Winterbaume

Stateful AWS service mocking for aws-sdk-rust. Intercepts SDK HTTP calls in-process and routes them to in-memory service backends that simulate real AWS behavior with persistent state. No network I/O required.

Inspired by Python's moto.

Supported Services

Service	Crate	Protocol
ACM	winterbaume-acm	awsJson1.1
CloudFront	winterbaume-cloudfront	REST-XML
CloudWatch	winterbaume-cloudwatch	awsQuery
CloudWatch Logs	winterbaume-logs	awsJson1.1
Cognito Identity Provider	winterbaume-cognitoidp	awsJson1.1
DynamoDB	winterbaume-dynamodb	awsJson1.0
ECR	winterbaume-ecr	awsJson1.1
ECS	winterbaume-ecs	awsJson1.1
EKS	winterbaume-eks	REST-JSON
ELBv2	winterbaume-elbv2	awsQuery
EventBridge	winterbaume-events	awsJson1.1
Firehose	winterbaume-firehose	awsJson1.1
IAM	winterbaume-iam	awsQuery
Kinesis	winterbaume-kinesis	awsJson1.1
KMS	winterbaume-kms	awsJson1.1
Lambda	winterbaume-lambda	REST-JSON
Organizations	winterbaume-organizations	awsJson1.1
Route 53	winterbaume-route53	REST-XML
S3	winterbaume-s3	REST-XML
Secrets Manager	winterbaume-secretsmanager	awsJson1.1
SES v2	winterbaume-ses	REST-JSON
SNS	winterbaume-sns	awsQuery
SQS	winterbaume-sqs	awsJson1.0
SSM	winterbaume-ssm	awsJson1.1
Step Functions	winterbaume-stepfunctions	awsJson1.0
STS	winterbaume-sts	awsQuery

Usage

Library mode (in-process)

use winterbaume_core::MockAws;
use winterbaume_sts::StsService;
use winterbaume_iam::IamService;
use winterbaume_s3::S3Service;

let mock = MockAws::builder()
    .with_service(StsService::new())
    .with_service(IamService::new())
    .with_service(S3Service::new())
    .build();

let config = aws_config::defaults(BehaviorVersion::latest())
    .http_client(mock.http_client())
    .credentials_provider(mock.credentials_provider())
    .region("us-east-1")
    .load()
    .await;

let sts = aws_sdk_sts::Client::new(&config);
let resp = sts.get_caller_identity().send().await.unwrap();
assert_eq!(resp.account(), Some("123456789012"));

Standalone HTTP server

For non-Rust clients, winterbaume-server provides a standalone HTTP server:

cargo run -p winterbaume-server -- --host 127.0.0.1 --port 5555

Point the AWS SDK at it:

export AWS_ENDPOINT_URL=http://localhost:5555
aws s3 mb s3://my-bucket

Architecture

• winterbaume-core -- shared infrastructure: MockAws builder, MockService trait, per-account/region state management, HTTP client/connector bridge.
• winterbaume-{service} -- each service crate implements MockService with its own protocol handling and in-memory state.
• winterbaume-server -- hyper-based HTTP server that registers all service backends.

State is partitioned per account ID and region, matching real AWS isolation semantics.

License

Apache-2.0. See LICENSE for the full text.

This project vendors moto (Copyright 2012 Steve Pulec, Apache-2.0) as a reference implementation under vendor/moto/. See NOTICE for third-party attribution details.