Introduction

Amazon Web Services (AWS) Lambda is a serverless compute service that allows you to run code without provisioning or managing servers. On the other hand, AWS Command Line Interface (CLI) is a unified tool that enables you to manage your AWS services from a terminal. Sometimes, there arises a need to call AWS CLI commands directly from within an AWS Lambda function to leverage CLI utilities, especially when dealing with complex scripting needs.

This article details how to call AWS CLI from within an AWS Lambda function, explores the technical aspects of its execution, and provides examples to facilitate understanding.

Prerequisites

Before delving into the setup, ensure you have the following:

• An AWS account with permissions to create and invoke Lambda functions.
• AWS CLI, if executing any commands locally for testing.
• Basic understanding of AWS Lambda and IAM permissions.

Setting Up AWS CLI in Lambda

Using AWS CLI within a Lambda function might seem challenging since AWS Lambda does not come preinstalled with AWS CLI. However, you can bundle the CLI within a Lambda deployment package.

Step-by-Step Guide

1. Create a Deployment Package: The deployment package will include the AWS CLI binaries, any dependencies, and your Lambda function code.
   • Install AWS CLI: Install AWS CLI locally to have the necessary binaries ready for use in Lambda. This can be achieved using pip:
   • Bundle the CLI: Once you have the `awscli` folder under `package`, create a zip file including this folder. Add your Lambda function code to the zip as well:

• Lambda Limits: Be aware of Lambda's execution limits, including runtime duration (up to 15 minutes), memory (from 128 MB to 10,240 MB), and package size (up to 50 MB zipped).
• Error Handling: Always include error handling in your Lambda function code to manage failed CLI calls gracefully.
• Security: Keep security in mind, especially regarding sensitive data and credentials. Use AWS Identity and Access Management (IAM) properly to restrict permissions.
• Testing Locally: You can simulate Lambda environments locally using tools like AWS SAM CLI or Docker to thoroughly test CLI calls.