Introduction

AWS Lambda is a serverless compute service that runs your code in response to events and automatically manages the underlying compute resources. One of the powerful capabilities of AWS Lambda is its ability to be invoked from another Lambda function. This is particularly useful in scenarios requiring the separation of concerns, asynchronous processing, or when chaining functions for complex workflows. This article explores how to invoke one AWS Lambda function from another Lambda function asynchronously, complete with technical explanations and examples.

Understanding Asynchronous Invocation

An asynchronous invocation of an AWS Lambda function means that the calling function invokes the target function and continues execution without waiting for the target function to complete. This is useful when you want to offload processing and continue executing other tasks, thus improving the efficiency of your Lambda function.

Benefits of Asynchronous Invocation

• Non-blocking Execution: The calling Lambda function sends an invocation request and continues its processing without waiting for a response.
• Decoupled Architecture: Keeps your architecture loosely coupled, which aids in scalability and maintenance.
• Improved Performance: Frees up the calling Lambda function to perform other tasks, potentially leading to faster execution times for your application.

Technical Explanation

To invoke a Lambda function from another Lambda function asynchronously, you can use the AWS SDK for the language you are working in (e.g., Node.js, Python, etc.). When you invoke a function asynchronously, use the InvocationType parameter set to Event .

Step-by-Step Guide for Node.js

1. Set Up IAM Permissions: Ensure the calling Lambda has permissions to invoke the target Lambda. Attach the AWSLambdaRole policy to the role of the calling Lambda function with permission to invoke the specific Lambda function.
2. Install AWS SDK (if using a custom runtime or application): AWS SDK is pre-installed in the AWS Lambda environment, but if you're using a special setup, ensure it's available.
3. Write the Lambda Caller Code:

• Decouple Tasks: Offload long-running tasks to separate Lambda functions.
• Data Processing Pipelines: Assemble data processing pipelines with distinct stages handled by different functions.
• Event-Driven Architectures: Enhance responsiveness and throughput in applications designed around event-driven patterns.