Lambda MicroVMs, 11 more services region-isolated, and presigned S3 URL verification

August 1, 2026 · v1.4.9

v1.4.9 adds a new Lambda MicroVMs service, extends account+region isolation to 11 more services, and tightens S3 to real AWS by verifying presigned URL signatures. It also lands Step Functions, IoT, and SNS parity fixes.

New — Lambda MicroVMs

• Lambda MicroVMs. Control-plane emulation of the AWS Lambda MicroVM API (2025-09-09): RunMicrovm, GetMicrovm, ListMicrovms, SuspendMicrovm, ResumeMicrovm, TerminateMicrovm, CreateMicrovmImage, CreateMicrovmAuthToken, and CreateMicrovmShellAuthToken. MicroVMs transition straight to RUNNING and images to CREATED (no real provisioning); state is account- and region-scoped. Reported by @wparad.
• IAM — role update parity. CreateRole and GetRole now round-trip PermissionsBoundary; PutRolePermissionsBoundary / DeleteRolePermissionsBoundary update it with AWS-shaped output and missing-role errors; and UpdateRoleDescription now returns and persists the updated role. This unblocks Terraform providers that reconcile fixed boundaries and descriptions on service roles. Contributed by @jayjanssen.

Multi-region — 11 more services

• EC2, CloudTrail, ECR, Glue, OpenSearch, WAFv2, and Backup now isolate state by account and region, matching real AWS and joining IoT and AppSync Events from 1.4.8. Same-name resources in different regions no longer collide. WAFv2 homes CLOUDFRONT-scope resources in us-east-1 with global-segment ARNs. Persisted state carries a versioned regional schema (on-disk format v3) that an older binary refuses rather than misreads; legacy resources migrate by ARN region. Contributed by @Areson.
• ACM, Elastic Load Balancing (ALB/NLB), MediaConnect, and RDS Data now isolate state by account and region as well, using the same versioned regional schema and by-ARN legacy migration.

Changed — S3 presigned URL verification

• Presigned S3 URL signatures are now verified. Presigned SigV4 URLs were accepted without checking the signature, so a URL signed with bogus credentials, or one whose signed headers (content-type, content-length, …) were changed after signing, still succeeded — passing against MiniStack but failing against real S3. Presigned URLs are now verified against the server credential (AWS_SECRET_ACCESS_KEY, default test); a bad signature or tampered signed header returns 403 SignatureDoesNotMatch, matching real S3. Header-signed and anonymous requests are unaffected. Sign presigned URLs with the test secret (or set the server's AWS_SECRET_ACCESS_KEY). Reported by @BartekAndree.

Fixes

• SNS — filter policies now match String.Array message attributes. A FilterPolicy compared the raw StringValue of a String.Array attribute (e.g. ["example.created"]) against the policy values, so array attributes never matched. Each element of a String.Array attribute is now evaluated separately, matching AWS. Reported by @cabrerafd.
• S3 — GetBucketEncryption now returns the default SSE-S3 configuration. A bucket with no explicit encryption returned ServerSideEncryptionConfigurationNotFoundError, but since 5 January 2023 every S3 bucket has default SSE-S3 encryption, so real S3 returns an AES256 configuration. GetBucketEncryption now returns that default rather than the error. Reported by @rsariyev-nav.
• Step Functions — aws-sdk integrations for Query-protocol services sent malformed requests. The shared adapter numbered EC2 list parameters under the wrong wire names and passed the form body as a string rather than bytes, so calls such as aws-sdk:ec2:describeInstances and aws-sdk:sqs:getQueueAttributes failed or silently dropped parameters. EC2 list parameters are now numbered under their botocore wire names, the body is encoded to bytes, GetQueueAttributes returns the SDK Attributes map, and IsTruncated is emitted as a boolean. Contributed by @bandle.
• Step Functions — wildcard path projections now resolve. JSONPath wildcard ([*]) projections in ASL returned incorrect results. Contributed by @felixp-square.
• IoT — topic-rule Lambda action resolved the function in the wrong region. After IoT state became region-scoped, a topic rule invoking a Lambda action looked the function up in the request region rather than the function's own, so cross-region rule targets missed. Contributed by @Areson.
• EC2 — ModifySecurityGroupRules is now implemented. The action previously returned InvalidAction: Unknown EC2 action: ModifySecurityGroupRules. Contributed by @staranto.
• Cognito — CUSTOM_AUTH now honors Cognito-owned SRP challenges and passes ClientMetadata to DefineAuth. Amplify CUSTOM_WITH_SRP failed with USER_ID_FOR_SRP was not found; the flow now records SRP_A success, returns built-in PASSWORD_VERIFIER challenge parameters, and continues the custom-auth session so MFA CUSTOM_CHALLENGE rounds still work. Contributed by @onelshina.
• Step Functions — aws-sdk:s3:headObject dropped the object's user Metadata map. The dispatcher now collects x-amz-meta-* response headers into a Metadata map with the prefix stripped, so ASL reading $.Metadata.<key> works. Contributed by @michael-denyer.

Upgrade

docker pull ministackorg/ministack:1.4.9
docker run -d -p 4566:4566 ministackorg/ministack:1.4.9

Or pin in compose.yaml:

services:
  ministack:
    image: ministackorg/ministack:1.4.9
    ports:
      - "4566:4566"