elastic-beanstalk

What this skill does

# Elastic Beanstalk

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

## 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 (event-driven, scale-to-zero)
- 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.

## Workflow

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](references/platforms.md))
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](https://docs.aws.amazon.com/cli/latest/reference/elasticbeanstalk/)
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](../deploy/references/security.md)
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 +