### Host ai chat application with Flask: streamed responses

Deploy a ai chat application 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 ai chat application-specific behavior as your application code.

#### Representative Queries
- Host ai chat application with Flask: streamed responses
- Where can I host AI chat application built with Flask?
- I need a tested end-to-end streaming transport, timeout behavior and client disconnect handling.

#### Resource Requirements
- `primitive:compute`
- `primitive: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
Flask

#### Workload
AI chat application

#### 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

#### Input Schema
- **type**: object  
  - **properties**:  
    - **env**:  
      - **type**: array  
      - **items**:  
        - **type**: string
    - **name**:  
      - **type**: string  
      - **maxLength**: 63  
      - **minLength**: 1
    - **path**:  
      - **type**: string  
      - **maxLength**: 512  
      - **minLength**: 1
    - **release_command**:  
      - **type**: string  
      - **maxLength**: 512
    - **start**:  
      - **type**: string  
      - **maxLength**: 512

#### 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

#### Examples
- **Title**: Flask pattern fixture  
  **Description**: Multi-pattern Flask app whose streaming response service module was checked live; the module is under tests/deploy-canaries/_pattern-modules.  
  **Source Reference**: tests/deploy-canaries/flask-patterns

#### Success Checks
1. **Description**: app responds on its public URL  
   **Kind**: http_get  
   **Path**: /  
   **Expect**: ample canary flask patterns
2. **Description**: 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 ai chat application 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
- **Currency**: USD  
- **Monthly Amount**: 10.0  
- **Authoritative**: true  
- **Basis**: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
- **Components**: 
  - **Name**: app server  
    - **Size**: s-1vcpu-1gb  
    - **Quantity**: 1.0  
    - **Monthly Amount**: 5.0  
  - **Name**: 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. Buckets are allocation-priced per quota and not included.

#### 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 streaming-response-service and configuration-secrets. Pattern proof: 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).  
  **Observed At**: 2026-09-21T01:14:18Z
  **Implementation Revision**: 50dbac567d2c5cc8e55e6c748a646be0025d9cfb-dirty (CLI 0.1.21)
  **Expires At**: 2027-03-20T01:14:18Z
  **Scope**:  
    - **Checks**: [/p/streaming-response-service]
    - **Pattern**: pattern:streaming-response-service
    - **Template**: python-3.12

- **Kind**: canary_run  
  **Summary**: The same Flask app deployed with a --release-command migration; the marker it created was readable after activation.
  **Observed At**: 2026-09-20T01:54:51Z
  **Implementation Revision**: 199ff1dfd52683832ae75d3f98b53a7a4bff7f96-dirty (CLI e3181f5)
  **Expires At**: 2027-03-19T01:54:51Z
  **Scope**:  
    - **Pattern**: pattern:streaming-response-service

#### Last Verified At
2026-09-21T01:14:18Z

#### Unknowns
- region availability is unknown until a verified region fact is recorded
- compliance attestations are unknown; none are claimed

#### Links
- **HTML**: https://ample.computer/recipes/ai-chat-application/flask/response-streaming
- **Markdown**: https://ample.computer/recipes/ai-chat-application/flask/response-streaming.md
- **JSON**: https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Aai-chat-application%3Aflask%3Aresponse-streaming