### Host REST API with Flask: Streamed Responses

**Summary**  
Deploy a REST API built with Flask on Ample using the streaming response service 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 Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=true). Not separately tested: your event schema, reconnection strategy and any per-request duration ceiling beyond the 70 seconds measured; treat the REST API-specific behavior as your application code.

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### 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 streaming response service: a Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=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/streaming-response-service) 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  
  - Kind: `http_get`  
  - Path: `/`  
  - Expect: `ample canary flask patterns`  
- Streaming-response-service self-test  
  - Kind: `http_get`  
  - Path: `/p/streaming-response-service`  
  - Expect: `an SSE stream: data: id=, then chunk events one interval apart (read incrementally: first chunk within seconds, chunks spread over the interval), then data: done; /status?id= reports sent=N disconnected=true|false done=true|false`

### 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 REST API itself (your event schema, reconnection strategy, and any per-request duration ceiling beyond the 70 seconds measured) 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  
- Monthly Amount: **$10.00**  
- Components:  
  - App server (s-1vcpu-1gb): $5.00  
  - Managed PostgreSQL database (s-1vcpu-1gb): $5.00  
- Note: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.

### Evidence Summary  
- **Canary Run**: Flask pattern fixture deployed on Ample; checks passed for streaming-response-service and configuration-secrets.
  - **Summary**: A Server-Sent Events endpoint read incrementally through the public HTTPS gateway.
  - **Observed At**: `2026-09-21T01:14:18Z`
- **Canary Run**: The same Flask app deployed with a --release-command migration; the marker it created was readable after activation.
  - **Summary**: The marker it created was readable after activation.
  - **Observed At**: `2026-09-20T01:54:51Z`

### Next Actions  
- [Browse the catalog index](https://api.ample.computer/v1/catalog)  
- [Search published recipes](https://api.ample.computer/v1/catalog/search) by intent, stack, and constraints  
- [Prepare a side-effect-free deployment plan](https://api.ample.computer/v1/catalog/plan) for an authorized project  
- [Read the existing agent authentication setup](https://api.ample.computer/mcp/setup)  
- [Browse REST API](https://api.ample.com/computer/v1/catalog/nodes/workload%3Arest-api)  
- [Browse Flask](https://api.ample.com/computer/v1/catalog/nodes/stack%3Aframework-flask)  
- [Browse Streaming response service](https://api.ample.com/computer/v1/catalog/nodes/pattern%3Astreaming-response-service)  
- [Browse Deploy API](https://api.ample.com/computer/v1/catalog/nodes/intent%3Adeploy-api)