# Host Knowledge Base with Flask: Object-Stored Public Media

### Summary
Deploy a knowledge base built with Flask on Ample using the public media library 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, a private S3-compatible bucket holds objects with credentials delivered as encrypted environment variables, and a published bucket serves public assets from the CDN host. Verified on Flask: an object written to a published bucket with an immutable Cache-Control header, a mapping row, and the CDN URL serving it publicly. Not separately tested: your media processing, object layout, and cache policy; treat the knowledge base-specific behavior as your application code.

### Representative Queries
- Host knowledge base with Flask: object-stored public media
- Where can I host Knowledge base built with Flask?
- I need an object layout, public asset URL policy, and CDN delivery configuration.

### Framework
Flask

### Workload
Knowledge base

### Release Status
Published

### Support Status
Verified

### Execution Status
Ready

### Resource Requirements
- Compute
- Postgres
- S3-compatible object storage
- CDN

### Infrastructure Requirements
1. **Compute**  
   **Status**: Verified  
   **Summary**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
2. **Postgres**  
   **Status**: Verified  
   **Summary**: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.
3. **S3-compatible object storage**  
   **Status**: Verified  
   **Summary**: Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.
4. **CDN**  
   **Status**: Verified  
   **Summary**: The CDN host serves objects from published buckets. It does not front app compute and is not a cache or key-value store.

### 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)
- A bucket from `ample bucket create` with its credentials passed as encrypted S3_* environment variables and a second, published bucket for public assets (CDN_*)
- An Ample account token with servers:write, databases:read, buckets:read

### 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 public media library: an object written to a published bucket with an immutable Cache-Control header, a mapping row, and the CDN URL serving it publicly. Copy the approach into your schema; keep migrations idempotent and run them with --release-command.
3. **Wire object storage**  
   Create the bucket(s), then pass endpoint, region, bucket, and keys as --env values. Use path-style addressing. Keep private data in an unpublished bucket. Publish only the bucket that serves public assets and reference its CDN URL.
4. **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.
5. **Verify**  
   Fetch the live URL and the pattern self-test route(s) (/p/public-media-library) from the example; then run your own checks. On failure read `ample logs  --kind build` then `--kind runtime`.

### 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 knowledge base itself (your media processing, object layout, and cache 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: s-1vcpu-1gb, Quantity: 1.0, Monthly Amount: 5.0  
  - Managed PostgreSQL database: s-1vcpu-1gb, Quantity: 1.0, Monthly Amount: 5.0

### Evidence Summary
- **Canary Run**:  
   - Summary: Flask pattern fixture deployed on Ample; checks passed for public-media-library and configuration-secrets. 
   - Observed At: 2026-09-21T01:14:18Z  
   - Expires At: 2027-03-20T01:14:18Z

### Formats
- [HTML Format](/content/recipes/knowledge-base/flask/public-media/index.html)  
- [Markdown Format](/content/recipes/knowledge-base/flask/public-media.md)  
- [JSON Format](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Aknowledge-base%3Aflask%3Apublic-media)