Host mobile backend with Spring Boot: worker execution and job state | Ample
INFRASTRUCTURE
What it needs
- 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
Before you start
- 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 (./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 worker starts with java -jar of its own Maven module (plain JDBC) and binds no port)
- Both services read DATABASE_URL at runtime and share one jobs table; the worker claims rows with SELECT ... FOR UPDATE SKIP LOCKED and marks them done once
- An Ample account token with servers:write and databases:write (ample up creates the database)
TESTED CONFIGURATION
Exactly what was tested
- build:
./mvnw -q -DskipTests package - runtime:
java - size:
s-1vcpu-2gb - start:
java -jar $(ls target/*.jar | grep -v -- '-plain' | head -n 1) - template:
jvm-21
STEP BY STEP
How to do it
- 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. Exit 2 means it left questions in the manifest; answer them with --answer or by editing the file.
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].
ample plan --offline .
- 3
Apply
Reconcile the whole manifest in dependency order: the database first, then both services. It is idempotent and never destructive; exit 0 means everything applied, 2 needs input, 1 a failed resource (independent siblings still proceed and re-running resumes).
ample up .
- 4
Verify
Fetch the web service URL and its worker status route (/p/worker-queue/status in the example) and confirm the worker processed the enqueued job; on failure read the worker service's runtime logs.
ample logs <deployment_id> --kind runtime
EXAMPLES
Tested examples
- Spring Boot web + worker fixture (
tests/deploy-canaries/spring-boot-worker): A Spring Boot web app (apps/web) and a worker process (apps/worker) sharing one managed PostgreSQL database; the queue module is under tests/deploy-canaries/_pattern-modules.
SUCCESS CHECKS
How to know it worked
- web service responds on its public URL (
/on the live URL, expect ample canary spring boot patterns) - worker consumed the enqueued job (
/p/worker-queue/statuson the live URL, expect worker=done attempts=1 result=processed-by-worker)
LIMITATIONS
Know the limits
- 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 (your job payloads, retry policy and scheduling) is application code and was not separately tested; the worker-queue check is what was verified.
- The worker is a single long-running process supervised in its own microVM; there is no scheduler, cron or horizontal worker scaling in this recipe, and the check ran immediately after deploy so idle behavior of the worker VM is not verified.
- The worker service is private: it has no public URL and is reached only through the shared database; both services are placed with their database.
- Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.
- Region, compliance attestations and request-duration limits are unknown and not claimed.
COST
Cost estimate
Estimated 15.00 USD per month (size prices from pricing.toml at build revision a1b8c38919e59cd035ebabaced73cf84ece24371).
- web server x1
s-1vcpu-1gb: 5.00 USD - worker server x1
s-1vcpu-1gb: 5.00 USD - managed PostgreSQL database x1
s-1vcpu-1gb: 5.00 USD
Always-on monthly price of the tested sizes for the web service, the worker service and the database; apps auto-pause when idle.
EVIDENCE
Verification evidence
- canary_run on 2026-09-20T22:41:46Z at revision
af6f45adea26-dirty (CLI af6f45a): Spring Boot web service plus a separate Spring Boot worker process deployed on Ample withample plan --writethenample up(./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 web service enqueued a job that the private worker service consumed from the shared managed PostgreSQL database. Pattern proof: 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). (expires 2027-03-19T22:41:46Z)
EXECUTION
Execution binding
MCP tool ample_up (registry mcp:ample_up), schema hash db7ca0facfe2cd28 observed 2026-09-21T03:19:59.525781+00:00 at revision 49962bcade4f. Binding state at export: current. Required scopes: servers:write, databases:write.
NEXT ACTIONS
Typed next actions
- Browse the catalog index (
GET /v1/catalogon the api origin; authentication not required, approval not required) - Search published recipes by intent, stack and constraints (
POST /v1/catalog/searchon the api origin; authentication not required, approval not required) - Prepare a side-effect-free deployment plan for an authorized project (
POST /v1/catalog/planon the api origin; authentication required, approval not required) - Read the existing agent authentication setup (
GET /mcp/setupon the api origin; authentication not required, approval not required) - Browse Mobile backend (
GET /v1/catalog/nodes/workload%3Amobile-backendon the api origin; authentication not required, approval not required) - Browse Spring Boot (
GET /v1/catalog/nodes/stack%3Aframework-spring-booton the api origin; authentication not required, approval not required) - Browse Dedicated worker process (
GET /v1/catalog/nodes/pattern%3Adedicated-worker-processon the api origin; authentication not required, approval not required) - Browse Deploy API (
GET /v1/catalog/nodes/intent%3Adeploy-apion the api origin; authentication not required, approval not required)