# Host Rest API with NestJS: Worker Execution and Job State

## Summary
Deploy a rest API built with NestJS as a public web service plus a dedicated worker process on Ample. `ample plan --write` discovers both services and their shared database and writes ample.toml; `ample up` reconciles the topology: a managed PostgreSQL 16 database, a public web microVM and a private worker microVM (kind worker, no public URL), both reading DATABASE_URL. Verified on NestJS: a separately deployed worker service (kind worker, no public URL) sharing a declared managed PostgreSQL database with the web service, consuming a jobs table with row locks and marking jobs done once (worker=done attempts=1). Not separately tested: your job payloads, retry policy and scheduling; treat the rest API-specific behavior as your application code.

## Representative Queries
- Host rest api with NestJS: worker execution and job state
- Where can I host REST API built with NestJS?
- I need a separately runnable worker, durable job records and idempotent retries; not a managed queue.

## Resource Requirements
- primitive:compute
- primitive:postgres

## Infrastructure Requirements
- **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
- **Postgres**: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

## Framework
NestJS

## Workload
REST API

## Release Status
published

## Support Status
verified

## Execution Status
ready

## Prerequisites
1. A repository with the web app and the worker as separate service directories (the fixture uses apps/web and apps/worker), each building and starting with the documented commands (npm install, nest build (TypeScript) then node dist/main.js on the node-22 template; the worker starts with node worker (its own package.json start script) and binds no port).
2. Both services read DATABASE_URL at runtime and share one jobs table; the worker claims rows with SELECT ... FOR UPDATE SKIP LOCKED and marks them done once.
3. An Ample account token with servers:write and databases:write (ample up creates the database).

## Workflow Steps
1. **Plan the topology**: Run the planner once. It discovers the web and worker services, infers kind = "worker" for the process without a port, declares the database each service needs, and writes ample.toml.
   Command: `ample plan --write .`
2. **Share one database**: Keep a single [databases.main] with engine = "postgres", drop any per-service database the planner added, and set DATABASE_URL = { database = "main" } under both [services.web.env] and [services.worker.env].
   Command: `ample plan --offline .`
3. **Apply**: Reconcile the whole manifest in dependency order: the database first, then both services. It is idempotent and never destructive.
   Command: `ample up .`
4. **Verify**: Fetch the web service URL and its worker status route (/p/worker-queue/status in the example).
   Command: `ample logs --kind runtime`

## Tested Configuration
- **Template**: node-22
- **Runtime**: node
- **Size**: s-1vcpu-1gb
- **Install**: npm install
- **Build**: npm run build --if-present
- **Start**: npm run start

## Examples
- **NestJS web + worker fixture**: A NestJS web app (apps/web) and a worker process (apps/worker) sharing one managed PostgreSQL database.

## Success Checks
- **Web Service**: Responds on its public URL
- **Worker**: Consumed the enqueued job

## Limitations
- Verified on the node-22 template at s-1vcpu-1gb for both services with the example fixture; other sizes, templates and NestJS major versions are not verified.
- The worker is a single long-running process supervised in its own microVM; there is no scheduler or horizontal worker scaling in this recipe.

## Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 15.0
- **Components**:
  - Web server: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
  - Worker server: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
  - Managed PostgreSQL database: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0

## Formats
- [HTML](/content/recipes/rest-api/nestjs/worker-state/index.html)
- [Markdown](/content/recipes/rest-api/nestjs/worker-state.md)
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