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

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

## Resource Requirements
- Compute
- 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`

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

## Limitations
- Verified on the node-22 template at s-1vcpu-1gb for both services with the example fixture; other sizes, templates and Fastify 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.

## Evidence Summary
- Fastify web service plus a separate Fastify 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).

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