page:recipes:ai chat application:spring boot:worker state

Host ai chat application with Spring Boot: worker execution and job state

Summary

Deploy an AI chat application 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 AI chat application-specific behavior as your application code.

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

• 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)

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. Exit 2 means it left questions in the manifest; answer them with --answer or by editing the file.
   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; exit 0 means everything applied, 2 needs input, 1 a failed resource (independent siblings still proceed and re-running resumes).
   Command: 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.
   Command: ample logs --kind runtime

Examples

• Spring Boot web + worker fixture: 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

• Web service responds on its public URL
• Worker consumed the enqueued job

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 AI chat application 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.

Cost Estimate

• Monthly Amount: $15.00
• Basis: size prices from pricing.toml at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty

Always-on monthly price of the tested sizes for the web service, the worker service and the database; apps auto-pause when idle.

Evidence Summary

• Spring Boot web service plus a separate Spring Boot worker process deployed on Ample with ample plan --write then ample up, consuming a jobs table with row locks and marking jobs done once (worker=done attempts=1).

Last Verified At

• 2026-09-20T22:41:46Z