## Host mobile backend with Spring Boot: worker execution and job state

### Summary
Deploy a mobile backend built with Spring Boot as a public web service plus a dedicated worker process on Ample. `ample plan --write` discovers both services and their shared database and writes ample.toml; `ample up` reconciles the topology: a managed PostgreSQL 16 database, a public web microVM and a private worker microVM (kind worker, no public URL), both reading DATABASE_URL. Verified on Spring Boot: a separately deployed worker service (kind worker, no public URL) sharing a declared managed PostgreSQL database with the web service, consuming a jobs table with row locks and marking jobs done once (worker=done attempts=1). Not separately tested: your job payloads, retry policy and scheduling; treat the mobile backend-specific behavior as your application code.

### Representative Queries
- Host mobile backend with Spring Boot: worker execution and job state
- Where can I host Mobile backend built with Spring Boot?
- I need a separately runnable worker, durable job records and idempotent retries; not a managed queue.

### Resource Requirements
- **Compute**
- **Postgres**

### Infra Requirements
1. **Compute**: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
2. **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.

### Framework
Spring Boot

### Workload
Mobile backend

### Release Status
Published

### Support Status
Verified

### Execution Status
Ready

### Prerequisites
- A repository with the web app and the worker as separate service directories (the fixture uses apps/web and apps/worker), each building and starting with the documented commands.
- Both services read DATABASE_URL at runtime and share one jobs table.
- An Ample account token with servers:write and databases:write.

### Workflow Steps
1. **Plan the topology**
   - Run the planner once. It discovers the web and worker services, infers kind = "worker" for the process without a port, declares the database each service needs, and writes ample.toml.
   - **Command**: `ample plan --write .`

2. **Share one database**
   - Keep a single [databases.main] with engine = "postgres", drop any per-service database the planner added, and set DATABASE_URL = { database = "main" } under both [services.web.env] and [services.worker.env].
   - **Command**: `ample plan --offline .`

3. **Apply**
   - Reconcile the whole manifest in dependency order: the database first, then both services. It is idempotent and never destructive.
   - **Command**: `ample up .`

4. **Verify**
   - Fetch the web service URL and its worker status route and confirm the worker processed the enqueued job.
   - **Command**: `ample logs --kind runtime`

### Examples
- **Spring Boot web + worker fixture**: A Spring Boot web app and a worker process sharing one managed PostgreSQL database; the queue module is under tests/deploy-canaries/_pattern-modules.

### Success Checks
1. Web service responds on its public URL.
   - **Kind**: http_get
   - **Path**: /
   - **Expect**: ample canary spring boot patterns

2. Worker consumed the enqueued job.
   - **Kind**: http_get
   - **Path**: /p/worker-queue/status
   - **Expect**: worker=done attempts=1 result=processed-by-worker

### Limitations
- Verified on the jvm-21 template at s-1vcpu-2gb for both services with the example fixture; other sizes, templates and Spring Boot major versions are not verified.
- The mobile backend itself was not separately tested; the worker-queue check is what was verified.

### Cost Estimate
- **Currency**: USD  
- **Monthly Amount**: 15.0  
- **Note**: Always-on monthly price of the tested sizes for the web service, the worker service and the database; apps auto-pause when idle.