### Host asset library with Flask: relational workflow state

#### Summary
Deploy a asset library built with Flask on Ample using the transactional workflows 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: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). Not separately tested: your domain records, validation rules and concurrency policy; treat the asset library-specific behavior as your application code.

#### Representative Queries
- Host asset library with Flask: relational workflow state
- Where can I host Asset library built with Flask?
- I need a domain record schema, validation rules and concurrency behavior.

#### Resource Requirements
- **Primitive:** Compute
- **Primitive:** Postgres

#### Framework
Flask

#### Workload
Asset library

#### Release Status
Published

#### Support Status
Verified

#### Execution Status
Ready

---

### Prerequisites
1. 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)
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

---

### Tested Configuration
- **Template:** python-3.12
- **Runtime:** python
- **Size:** s-1vcpu-1gb
- **Install:** python3 -m pip install --target .ample/python -r requirements.txt
- **Start:** PYTHONPATH=.ample/python:${PYTHONPATH:-} python3 app.py

---

### 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 transactional workflows: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). 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/transactional-workflows) from the example; then run your own checks. On failure read `ample logs  --kind build` then `--kind runtime`. `  
   Command: `ample logs  --kind build`

---

### 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 asset library itself (your domain records, validation rules and concurrency 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
- **Basis:** Size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty  
   - **Components:**
     - App server (size: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0)
     - Managed PostgreSQL database (size: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0)
  
### Evidence Summary
- **Kind:** canary_run  
   **Summary:** Flask pattern fixture deployed on Ample (pip install into .ample/python from requirements.txt, then waitress from app.py reading PORT on the python-3.12 template); checks passed for transactional-workflows and configuration-secrets. Pattern proof: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected).  
   **Observed At:** 2026-09-21T01:14:18Z
   **Expires At:** 2027-03-20T01:14:18Z

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### Next Actions
- **Action ID:** browse-catalog  
   **Label:** Browse the catalog index
- **Action ID:** search-recipes  
   **Label:** Search published recipes by intent, stack and constraints
- **Action ID:** plan:page:recipes:asset-library:flask:relational-workflow  
   **Label:** Prepare a side-effect-free deployment plan for an authorized project