[AWS] DevTools Evangelism: Infrastructure Composer Edition

Source: Dev.to

Introduction

This article introduces AWS Infrastructure Composer, a visual tool that helps you work with CloudFormation and AWS SAM templates. It is part of the Japan AWS Top Engineers Advent Calendar 2025 and demonstrates how to create, edit, and deploy a simple API built with API Gateway and Lambda.

Prerequisites

• Windows (the author used the Windows installer for SAM CLI)
• An AWS account with appropriate permissions
• VS Code installed

Installing the required tools

1. AWS Toolkit for VS Code – install the extension from the VS Code marketplace.

2. AWS SAM CLI – follow the official installation guide:
   https://docs.aws.amazon.com/ja_jp/serverless-application-model/latest/developerguide/install-sam-cli.html

   sam --version

3. Infrastructure Composer – once the AWS Toolkit is installed, open a YAML file in VS Code, right‑click, and select “Open with Infrastructure Composer”.

Creating a sample application with SAM

sam init

Choose the HelloWorldExample template, which already contains a basic configuration.

Building the application

sam build

Configuring AWS credentials

aws configure sso

Enter the access key ID, secret access key, and session token obtained from the AWS Access Portal.

Deploying the application

sam deploy --guided

You will be prompted for stack name, region, and other settings. Follow the prompts or refer to the official guide:
https://docs.aws.amazon.com/ja_jp/serverless-application-model/latest/developerguide/serverless-getting-started-hello-world.html

After deployment, verify the stack in the AWS CloudFormation console.

Modifying the Lambda timeout

To change the Lambda timeout, edit the SAM template (or use Infrastructure Composer’s visual editor) and then repeat the build and deploy steps:

sam build
sam deploy --guided

The new timeout value will be reflected in the AWS Lambda console.

Using Infrastructure Composer visually

When you open a CloudFormation or SAM template in the AWS console, you’ll see a “View in Infrastructure Composer” button. In VS Code, the extension provides a drag‑and‑drop UI with cards (called extended components) that let you define properties without writing raw YAML/JSON.

Conclusion

AWS Infrastructure Composer makes Infrastructure‑as‑Code (IaC) easier to understand and maintain by providing a visual layer on top of traditional text‑based templates. It works with both serverless and non‑serverless services, streamlining the development workflow for AWS developers.

Further reading

• Official AWS Serverless Application Model documentation: https://docs.aws.amazon.com/ja_jp/serverless-application-model/latest/developerguide/what-is-sam.html
• Previous article on Infrastructure Composer: https://dev.to/aws-builders/aws-i-want-to-tell-you-how-good-infrastructurecomposer-is-devtools-5bj0