# Host mcp server with Express: worker execution and job state

Deploy a mcp server built with Express 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 Express: 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 mcp server-specific behavior as your application code.

## Representative Queries
- Host mcp server with Express: worker execution and job state
- Where can I host MCP server built with Express?
- I need a separately runnable worker, durable job records and idempotent retries; not a managed queue.

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

## Infrastructure Requirements
1. **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
2. **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.

## Prerequisites
- 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, npm run build --if-present, npm run start on the node-22 template; the worker starts with node worker (its own package.json start script) and binds no port)
- 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.
- 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. Exit 2 means it left questions in the manifest; answer them with --answer or by editing the file. 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; exit 0 means everything applied, 2 needs input, 1 a failed resource (independent siblings still proceed and re-running resumes). Command: `ample up .`
4. **Verify**: Fetch the web service URL and its worker status route (/p/worker-queue/status in the example) and confirm the worker processed the enqueued job; on failure read the worker service's runtime logs. Command: `ample logs  --kind runtime`

## Examples
- **Express web + worker fixture**: A Express web app (apps/web) and a worker process (apps/worker) sharing one managed PostgreSQL database; the queue module is under tests/deploy-canaries/_pattern-modules.

## Success Checks
1. **Web service responds** on its public URL
   - Kind: http_get
   - Path: /
   - Expect: ample canary express patterns
2. **Worker consumed** the enqueued job
   - Kind: http_get
   - Path: /p/worker-queue/status
   - Expect: worker=done attempts=1 result=processed-by-worker

## Limitations
- Verified on the node-22 template at s-1vcpu-1gb for both services with the example fixture; other sizes, templates and Express major versions are not verified.
- The mcp server itself (your job payloads, retry policy and scheduling) is application code and was not separately tested; the worker-queue check is what was verified.
- The worker is a single long-running process supervised in its own microVM; there is no scheduler, cron or horizontal worker scaling in this recipe, and the check ran immediately after deploy so idle behavior of the worker VM is not verified.
- The worker service is private: it has no public URL and is reached only through the shared database; both services are placed with their database.
- Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.
- Region, compliance attestations and request-duration limits are unknown and not claimed.

## Cost Estimate
- **Monthly Amount**: $15.00
- **Components**:
  - **Web server**: size s-1vcpu-1gb, quantity 1.0, monthly amount $5.00
  - **Worker server**: size s-1vcpu-1gb, quantity 1.0, monthly amount $5.00
  - **Managed PostgreSQL database**: size s-1vcpu-1gb, quantity 1.0, monthly amount $5.00
- Note: Always-on monthly price of the tested sizes for the web service, the worker service and the database; apps auto-pause when idle.

## Evidence Summary
- **Canary run**: Express web service plus a separate Express worker process deployed on Ample with `ample plan --write` then `ample up` (npm install, npm run build --if-present, npm run start on the node-22 template); the web service enqueued a job that the private worker service consumed from the shared managed PostgreSQL database. Pattern proof: 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).

**Last Verified At**: 2026-09-20T03:56:46Z

## MCP Binding
- **Registry Reference**: mcp:ample_up
- **Tool Name**: ample_up
- **Binding State**: current

## Unknowns
- Region availability is unknown until a verified region fact is recorded
- Compliance attestations are unknown; none are claimed.

## Formats
- **HTML**: [Ample Recipe](/content/recipes/mcp-server/express/worker-state/index.html)
- **Markdown**: [Ample Recipe (Markdown)](/content/recipes/mcp-server/express/worker-state.md)
- **JSON**: [Ample Recipe (JSON)](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Amcp-server%3Aexpress%3Aworker-state)

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