### Host digital downloads with Spring Boot: relational catalog data

Deploy a digital downloads 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 digital downloads-specific behavior as your application code.

#### Representative Queries
- Host digital downloads with Spring Boot: relational catalog data
- Where can I host Digital downloads built with Spring Boot?
- I need catalog tables, transactional update logic and application-level access boundaries.

#### Resource Requirements
- **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
- **Postgres**: 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
1. 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).
2. A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env).
3. An Ample account token with servers:write, databases: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 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). Re-running with no change is a no-op.
   - Command: `ample deploy . --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  --kind build` then `--kind runtime`.
   - Command: `ample logs  --kind build`

#### 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 digital downloads 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
- **Currency**: USD
- **Monthly Amount**: 10.0
- **Basis**: Size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
- **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.

#### Success Checks
- App responds on its public URL: (kind: http_get, path: /, expect: ample canary spring boot patterns)
- Transactional-workflows self-test: (kind: http_get, path: /p/transactional-workflows, expect: tx=ok history=2 conflict=rejected)

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

#### Formats
- **HTML**: [Host digital downloads with Spring Boot](/content/recipes/digital-downloads/spring-boot/relational-catalog/index.html)
- **Markdown**: [Host digital downloads with Spring Boot](/content/recipes/digital-downloads/spring-boot/relational-catalog.md)
- **JSON**: [Host digital downloads with Spring Boot](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Adigital-downloads%3Aspring-boot%3Arelational-catalog)