## Host subscription content with Spring Boot: relational catalog data

### Summary

Deploy a subscription content built with Spring Boot on Ample using the transactional workflows 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 Spring Boot: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). Not separately tested: your domain records, validation rules and concurrency policy; treat the subscription content-specific behavior as your application code.

### Infrastructure requirements

- **Compute**: verified (Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.)
- **Postgres**: verified (Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.)

### 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`).
- An Ample account token with `servers:write`, `databases:read`.

### Exact tested configuration

- **template**: `jvm-21`
- **runtime**: `java`
- **size**: `s-1vcpu-2gb`
- **build**: `./mvnw -q -DskipTests package`
- **start**: `java -jar $(ls target/*.jar | grep -v -- '-plain' | head -n 1)`

### 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 transactional workflows: an optimistic version check and an event row written in the same transaction, a stale update rejected, and a history query over the application-owned events (history=2 conflict=rejected). 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).
   ```
   ample deploy . --name <app-name> --public
   ```
4. **Verify.** Fetch the live URL and the pattern self-test route(s) (`/p/transactional-workflows`) from the example; then run your own checks. On failure read `ample logs <deployment_id> --kind build` then `--kind runtime`.
   ```
   ample logs <deployment_id> --kind build
   ```

### Tested examples

- **Spring Boot pattern fixture** (tests/deploy-canaries/spring-boot-patterns): Multi-pattern Spring Boot app whose transactional workflows module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

### Success checks

- app responds on its public URL (`/` on the live URL, expect ample canary spring boot patterns)
- transactional-workflows self-test (`/p/transactional-workflows` on the live URL, expect `tx=ok history=2 conflict=rejected`)

### 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 subscription content itself (your domain records, validation rules and concurrency 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.

### Cost estimate

Estimated 10.00 USD per month.
- app server x1 `s-1vcpu-1gb`: 5.00 USD
- managed PostgreSQL database x1 `s-1vcpu-1gb`: 5.00 USD

### Verification evidence

- canary_run on 2026-09-21 at revision `1d28ae0-dirty (CLI 0.1.21)`: Spring Boot pattern fixture deployed on Ample; checks passed for transactional-workflows and configuration-secrets.
- canary_run on 2026-09-20 at revision `af6f45adea26-dirty (CLI af6f45a)`: The same Spring Boot app deployed with a `--release-command` migration; the marker it created was readable after activation.

### Last verified

2026-09-21

### Execution binding

MCP tool `ample_deploy`, binding state `current`, required scopes: `servers:write`, `databases:read`.