Announcing the LocalStack for AWS 4.13 Release

Introduction

We’re happy to announce the release of LocalStack for AWS 4.13, including important improvements to support and parity across a number of key services includes Lambda, ECS, Route 53 and API Gateway, as well as a ton of smaller but important enhancements and fixes that continue to improve AWS and IaC framework parity. Read on for all the details!

Get your free LocalStack account to access the latest features and enhancements in LocalStack for AWS 4.13!

How to upgrade?

To upgrade to LocalStack for AWS 4.13 using the LocalStack CLI, run:

localstack update all

If using Docker CLI or Docker Compose, update the Docker image:

docker pull localstack/localstack:4.13.0 # Community Edition

docker pull localstack/localstack-pro:4.13.0 # Pro Edition

What’s new in LocalStack for AWS 4.13?

• Introduction
• How to upgrade?
• What’s new in LocalStack for AWS 4.13?
  • .NET 10 Lambda Runtime
  • ECS Emulation Improvements
  • Better Routing Parity
  • Miscellaneous
• Deprecations
• Conclusion

.NET 10 Lambda Runtime

At LocalStack, we try to ensure that you have access to the latest features and updates released by AWS as soon as possible within LocalStack for AWS. On January 8, AWS announced the availability of the .NET 10 runtime for AWS Lambda.

.NET 10 includes runtime and compiler optimizations that can help shrink the executable size and improve startup performance. It also includes new file-based apps that let you create .NET apps from a single C# file without creating a traditional project file. This type of self-contained source file is ideal for working with .NET within Lambdas.

We’re excited to share that the .NET 10 runtime was also available within localstack@latest only days after the release was announced by AWS and is also part of the official 4.13 release. This means you can build and test your .NET 10 based Lambdas, including file-based apps or using .NET 10 with Powertools for AWS Lambda (.NET) on your local machine or within CI/CD.

ECS Emulation Improvements

In addition to keeping up with changes released by AWS, we are constantly striving to offer the most complete emulation across the services we support. Along these lines, LocalStack for AWS 4.13 includes several improvements to our Amazon Elastic Container Service (ECS) support:

• Added support for the repositoryCredentials parameter in an ECS task definition allowing ECS to pull images from registries that require authentication. This is currently only implemented for Docker executor, with support for the Kubernetes executor forthcoming.

• Added an initial implementation to support the cpu and memory values in the container configuration of a task definition. For example:

  {
    "containerDefinitions": [
      {
        "name": "my-app",
        "image": "nginx:latest",
        "cpu": 256,
        "memory": 512
      }
    ]
  }

• LocalStack for AWS support for ECS previously had synchronous startup logic in LocalStack that blocked API responses during image pulls, which could cause issues in instances where image pulls took a long time. The new behavior as of 4.13 makes deployment completion asynchronous by moving post-start work into a background routine, eliminating these issues.

Better Routing Parity

LocalStack for AWS 4.13 includes a couple of important parity enhancements that impact both Amazon Route 53 and API Gateway:

• Route 53 now supports weighted routing, which lets you associate multiple resources with a domain or subdomain and specify how much traffic is routed to each resource via a relative weight. You can do this by specifying multiple values for a ResourceRecordSet, and traffic will be randomly directed to those in correlation to the specified weights. Note that this will currently only work for an AliasTarget targeting resource internal to LocalStack itself and not for external IPs.
• We have overhauled how API Gateway Custom Domains and Route53 routing interact to ensure that complex networking setups, such as applications spanning multiple regions, have better parity with AWS.
  • You can now use the same custom domain name across different regions without them overwriting each other as LocalStack for AWS will now correctly treat these as regional resources.
  • If you have a domain registered in both Route 53 and API Gateway, LocalStack for AWS now correctly applies Route53’s routing logic (like weighted routing) before passing the request to API Gateway.

Miscellaneous

• Added support for CreateServerlessCache within ElastiCache.
• Added two new configuration options (EC2_LIBVIRT_NETWORK and EC2_LIBVIRT_POOL) to allow the name of the Libvirt network and/or Libvirt storage pool to be customized. An additional configuration variable (EC2_REFERENCE_DOMAIN) that can already defined Libvirt domain whose configuration LocalStack will copy into all new VMs it creates.
• Previously, when creating an Amazon Managed Streaming for Apache Kafka (MSK) cluster and attaching a custom configuration, the configuration was successfully attached but its settings are not applied at runtime. As of LocalStack for AWS 4.13, the attached MSK configuration will be applied to the cluster, and its parameters (e.g., num.partitions, min.insync.replicas, etc.) will affect the runtime behavior as expected.
• Fixed an issue where creating an AppSync API key with Terraform would fail since the generated expires and deletes would be float.
• Added support for the instance target type in Network Load Balancers.
• Fixed an issue where a CloudFormation (CFN) resource operation not supported by LocalStack would produce an incorrect InternalFailure error that did not clearly indicate the specific CFN resource support that is missing.
• Added support for the AWS::RDS::DBProxyEndpoint in CloudFormation. The resource type is already supported by LocalStack for AWS’s RDS service.
• Added new configuration variables to enable users to ignore specific unsupported resource types in CloudFormation. CFN_IGNORE_UNSUPPORTED_TYPE_CREATE and CFN_IGNORE_UNSUPPORTED_TYPE_UPDATE take a comma-separated list of resource type names that CloudFormation will ignore on stack creation and update respectively.
• Fixed missing metadata in API Gateway VPC Links to ensure LocalStack for AWS now correctly populates fields like targetArns, name, and description for VPC Links.

Deprecations

This release included a number of service deprecations in line with changes to AWS offerings. The following services have been removed in alignment with end of support announcements from AWS:

• IoT Analytics (retired effective December 15, 2025)
• Elemental MediaStore (retired effective November 13, 2025)
• Elastic Transcoder (retired effective November 13, 2025)

In addition, the following AirFlow versions for Amazon Managed Workflows for Apache Airflow (MWAA) were retired as of December 30, 2025 and removed from support in LocalStack for AWS:

• 2.4.3
• 2.5.1
• 2.6.3

Finally, please note that our v1 provider for AWS Glue has been deprecated. The new behavior will default to the v2 provider and the GLUE_JOB_EXECUTOR_PROVIDER environment variable has been deprecated.

Conclusion

LocalStack for AWS 4.13 includes key enhancements to a variety of services including Lambda, ECS, Route53, API Gateway and more as well as a number of small but important “quality of life” improvements to our IaC support in both CloudFormation and Terraform. Upgrade to LocalStack for AWS 4.13 today to give all the new capabilities a try.