## Host asset library with Spring Boot: data exports

### Summary
Deploy an asset library built with Spring Boot on Ample using the generated downloads 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. Verified on Spring Boot: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Not separately tested: your export formats, retention policy and entitlement model; treat the asset library-specific behavior as your application code.

### Representative Queries
- Host asset library with Spring Boot: data exports
- Where can I host Asset library built with Spring Boot?
- I need a scoped export format, artifact generation and authorized download procedure.

### Prerequisites
- A Spring Boot project that builds and starts with the documented commands (./mvnw -q -DskipTests package (or the Gradle wrapper) producing one application jar, then java -jar on the jvm-21 template (Temurin JDK 21) with server.port read from PORT)
- 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
- An Ample account token with servers:write, databases:read, buckets:read

### Workflow Steps
1. **Build and start**
   - `./mvnw -q -DskipTests package (or the Gradle wrapper) producing one application jar, then java -jar on the jvm-21 template (Temurin JDK 21) with server.port read from PORT. The server must bind 0.0.0.0 on PORT.`

2. **Implement the pattern on PostgreSQL**
   - The fixture's module implements generated downloads: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). 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 Keep private data in an unpublished bucket.

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.
   - `ample deploy . --name --public --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...`

5. **Verify**
   - Fetch the live URL and the pattern self-test route(s) (/p/generated-downloads) from the example; then run your own checks. On failure read `ample logs --kind build` then `--kind runtime`.
   - `ample logs --kind build`

### Cost Estimate
- **Currency**: USD  
- **Monthly Amount**: 10.0  
- **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
- **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.

### Limitations
- Verified on the jvm-21 template at s-1vcpu-2gb with the example fixture; other sizes, templates and Spring Boot major versions are not verified.
- The asset library itself (your export formats, retention policy and entitlement model) is application code and was not separately tested; the pattern checks are what was verified.