Elastic Beanstalk now runs on EKS

Cluster Mode is a second way to run an app on Elastic Beanstalk. Instead of one EC2 environment per application, your app runs as a pod on a shared EKS cluster that Beanstalk creates and owns. Hand it source code and buildpacks build the image in CodeBuild. No Dockerfile.

I have a rule for AWS services: build on the primitives, not on the convenience layers around them. Beanstalk has always been a convenience layer. I expected to write this one off too.

So I deployed the same small Node.js app twice. Once on Cluster Mode, once on a classic Standard Mode environment on a $2/month spot instance. Then I pushed a broken version to both: same app, listening on the wrong port.

Standard Mode reported Environment update completed successfully. Health stayed Green. The endpoint answered 502 Bad Gateway.

Cluster Mode did something else entirely.

That's the part that went right. The rest: option namespaces nobody had documented, an IAM role whose trust policy everyone guesses wrong, no Spot, and a control plane that bills $73 a month before the first request. And a few hours after one failed run, AWS Support opened a case on my account that I never asked for.