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localstack

💻 A fully functional local AWS cloud stack. Develop and test your cloud & Serverless apps offline

localstack/localstack·

65k4.6kPythonNOASSERTION

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awscloudcontinuous-integrationdeveloper-toolslocalstackpython+1

Last updated 6 days ago

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NewDecember 11, 2025

v4.12.0

Summary

LocalStack 4.12 is now available! This release introduces Lambda Managed Instances, enhanced Step Functions unit testing capabilities, expanded Glue API support with user-defined functions and column statistics, and Network Load Balancer TCP listener emulation. Additional enhancements include EventBridge Pipes input transformation, Application Load Balancer HTTPS targets, improved IAM policy simulation, and updates across S3 Tables, CloudWatch Logs, and multiple AWS services.

AWS Features

LocalStack now supports Lambda Managed Instances, a new Lambda execution mode that allows for predictable pricing when handling a high volume of Lambda invocations. Learn more in our blog post.
LocalStack now provides comprehensive support for unit testing AWS Step Functions via enhanced TestState API capabilities. Learn more in our .

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Upgraded the kinesis-mock version from 0.5.1 to 0.5.2.
Added support in CloudFormation v2 for List<AWS::EC2::SubnetId> template parameters.
Added support for additional RSA key lengths and several EC key types in ACM certificates.
Added support for the EU LocationConstraint in the S3 CreateBucket operation.
Added support for Airflow 3.0.6 in Managed Workflows for Apache Airflow (MWAA) provider. (🌟 ultimate)
Added support for the GetInstanceUefiData API in the EC2 provider. (🌟 base)
Implemented support for specifying Tags during the S3 CreateBucket operation, and added support for the TagCount field in HeadObject responses.
Added configurable wait-time controls for CloudFormation resource polling (CFN_NO_WAIT_ITERATIONS) and reduced default sleep intervals, meaning that deploy times for large stacks should be reduced.
Added configuration options to customise the Libvirt network (EC2_LIBVIRT_NETWORK) and storage pool (EC2_LIBVIRT_POOL) used by EC2, instead of assuming the default names. (🌟 enterprise)
Cognito now supports enforcing HTTPS in OAuth and federated login flows by honouring USE_SSL=1, ensuring all generated authentication URLs use https://. (🌟 base)
Added support for ECS Managed EC2 Instances capacity providers, including CRUD operations, improved status responses, and validation during task execution. (🌟 base)
Added support for the following S3 Control tagging operations for S3 buckets:
- ListTagsForResource
- TagResource
- UntagResource
Added support for the ListLogGroups operation in CloudWatch Logs.
EventBridge Pipes now supports input transformation for enrichment, including proper handling of JSON arrays and quote stripping for plain text templates. (🌟 ultimate)
Application Load Balancers now support HTTPS targets in target groups, with the load balancer skipping SSL verification for HTTPS targets, matching AWS behavior where self-signed certificates are accepted. (🌟 base)
Improved the IAM SimulatePrincipalPolicy operation to use the IAM Enforcement Engine, providing more accurate policy evaluation decisions. Support for roles and groups as principals has been added. (🌟 base)
Network Load Balancers now support TCP listener emulation, enabling basic NLB functionality for local testing. A new proxy manager handles the creation and lifecycle of TCP proxies for NLB listeners. (🌟 base)
LocalStack’s S3 Tables provider now includes the following enhancements: (🌟 ultimate)
- Added support for the ListTagsForResource API.
- Added support for encryption configuration APIs at both bucket and table levels. Actual encryption enforcement is not yet implemented.
Added support for managing user-defined functions in Glue with the following APIs: (🌟 ultimate)
- CreateUserDefinedFunction
- GetUserDefinedFunction
- UpdateUserDefinedFunction
- DeleteUserDefinedFunction
- GetUserDefinedFunctions
Added support for managing column statistics for tables in Glue with the following APIs: (🌟 ultimate)
- UpdateColumnStatisticsForTable
- GetColumnStatisticsForTable
- DeleteColumnStatisticsForTable

Update banner on README.md by @remotesynth in https://github.com/localstack/localstack/pull/13421
S3: fix change in behavior in CreateBucketConfiguration by @bentsku in https://github.com/localstack/localstack/pull/13427
S3: add support for Tags in CreateBucket by @bentsku in https://github.com/localstack/localstack/pull/13428
S3: support TagCount in HeadObject by @bentsku in https://github.com/localstack/localstack/pull/13429
Fix version evaluation of boto3 in asf update action by @silv-io in https://github.com/localstack/localstack/pull/13442
chore: define explicit state containers for providers by @bentsku in https://github.com/localstack/localstack/pull/13423
Pass DockerHub credentials to test containers by @sannya-singal in https://github.com/localstack/localstack/pull/13434
Lambda: Validate capacity provider in create_function by @anisaoshafi in https://github.com/localstack/localstack/pull/13445
Lambda: Raise error when function added a capacity provider by @anisaoshafi in https://github.com/localstack/localstack/pull/13447
chore: define rest of explicit state containers for providers by @bentsku in https://github.com/localstack/localstack/pull/13433
update kinesis-mock from 0.5.1 to 0.5.2 by @alexrashed in https://github.com/localstack/localstack/pull/13448
fix/external client CA bundle by @cloutierMat in https://github.com/localstack/localstack/pull/13451
[SFN][TestState] Make roleArn optional by @tiurin in https://github.com/localstack/localstack/pull/13459
[SFN][TestState] Fix state context tests MA/MR run failure by @tiurin in https://github.com/localstack/localstack/pull/13460
CFn: configure wait time for polling resources by @simonrw in https://github.com/localstack/localstack/pull/13455
[SFN][TestState] Add validations for mock presence depending on state type by @tiurin in https://github.com/localstack/localstack/pull/13457
[SFN][TestState] Add test for invalid state machine definition in test state call by @tiurin in https://github.com/localstack/localstack/pull/13446
mypy: add moto-ext as additional-dependencies in pre-commit hook by @bentsku in https://github.com/localstack/localstack/pull/13465
Lambda: Keep track of scaling config in store by @anisaoshafi in https://github.com/localstack/localstack/pull/13463
SFN:TestState: Add validations for mock fields compatibility by @tiurin in https://github.com/localstack/localstack/pull/13468
Fix use of json module as type hint by @giograno in https://github.com/localstack/localstack/pull/13372
Expand on the typing for volume types to support Kubernetes by @simonrw in https://github.com/localstack/localstack/pull/13467
CFn: handle updates with empty resource properties by @simonrw in https://github.com/localstack/localstack/pull/13471
Allow redirecting test traffic to arbitrary endpoint by @dfangl in https://github.com/localstack/localstack/pull/13472
Skip flaky Lambda streaming test by @joe4dev in https://github.com/localstack/localstack/pull/13486
ES/OpenSearch: fix concurrent startups on fresh install by @bentsku in https://github.com/localstack/localstack/pull/13481
ACM: Fix filtering by key type and support additional key types by @jtschladen in https://github.com/localstack/localstack/pull/13462
CFn: remove assertion on CFN_NO_WAIT_ITERATIONS by @simonrw in https://github.com/localstack/localstack/pull/13487
Add telemetry for Lambda Managed Instances by @joe4dev in https://github.com/localstack/localstack/pull/13466
CFnV2: Add support for ListAWS::EC2::SubnetId parameter by @pinzon in https://github.com/localstack/localstack/pull/13473
upgrade aws-sam-translator by @bentsku in https://github.com/localstack/localstack/pull/13490
ESM: add '$LATEST.PUBLISHED' support for Lambda Managed Instances by @anisaoshafi in https://github.com/localstack/localstack/pull/13493
IaC: Enable parity metrics to be captured during release by @k-a-il in https://github.com/localstack/localstack/pull/13494
SFN:TestState: Fix hardcoded region in test state's context object test by @tiurin in https://github.com/localstack/localstack/pull/13489
SFN:TestState: Add mock result validations for Map state by @tiurin in https://github.com/localstack/localstack/pull/13492
Skip failing DNS unit test by @joe4dev in https://github.com/localstack/localstack/pull/13501

localstack

v4.12.0

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What's Changed

Exciting New Features 🎉

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