elastic-beanstalk

Elastic Beanstalk

Deploy applications to production on AWS with full lifecycle management. Elastic Beanstalk is an application management service: the user provides application code or a container image, AWS manages everything underneath (deployment, scaling, patching, monitoring, health response).

There are two modes, and the choice determines every setting that follows. Standard runs the application on Amazon EC2; Cluster runs a container on a managed Amazon EKS Auto Mode cluster. See Choose the Mode.

When to Use

Elastic Beanstalk is the right choice when:

• User explicitly asks for Elastic Beanstalk, EB, or a managed application platform
• User says "don't want to manage servers", "managed patching", or "Heroku-like"
• User is migrating from Heroku, Render, or Railway
• User wants AWS to manage ongoing operational lifecycle (patching, scaling, health monitoring, rollback, deployments) after initial setup
• App is a web framework, API, or background worker on a standard runtime and the user signals low infrastructure involvement

Elastic Beanstalk is NOT the right choice when:

• User explicitly wants serverless/Lambda — this imposes a different programming model (event-driven functions, stateless, cold starts, 15-min max execution) rather than just eliminating server management
• User wants fine-grained container orchestration control (use ECS)
• User already has Kubernetes expertise and wants direct K8s access (use EKS)
• App is a static site or SPA (use Amplify Hosting for the frontend; deploy the backend API separately if present)
• User already has ECS task definitions or Fargate configuration

Key Distinction

ECS and EKS are infrastructure management services: the user defines and operates the deployment infrastructure (task definitions, services, clusters, scaling policies) and owns ongoing operational decisions. Elastic Beanstalk is an application management service: the user provides source code or a Docker image, and AWS provisions and operates the production environment on an ongoing basis. The result is the same reliability, but with lower ongoing maintenance cost because operational responsibility stays with the provider.

Both models support IaC (CDK, CloudFormation, Terraform). The distinction is not about tooling — it is about who manages the lifecycle after deployment.

Lambda/serverless is a different axis entirely. "Don't want to manage servers" does not mean "wants serverless" — Elastic Beanstalk also eliminates server management while preserving the standard application programming model (long-running processes, persistent connections, threads, and — in Standard mode only — local state; Cluster mode replicas have ephemeral local storage). Serverless imposes a specific programming model: stateless functions, cold starts, event-driven invocation, and a 15-minute execution ceiling. Route to Lambda only when the user explicitly asks for serverless or the workload is natively event-driven (e.g., S3 triggers, API Gateway request/response with no session state).

Choose the Mode

Decide before generating anything. The modes share an API and nothing else: a Standard mode namespace passed to a Cluster mode environment is rejected, not ignored.

Cluster mode has an entry requirement, and it is checked first. Route to Cluster only when every service can run as identical, interchangeable replicas and all durable state — uploads, sessions, caches, working files — already lives outside the container. Replica local storage is ephemeral and is lost on every restart, and there is no persistent volume option. An application that fails this goes to Standard mode, or gets changed first; a multi-service signal does not override it. See the application contract.

Then the signals:

Signal	Mode
Source on a standard runtime; Windows or .NET Framework	Standard
Worker consuming an SQS queue	Standard
Writes uploads, sessions, or working files to local disk	Standard
One small application, cost is the priority	Standard
Several services needing private service-to-service traffic	Cluster
Kubernetes underneath without operating Kubernetes	Cluster
Managed OpenTelemetry, or faster deploys and scaling	Cluster

A container image alone does not settle it, because Standard mode has a Docker platform too — ask. Prefer Cluster mode when the application is containerised, multi-service, and meets the contract above, since environments sharing subnets share one cluster and reach each other privately. Prefer Standard for a single container where a cluster is not yet justified. Do not propose migrating a working Standard environment unless asked: there is no in-place conversion, only new environments and a CNAME swap.

If the mode is Cluster, follow cluster mode and stop here. Everything below is Beanstalk Standard.

Workflow (Standard)

This skill is invoked after the deploy skill selects Elastic Beanstalk as the deployment target. The deploy skill handles codebase analysis and cost estimation. This skill handles EB-specific configuration:

1. Map to platform - Select the EB platform branch (see platforms)
2. Configure - Environment type (web server or worker), instance size, scaling
3. Generate - AWS CLI commands, CDK, or Terraform (see IaC section below)
4. Deploy - Execute with user confirmation

Defaults

Setting	Dev	Production
Environment type (web)	Load-balanced (min=1, max=1)	Load-balanced, Multi-AZ
Environment type (worker)	Auto Scaling group (min=1, max=1)	Auto Scaling group (min=2, max=4)
Instance	t3.small	t3.medium or larger
Deployments	All-at-once	Rolling with additional batch
Health reporting	Enhanced	Enhanced
Managed updates	Enabled (weekly)	Enabled (maintenance window)
HTTPS (web only)	ACM certificate + ALB	ACM certificate + ALB

Default to dev unless user says "production" or "prod".

Always use load-balanced environments for web server types. This ensures instances stay in private subnets behind an ALB, HTTPS terminates via ACM automatically, and scaling up later is a config change rather than an environment type migration. Dev deployments with min=max=1 cause brief downtime on deploy (single instance, all-at-once). If zero-downtime dev is needed, use min=1 max=2 with rolling.

Worker environments do not have load balancers — they receive work from SQS and are scaled via Auto Scaling group settings.

Environment Types

Signal in Codebase	Environment Type
HTTP listener, web framework, API routes	Web server
Queue-based consumer, SQS processing, no HTTP serving	Worker
HTTP serving + queue-based background processing	Web server + separate Worker environment

Worker environments receive work via an SQS queue managed by Elastic Beanstalk. EB's SQS daemon sends HTTP POST requests to the application at a configurable path (default: POST /). The application must expose this HTTP endpoint to process each message — no SQS SDK integration required.

Worker environments also support periodic tasks via cron.yaml for scheduled jobs (alternative to EventBridge + Lambda when the user is already using EB).

If the app uses in-process background threads or async tasks (not queue-based), a single web server environment is sufficient — do not create a separate Worker.

IaC Generation

Default: AWS CLI — no extra tooling to install. The agent orchestrates the multi-step workflow:

1. aws elasticbeanstalk create-storage-location → returns the S3 bucket (idempotent — returns existing bucket if already created)
2. aws elasticbeanstalk create-application
3. Zip source bundle, upload to the bucket from step 1
4. aws elasticbeanstalk create-application-version
5. aws elasticbeanstalk create-environment with --option-settings (web: --tier Name=WebServer,Type=Standard, worker: --tier Name=Worker,Type=SQS/HTTP)
6. aws elasticbeanstalk wait environment-updated
7. Subsequent deploys: new version + update-environment

Resolve the --solution-stack-name by running aws elasticbeanstalk list-available-solution-stacks and filtering for the detected platform (e.g., ".NET" + "Amazon Linux 2023"). Alternatively, use --platform-arn from aws elasticbeanstalk list-platform-versions.

Use .ebextensions/ and platform hooks for customization.

See AWS CLI EB reference for full command documentation.

Override: CDK (TypeScript) when the user has an existing CDK project, wants repeatable IaC, or explicitly requests it:

• CfnApplication, CfnEnvironment, CfnConfigurationTemplate

Override: Terraform when the user's repo already has Terraform:

• aws_elastic_beanstalk_application, aws_elastic_beanstalk_environment

CDK and Terraform templates are scannable by cfn-nag/checkov pre-deploy.

Security

Apply these automatically:

• Web server instances in private subnets behind ALB
• Worker instances in private subnets with NAT Gateway for outbound
• HTTPS via ACM certificate on ALB (web server environments)
• IAM instance profile with least-privilege permissions — scan source code for AWS SDK client usage to determine required actions (e.g., AmazonBedrockRuntimeClient → bedrock:InvokeModel, AmazonS3Client → s3:GetObject/s3:PutObject on specific buckets)
• Enhanced health reporting enabled
• Managed platform updates enabled
• Security groups: ALB accepts 443, instances accept only from ALB

See the deploy skill's security defaults for encryption, VPC placement, and IAM patterns.

Cost

Elastic Beanstalk has no service fee. Cost = underlying AWS resources. Query the awspricing MCP server for region-accurate estimates. Approximate us-east-1 pricing:

Configuration	Estimated Monthly Cost
Dev web (1x t3.small + ALB)	~$35-40
Dev worker (1x t3.small, no ALB)	~$15-20
Production web (4x t3.medium + ALB, Multi-AZ)	~$150-200

Add RDS/Aurora costs separately if database is included.

References

• Beanstalk Cluster mode — containers on managed EKS
• Supported platforms and detection — Standard mode
• Configuration and customization — Standard mode