AWS Adds Cluster Mode to Elastic Beanstalk

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Amazon Web Services (AWS) has introduced a new Cluster Mode feature to its Elastic Beanstalk platform, enabling applications to operate as containers within Amazon EKS clusters. This addition complements the existing EC2-based environment, now termed Beanstalk Standard, while maintaining consistent application, version, and environment principles.

Designed for teams managing multiple applications on shared resources, Cluster Mode supports deployment through source code, Dockerfiles, or container images stored in Amazon ECR. Source code is automatically built into container images using Cloud Native Buildpacks on AWS CodeBuild, within the customer’s AWS account.

Key Features

Cluster Mode utilizes nodes from EKS Auto Mode and employs OpenTelemetry for observability. Customers do not select clusters directly; instead, environments sharing the same VPC subnet set within an account are assigned to a common cluster. A new cluster is automatically created upon first use, typically within ten minutes, if a different subnet set is specified.

Direct cluster access is restricted, with management handled through the Elastic Beanstalk API, AWS CLI, or console. Paul Pollack, a software engineering manager at AWS, addressed concerns about vendor lock-in in his launch post, stating, “With Cluster Mode you can take over management of your application’s resources if you ever need to.”

Deployment and Isolation

Deployment options in Cluster Mode are more limited than initially indicated, primarily offering rolling updates or full replacements. Immutable deployments remain exclusive to Beanstalk Standard. By default, network traffic between environments on a shared cluster is blocked, with no option to disable this restriction.

Pricing and Availability

Cluster Mode’s cost structure is influenced by resource sharing. While Elastic Beanstalk does not charge a platform fee and computes costs align with EC2 rates, additional fees include a flat hourly EKS charge per cluster and an EKS Auto Mode management fee. Each load-balanced environment also incurs costs for its dedicated Application Load Balancer, and pod-level metrics are billed per resource, potentially increasing monitoring expenses compared to Standard.

Cost savings arise from shared nodes, though separate clusters are more expensive and less efficient in capacity utilization. Cluster Mode is available in all commercial AWS regions supporting Elastic Beanstalk and can be deployed via the console, AWS CLI, or CloudFormation, but it is not eligible for the AWS Free Tier.