# Host graphql api with Starlette: worker execution and job state

## Summary
Deploy a graphql api built with Starlette 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 Starlette: 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
- Host graphql api with Starlette: worker execution and job state
- Where can I host GraphQL API built with Starlette?
- I need a separately runnable worker, durable job records and idempotent retries; not a managed queue.

## 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.

## Framework
Starlette

## Workload
GraphQL API

## 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 (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)
- 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]`. 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
- **Starlette web + worker fixture**: A Starlette 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**  
  Kind: http_get  
  Path: `/`  
  Expect: `ample canary starlette patterns`
- **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 python-3.12 template at s-1vcpu-1gb for both services with the example fixture; other sizes, templates and Starlette major versions are not verified.
- The graphql api 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 Estimate
- Currency: USD
- Monthly Amount: 15.0
- Authoritative: true
- Basis: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
- Components:
  - Web server: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0
  - Worker server: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0
  - Managed PostgreSQL database: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0
- Note: Always-on monthly price of the tested sizes for the web service, the worker service and the database; apps auto-pause when idle.

## Evidence Summary
- **Canary Run**: Starlette web service plus a separate Python worker process deployed on Ample with `ample plan --write` then `ample up` (pip install into .ample/python from requirements.txt, then uvicorn from run.py reading PORT on the python-3.12 template); 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).  
  Observed At: 2026-09-20T03:56:46Z  
  Implementation Revision: 03b6402b1b3e19178985f08ea4033804521d85d4-dirty (CLI b75e104)  
  Expires At: 2027-03-19T03:56:46Z  
  Scope:
  - Checks: [`/`,`/p/worker-queue/status`]
  - Pattern: pattern:dedicated-worker-process
  - Services: [web, worker]
  - Template: python-3.12
  - Tool: ample_up

## Last Verified At
2026-09-20T03:56:46Z

## Unknowns
- Region availability is unknown until a verified region fact is recorded
- Compliance attestations are unknown; none are claimed.

## Formats
- HTML: [https://ample.computer/recipes/graphql-api/starlette/worker-state](/content/recipes/graphql-api/starlette/worker-state/index.html)  
- Markdown: [https://ample.computer/recipes/graphql-api/starlette/worker-state.md](/content/recipes/graphql-api/starlette/worker-state.md)  
- JSON: [https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Agraphql-api%3Astarlette%3Aworker-state](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Agraphql-api%3Astarlette%3Aworker-state)

## Next Actions
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   - Operation ID: search_recipes  
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