The Buildkite elastic stack for AWS hasn’t seen a major release in a long time, and in the meantime our main branch has accumulated lots of changes and adjustments including (potentially) breaking changes we’ve been wanting to make for some time. We’re nearly ready to call it stable, but we just want to collect a bit more data about it in the wild, so today we’re releasing a new beta of the v5.0.0 version of the stack.
What’s new?
Previously experimental Lambda-based scaler is the new default 
Our previously experimental fast autoscaler that scales up much faster is now always used. Instances will automatically scale to demand using the stack defaults and you should see good results without changing any parameters.
Experimental Windows support is now available 
A new AMI built on Windows Server 2019 is optionally available to use in the stack for Windows builds. You can enable this by changing the InstanceOperatingSystem setting from the default linux to windows. We’ve observed issues with Windows instances when MinSize is set above 0, so please avoid that for now. Huge thanks to our GitHub contributors for this feature!
Download
Head to the GitHub pre-release here: https://github.com/buildkite/elastic-ci-stack-for-aws/releases/tag/v5.0.0-beta1 and either launch a new stack (recommended) or update an existing one (check our changelog for notes on parameter changes)
Feedback welcome!
Let us know in the comments here or over on the GitHub project if you have problems with it, and we’ll continue to monitor this thread and support this release.