AWS outlines local emulator for cloud application testing

Amazon Web Services has announced AWS Emulator, a tool the company says allows developers to test applications against AWS APIs locally without deploying resources to its cloud.

According to an AWS News Blog post by Daniel Abib, the emulator provides a local HTTPS endpoint for the AWS Command Line Interface, software development kits and coding agents. Developers redirect their tools through environment variables, with AWS saying application code can remain unchanged.

AWS says the emulator carries no additional service fee, with charges applying to AWS resources when users deploy on AWS. Its source is available on GitHub. Linux installation uses RPM or Debian packages, while macOS and Windows users run it in Docker. AWS says it does not publish a ready-made container image, so those users must build one using the documented Dockerfile.

The emulator generates credentials, configuration files and a certificate when it starts. The setup described in the post listens on the computer’s loopback address. AWS says generated access keys begin with EMULATOR and the tool rejects requests signed with other keys. Its walkthrough also removes environment variables that could supply real AWS credentials.

Written in Rust, the emulator supports service APIs represented in AWS’s API models repository, according to the company. AWS says requests and errors have the same structure as their cloud equivalents. The supplied material does not establish how closely every service’s behaviour matches the live cloud environment.

The post demonstrates local S3 operations and a DynamoDB workflow involving the Kiro coding agent. It also describes an embedded mode for the AWS SDK for Rust, allowing tests to run within a process rather than through a separate server. AWS says each embedded instance maintains separate state, supporting parallel tests without shared buckets, tables or queues.