### Host mobile backend with Spring Boot: streamed responses

#### Summary
Deploy a mobile backend built with Spring Boot on Ample using the streaming response service 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: a Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=true). Not separately tested: your event schema, reconnection strategy and any per-request duration ceiling beyond the 70 seconds measured; treat the mobile backend-specific behavior as your application code.

#### Resource Requirements
- primitive:compute
- primitive:postgres

#### Infrastructure 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
- A Spring Boot project that builds and starts with the documented commands (./mvnw -q -DskipTests package) 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.

#### 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 streaming response service: a Server-Sent Events endpoint read incrementally through the public HTTPS gateway.
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). Command: `ample logs  --kind build` then `--kind runtime`.

#### Success Checks
- App responds on its public URL.
- Streaming-response-service self-test at `/p/streaming-response-service`.

#### Limitations
- Verified on the jvm-21 template at s-1vcpu-2gb with the example fixture; other sizes are not verified. 
- The mobile backend itself (your event schema) is application code and was not separately tested.

#### Cost Estimate
- **Monthly Amount**: $10.00
    - **app server**: s-1vcpu-1gb, quantity: 1, monthly: $5.00
    - **managed PostgreSQL database**: s-1vcpu-1gb, quantity: 1, monthly: $5.00
    - Note: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.

#### Examples
- Title: **Spring Boot pattern fixture**
  Description: Multi-pattern Spring Boot app whose streaming response service module was checked live.
  Source Ref: tests/deploy-canaries/spring-boot-patterns.

#### Evidence Summary
- **Canary Run**: Spring Boot pattern fixture deployed on Ample with checks passed for streaming-response-service.

#### Next Actions
- Browse the catalog index.
- Read the existing agent authentication setup.
- Prepare a side-effect-free deployment plan for an authorized project.