## Host mcp server with Express: Postgres-backed state

Deploy a mcp server built with Express on Ample using the durable job state pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, a managed PostgreSQL 16 database is auto-provisioned and injected as DATABASE_URL. Verified on Express: a jobs table with a state and attempts counter, processing inside a row-locked transaction, and a second run that is a no-op (job=done attempts=1 idempotent=true). Not separately tested: your job types, payload schema and retry policy; treat the mcp server-specific behavior as your application code.

### Resources Requirements
- Compute
- 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: Express
### Workload: MCP server

### Prerequisites
- A Express project that builds and starts with the documented commands (npm install, npm run build --if-present, npm run start on the node-22 template)
- A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env)
- An Ample account token with servers:write, databases:read

### Workflow Steps
1. **Build and start**: `npm install, npm run build --if-present, npm run start` on the node-22 template. The server must bind 0.0.0.0 on PORT.
2. **Implement the pattern on PostgreSQL**: The fixture's module implements durable job state: a jobs table with a state and attempts counter, processing inside a row-locked transaction, and a second run that is a no-op (job=done attempts=1 idempotent=true). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.
3. **Deploy**: Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked). Re-running with no change is a no-op. Command: `ample deploy . --name --public`
4. **Verify**: Fetch the live URL and the pattern self-test route(s) (/p/durable-job-state) from the example; then run your own checks. On failure read `ample logs --kind build` then `--kind runtime`. Command: `ample logs --kind build`

### Success Checks
- App responds on its public URL (HTTP GET /) expect: `ample canary express patterns`
- Durable-job-state self-test (HTTP GET /p/durable-job-state) expect: `job=done attempts=1 idempotent=true`

### Limitations
- Verified on the node-22 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Express major versions are not verified. 
- The mcp server itself (your job types, payload schema and retry policy) is application code and was not separately tested; the pattern checks are what was verified.

### Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Basis**: Size prices from pricing.toml at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
- **Note**: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle. Buckets are allocation-priced per quota and not included.

### Evidence Summary
- **Canary run**: Express pattern fixture deployed on Ample; checks passed for durable-job-state and configuration-secrets.

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