DEV Community

kawasaki031677
kawasaki031677

Posted on

Getting Started with LocalStack - Testing CloudFormation and S3 Locally

#aws #s3 #cloudformation #localstack

What is LocalStack?

LocalStack is a tool that allows you to simulate AWS services in a local environment. You can test and develop resources like S3 and Lambda without using a cloud environment. This time, I'll demonstrate using CloudFormation to create an S3 bucket with LocalStack.

Running It Locally

Create a docker-compose.yml file with the following content:

version: '3.8'

services:
  localstack:
    image: localstack/localstack
    ports:
      - "4566:4566"  # LocalStack unified endpoint
    environment:
      - SERVICES=cloudformation,s3,dynamodb  # Specify services to enable as comma-separated values
      - DEBUG=1  # Enable debug mode
Enter fullscreen mode Exit fullscreen mode

Next, run the following command to start LocalStack:

$ docker-compose up -d
Enter fullscreen mode Exit fullscreen mode

Deploying CloudFormation

Let me write a sample CloudFormation template:

AWSTemplateFormatVersion: '2010-09-09'
Resources:
  MyBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: my-localstack-bucket
Enter fullscreen mode Exit fullscreen mode

Now, let's deploy it to LocalStack:

$ aws --endpoint-url=http://localhost:4566 cloudformation create-stack --stack-name myteststack --template-body file://template.yml
{
    "StackId": "arn:aws:cloudformation:ap-northeast-1:000000000000:stack/myteststack/8320a915"
}
Enter fullscreen mode Exit fullscreen mode

Alert: Be careful to always specify the --endpoint-url parameter. Without it, the deployment will go to your production environment.

Verifying the Deployment

Let's verify that S3 was created successfully:

$ aws --endpoint-url=http://localhost:4566 s3 ls 
2025-09-23 23:48:30 my-localstack-bucket
Enter fullscreen mode Exit fullscreen mode

Thoughts

It's convenient to be able to create and test resources without touching the actual cloud environment. If you're developing with CloudFormation, incorporating LocalStack into your CI/CD pipeline could enable automated testing before deployment.

Top comments (0)