page:recipes:graphql api:fastapi:worker state

Host GraphQL API with FastAPI: Worker Execution and Job State

Deploy a GraphQL API built with FastAPI 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 FastAPI: 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 GraphQL API-specific behavior as your application code.

Representative Queries

Resource Requirements

Infrastructure Requirements

Framework

Workload

Release Status

Support Status

Execution Status

Prerequisites

  1. 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 (pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template; the worker starts with python3 worker.py and binds no port).
  2. 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.
  3. An Ample account token with servers:write and databases:write (ample up creates the database).

Tested Configuration

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]. Python services also need an explicit start command in the manifest (the fixture sets start for both services).

    • 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

Success Checks

Limitations

Cost Estimate

Evidence Summary

Last Verified At

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