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

## Summary
Deploy a knowledge base built with Phoenix 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 Phoenix: 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 Phoenix: object-stored public media
- Where can I host Knowledge base built with Phoenix?
- 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
- **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
- **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
- **Status**: verified  
- **Summary**: Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

### 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.

## Workflow Steps
1. **Build and start**  
   - mix deps.get, MIX_ENV=prod mix compile and mix release in the builder, then the release bin script with PHX_SERVER=true on the elixir-1.18 template; PORT, DATABASE_URL and SECRET_KEY_BASE read in config/runtime.exs. 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.  
   - Command: ample deploy . --name  --public --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=... --env CDN_PUBLIC_URL=...

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`.  
   - Command: ample logs --kind build

## Success Checks
- App responds on its public URL (http_get path: / expect: ample canary phoenix patterns)
- Public-media-library self-test (http_get path: /p/public-media-library expect: a CDN URL whose content is served publicly)

## Limitations
- Verified on the elixir-1.18 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Phoenix 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.
- 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.
- PutObject and GetObject with path-style addressing are verified; multipart upload, listing, presigned URLs and lifecycle rules are not.
- The CDN serves published-bucket objects only; cache rules, purge and TTL control are not verified (the fixture sets Cache-Control on upload and versions keys).

## 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  
- **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.