Aws

Name: Aws
Author: vercel-labs

vercel-labs/emulate

141 installs
1.5k repo stars
Updated July 20, 2026
vercel-labs/emulate

Local AWS emulator for S3, SQS, IAM, and STS integration testing without real cloud resources.

About

Emulated AWS cloud services for local development covering S3 bucket and object operations, SQS queues, IAM roles and policies, and STS token exchange. Starts with npx emulate --service aws. Documents endpoint configuration so AWS SDK clients point at localhost, seed data for buckets and queues, and in-memory persistence across test runs. Enables integration tests that exercise S3 uploads, SQS message handling, and IAM-assumed role flows without incurring AWS charges or requiring cloud credentials beyond emulator defaults.

Local emulation of S3, SQS, IAM, and STS AWS services
AWS SDK endpoint override for localhost testing
Seed configuration for buckets, queues, and IAM entities
In-memory persistence for integration test isolation
No real AWS charges or production credential requirements

Aws by the numbers

141 all-time installs (skills.sh)
+4 installs in the week ending Jul 27, 2026 (Skillselion tracking)
Ranked #901 of 2,153 Testing & QA skills by installs in the Skillselion catalog
Security screen: HIGH risk (skills.sh audit)
Data as of Aug 4, 2026 (Skillselion catalog sync)

At a glance

aws capabilities & compatibility

Capabilities: emulate s3 · emulate sqs · emulate iam sts · seed aws resources
Works with: aws
Use cases: testing · api development
Runs: Runs locally

From the docs

What aws says it does

Emulated AWS cloud services (S3, SQS, IAM, STS) for local development and testing.

SKILL.md

npx skills add https://github.com/vercel-labs/emulate --skill aws

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Installs	141
repo stars	★ 1.5k
Security audit	2 / 3 scanners passed
Last updated	July 20, 2026
Repository	vercel-labs/emulate ↗

How do I test AWS S3 or SQS integrations locally?

Run emulated AWS services locally including S3, SQS, IAM, and STS for development and integration testing without real AWS accounts.

Who is it for?

Developers testing AWS integrations in CI or local dev without cloud accounts.

Skip if: Production AWS administration or services beyond emulated S3 SQS IAM STS.

When should I use this skill?

User needs local AWS API endpoints, S3 bucket testing, or SQS message flows.

What you get

AWS SDK calls hit local emulator with inspectable S3, SQS, IAM, and STS state.

Files

SKILL.mdMarkdownGitHub ↗

AWS Emulator

S3, SQS, IAM, and STS emulation with AWS SDK-compatible S3 paths and query-style SQS/IAM/STS endpoints. All state is in-memory, and responses use AWS-compatible XML.

Start

# AWS only
npx emulate --service aws

# Default port (when run alone)
# http://localhost:4000

Or programmatically:

import { createEmulator } from 'emulate'

const aws = await createEmulator({ service: 'aws', port: 4006 })
// aws.url === 'http://localhost:4006'

Auth

Pass tokens as Authorization: Bearer <token>. Scoped permissions use s3:*, sqs:*, iam:*, sts:* patterns.

curl http://localhost:4006/ \
  -H "Authorization: Bearer test_token_admin"

Pointing Your App at the Emulator

Environment Variable

AWS_EMULATOR_URL=http://localhost:4006

AWS SDK v3

import { S3Client } from '@aws-sdk/client-s3'

const s3 = new S3Client({
  endpoint: process.env.AWS_EMULATOR_URL,
  region: 'us-east-1',
  credentials: {
    accessKeyId: 'AKIAIOSFODNN7EXAMPLE',
    secretAccessKey: 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
  },
  forcePathStyle: true,
})

import { SQSClient } from '@aws-sdk/client-sqs'

const sqs = new SQSClient({
  endpoint: `${process.env.AWS_EMULATOR_URL}/sqs`,
  region: 'us-east-1',
  credentials: {
    accessKeyId: 'AKIAIOSFODNN7EXAMPLE',
    secretAccessKey: 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
  },
})

import { IAMClient } from '@aws-sdk/client-iam'

const iam = new IAMClient({
  endpoint: `${process.env.AWS_EMULATOR_URL}/iam`,
  region: 'us-east-1',
  credentials: {
    accessKeyId: 'AKIAIOSFODNN7EXAMPLE',
    secretAccessKey: 'wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY',
  },
})

Seed Config

aws:
  region: us-east-1
  s3:
    buckets:
      - name: my-app-bucket
      - name: my-app-uploads
        region: eu-west-1
  sqs:
    queues:
      - name: my-app-events
      - name: my-app-dlq
        visibility_timeout: 60
      - name: my-app-orders.fifo
        fifo: true
  iam:
    users:
      - user_name: developer
        create_access_key: true
      - user_name: readonly-user
    roles:
      - role_name: lambda-execution-role
        description: Role for Lambda function execution
        assume_role_policy: '{"Version":"2012-10-17","Statement":[{"Effect":"Allow","Principal":{"Service":"lambda.amazonaws.com"},"Action":"sts:AssumeRole"}]}'

Default seed (always created): S3 bucket emulate-default, SQS queue emulate-default-queue, IAM user admin with access key pair (AKIAIOSFODNN7EXAMPLE / wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY).

API Endpoints

S3

S3 routes use root paths matching the real AWS S3 wire format. Legacy /s3/ prefixed paths are also supported.

# List all buckets
curl http://localhost:4006/ \
  -H "Authorization: Bearer $TOKEN"

# Create bucket
curl -X PUT http://localhost:4006/my-bucket \
  -H "Authorization: Bearer $TOKEN"

# Delete bucket (must be empty)
curl -X DELETE http://localhost:4006/my-bucket \
  -H "Authorization: Bearer $TOKEN"

# Head bucket (check existence, get region)
curl -I http://localhost:4006/my-bucket \
  -H "Authorization: Bearer $TOKEN"

# List objects (with prefix, delimiter, pagination)
curl "http://localhost:4006/my-bucket?prefix=uploads/&delimiter=/&max-keys=100" \
  -H "Authorization: Bearer $TOKEN"

# Put object
curl -X PUT http://localhost:4006/my-bucket/path/to/file.txt \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: text/plain" \
  -H "x-amz-meta-author: test" \
  --data-binary "file contents"

# Get object
curl http://localhost:4006/my-bucket/path/to/file.txt \
  -H "Authorization: Bearer $TOKEN"

# Head object (metadata only)
curl -I http://localhost:4006/my-bucket/path/to/file.txt \
  -H "Authorization: Bearer $TOKEN"

# Delete object
curl -X DELETE http://localhost:4006/my-bucket/path/to/file.txt \
  -H "Authorization: Bearer $TOKEN"

# Copy object
curl -X PUT http://localhost:4006/dest-bucket/copy.txt \
  -H "Authorization: Bearer $TOKEN" \
  -H "x-amz-copy-source: /source-bucket/original.txt"

SQS

All SQS operations use POST /sqs/ with Action as a form-urlencoded parameter.

# Create queue
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "Action=CreateQueue&QueueName=my-queue"

# Create queue with attributes
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "Action=CreateQueue&QueueName=my-queue&Attribute.1.Name=VisibilityTimeout&Attribute.1.Value=30"

# List queues
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=ListQueues"

# List queues with prefix filter
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=ListQueues&QueueNamePrefix=my-"

# Get queue URL
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=GetQueueUrl&QueueName=my-queue"

# Get queue attributes
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=GetQueueAttributes&QueueUrl=<queue_url>"

# Send message
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=SendMessage&QueueUrl=<queue_url>&MessageBody=Hello+World"

# Send message with attributes
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=SendMessage&QueueUrl=<queue_url>&MessageBody=Hello&MessageAttribute.1.Name=type&MessageAttribute.1.Value.DataType=String&MessageAttribute.1.Value.StringValue=greeting"

# Receive messages
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=ReceiveMessage&QueueUrl=<queue_url>&MaxNumberOfMessages=5"

# Delete message
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=DeleteMessage&QueueUrl=<queue_url>&ReceiptHandle=<receipt_handle>"

# Purge queue
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=PurgeQueue&QueueUrl=<queue_url>"

# Delete queue
curl -X POST http://localhost:4006/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=DeleteQueue&QueueUrl=<queue_url>"

IAM

All IAM operations use POST /iam/ with Action as a form-urlencoded parameter.

# Create user
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=CreateUser&UserName=new-user"

# Get user
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=GetUser&UserName=new-user"

# List users
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=ListUsers"

# Delete user
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=DeleteUser&UserName=new-user"

# Create access key
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=CreateAccessKey&UserName=developer"

# List access keys
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=ListAccessKeys&UserName=developer"

# Delete access key
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=DeleteAccessKey&UserName=developer&AccessKeyId=AKIA..."

# Create role
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=CreateRole&RoleName=my-role&AssumeRolePolicyDocument={}"

# Get role
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=GetRole&RoleName=my-role"

# List roles
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=ListRoles"

# Delete role
curl -X POST http://localhost:4006/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=DeleteRole&RoleName=my-role"

STS

All STS operations use POST /sts/ with Action as a form-urlencoded parameter.

# Get caller identity
curl -X POST http://localhost:4006/sts/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=GetCallerIdentity"

# Assume role
curl -X POST http://localhost:4006/sts/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=AssumeRole&RoleArn=arn:aws:iam::123456789012:role/my-role&RoleSessionName=my-session"

Inspector

# HTML dashboard (shows S3, SQS, IAM state)
curl http://localhost:4006/_inspector?tab=s3
curl http://localhost:4006/_inspector?tab=sqs
curl http://localhost:4006/_inspector?tab=iam

Common Patterns

Upload and Retrieve an Object

TOKEN="test_token_admin"
BASE="http://localhost:4006"

# Create bucket
curl -X PUT $BASE/my-data \
  -H "Authorization: Bearer $TOKEN"

# Upload file
curl -X PUT $BASE/my-data/config.json \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/json" \
  --data-binary '{"key": "value"}'

# Download file
curl $BASE/my-data/config.json \
  -H "Authorization: Bearer $TOKEN"

Send and Receive SQS Messages

TOKEN="test_token_admin"
BASE="http://localhost:4006"

# Get queue URL
QUEUE_URL=$(curl -s -X POST $BASE/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=GetQueueUrl&QueueName=emulate-default-queue" | grep -oP '<QueueUrl>\K[^<]+')

# Send message
curl -X POST $BASE/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=SendMessage&QueueUrl=$QUEUE_URL&MessageBody=Hello+from+emulate"

# Receive messages
curl -X POST $BASE/sqs/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=ReceiveMessage&QueueUrl=$QUEUE_URL&MaxNumberOfMessages=1"

Create IAM User with Access Key

TOKEN="test_token_admin"
BASE="http://localhost:4006"

# Create user
curl -X POST $BASE/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=CreateUser&UserName=ci-user"

# Generate access key
curl -X POST $BASE/iam/ \
  -H "Authorization: Bearer $TOKEN" \
  -d "Action=CreateAccessKey&UserName=ci-user"