# Host mobile backend with Fastify: Postgres-backed state

Deploy a mobile backend built with Fastify 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 Fastify: 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 mobile backend-specific behavior as your application code.

## Summary
- **Framework:** Fastify
- **Workload:** Mobile backend
- **Release Status:** published
- **Support Status:** verified
- **Execution Status:** ready
  
## Prerequisites
1. A Fastify project that builds and starts with the documented commands (npm install, npm run build --if-present, npm run start on the node-22 template)
2. A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env)
3. An Ample account token with servers:write, databases:read

## Resource Requirements
- **Compute**
- **Postgres**

## 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`

## Examples
- **Title:** Fastify pattern fixture
  - **Description:** Multi-pattern Fastify app whose durable job state module was checked live; the module is under tests/deploy-canaries/_pattern-modules.
  - **Source Reference:** tests/deploy-canaries/fastify-patterns

## Success Checks
1. **App responds on its public URL**: `http_get`, path: `/`, expect: `ample canary fastify patterns`
2. **Durable-job-state self-test**: `http_get`, path: `/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 Fastify major versions are not verified.
- The mobile backend 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
- **Components:**
  - App server: size s-1vcpu-1gb, quantity 1.0, monthly amount 5.0
  - Managed PostgreSQL database: size s-1vcpu-1gb, quantity 1.0, monthly amount 5.0
- **Note:** Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.

## Next Actions
- [Browse the catalog index](./catalog/index)
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- [Prepare a side-effect-free deployment plan for an authorized project](./plan)