warm Lambda invocations.

Kimberly Lu explains how you can batch process with Step Functions from distributed maps with CSV from S3 to having nested State Machines with parent-child workflows.

Thirunavukarasan Uthirapathy breaks down AWS CloudFront Functions and Function Key-Value Store with some fo the use-cases and limitations also comparing CF Functions v/s Lambda@Edge.

Ville Kärkkäinen revisits how you do you like your AWS Lambda Concurrency in 2025 from 2023, with the change in Lambda runtimes, pricing impact, configurations with memory along with workloads with S3 Express One Zone.

Ganesh M’s blog on Best Practices for Optimizing AWS Lambda Performance: Taming Cold Start in C# explains SnapStart and how C# .NET handles it with a guided strategy breakdown.

Running Untrusted Code Safely at Scale with AWS Lambda by Piotr Migdał covers the aspect of Lambda and Docker in an isolated VPC, and goes a step further to share the lessons from securing these sandboxes.

Kishor Muruganandham breaks down how a DNS Race Condition Took Down AWS DynamoDB, which eventually caused the AWS us-east-1 outage affecting other AWS Services and other products.

Marcin Sodkiewicz gets on the use-case of organization-wide EventBridge broadcasting and how the centralized bus and schema validations that EventBridge supports make it efficient for event publishers and consumers.

Jones Zachariah Noel N breaks down why observability proved to be non-negotiable in times of AWS outage, decoding the domino effect, and how observability brings better visibility for you as a customer with alerts.

⚒️ What's happening with Serverless tools, samples, and projects

Ville Kärkkäinen has published a concurrency evaluation tool for python, node, go, and other runtimes.

Om Ingale builds a aws-serverless-pos-transactions.

Workflow Development Kit (WDK) by Vercel goes live.

🎙️ Podcasts, videos and live-streams

On AWS Developers Podcast, Sébastien Stormacq and Tiffany Souterre joining with Alexis Philippart de Foy for Building Serverless MCP Servers on AWS Lambda.

Urmila Raju’s session Next-Generation AWS Step Functions: AI Integration and Advanced Orchestration