page:recipes:mobile backend:spring boot:response streaming

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.