# Host public directory with Flask: object-stored public media

Deploy a public directory 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 public directory-specific behavior as your application code.

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

## Resource Requirements
- primitive:compute
- primitive:postgres
- primitive:s3-compatible-object-storage
- primitive:cdn

## Infrastructure Requirements
### Compute
- **Label:** 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.
  
### Postgres
- **Label:** 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.
  
### S3-Compatible Object Storage
- **Label:** 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.
  
### CDN
- **Label:** 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
### 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.
### 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.
### 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.
### 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.
  
    ```sh
    ample deploy . --name  --public --start "python3 app.py" --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=... --env CDN_PUBLIC_URL=...
    ```
### 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`.
  
    ```sh
    ample logs  --kind build
    ```

## Examples
### Flask pattern fixture
- **Description:** Multi-pattern Flask app whose public media library module was checked live; the module is under tests/deploy-canaries/_pattern-modules.
  
### Success Checks
- App responds on its public URL
- Public-media-library self-test

## 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 public directory 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
- **Basis:** Size prices from pricing.toml (loaded by the API) at build revision ...
  
### Components
- App server - Size: s-1vcpu-1gb, Quantity: 1.0, Monthly Amount: 5.0
- Managed PostgreSQL database - Size: s-1vcpu-1gb, Quantity: 1.0, Monthly Amount: 5.0

## Evidence Summary
- Canary run: Flask pattern fixture deployed on Ample; checks passed for public-media-library and configuration-secrets. Pattern proof: an object written to a published bucket with an immutable Cache-Control header, a mapping row, and the CDN URL serving it publicly.

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