## Host mobile backend with Flask: Postgres-backed state

Deploy a mobile backend built with Flask 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 Flask: 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.

### Prerequisites
- A Flask project that builds and starts with the documented commands (pip install into .ample/python from requirements.txt, then waitress from app.py reading PORT on the python-3.12 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.

### Resource 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.

### Workflow Steps
1. **Build and start**:  pip install into .ample/python from requirements.txt, then waitress from app.py reading PORT on the python-3.12 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 --start "python3 app.py"`
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
- **Flask pattern fixture**: Multi-pattern Flask app whose durable job state module was checked live; the module is under tests/deploy-canaries/_pattern-modules. Source: `tests/deploy-canaries/flask-patterns`

### Success Checks
- App responds on its public URL.
- Durable-job-state self-test: fetch `/p/durable-job-state`.

### Limitations
- Verified on the python-3.12 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Flask 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.
- Region, compliance attestations and request-duration limits are unknown and not claimed.
- Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
- Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.

### Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Components**:
  - App server: s-1vcpu-1gb x 1 = 5.0
  - Managed PostgreSQL database: s-1vcpu-1gb x 1 = 5.0
- **Note**: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.

### Evidence Summary
- Canary run summary showing checks passed for durable-job-state and configuration-secrets.

### Next Actions
- Browse the catalog index:  `GET /v1/catalog`
- Search published recipes:  `POST /v1/catalog/search`
- Prepare a deployment plan:  `POST /v1/catalog/plan`
- Read existing authentication setup:  `GET /mcp/setup`
- Browse Mobile backend:  `GET /v1/catalog/nodes/workload%3Amobile-backend`
- Browse Flask:  `GET /v1/catalog/nodes/stack%3Aframework-flask`
- Browse Durable job state:  `GET /v1/catalog/nodes/pattern%3Adurable-job-state`
- Browse Deploy API:  `GET /v1/catalog/nodes/intent%3Adeploy-api`