# Host ai workflow runner with Axum: worker execution and job state

## Summary
Deploy an ai workflow runner built with Axum 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 Axum: 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 workflow runner-specific behavior as your application code.

## Representative Queries
- Host ai workflow runner with Axum: worker execution and job state
- Where can I host AI workflow runner built with Axum?
- 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:** Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.
- **Postgres:** Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.

## 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 (cargo build --release in the rust builder image (stable toolchain, Cargo.lock committed, pure-Rust dependencies), then the release binary on the ubuntu-24.04 template reading PORT and DATABASE_URL; the worker starts with its own release binary (plain tokio-postgres) 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)

## 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.
   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
- **Axum web + worker fixture**: A Axum 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.
  Source Ref: tests/deploy-canaries/axum-worker

## Success Checks
1. web service responds on its public URL
   - Kind: http_get
   - Path: /
   - Expect: ample canary axum 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 ubuntu-24.04 template at s-1vcpu-2gb for both services.
- The ai workflow runner itself (your job payloads, retry policy and scheduling) is application code and was not separately tested.
- The worker is a single long-running process supervised in its own microVM; there is no scheduler or horizontal worker scaling in this recipe.

## Cost Estimate
- Currency: USD
- Monthly Amount: 15.0
- Basis: size prices from pricing.toml at build revision.
- Components:
  - web server: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
  - worker server: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0
  - managed PostgreSQL database: s-1vcpu-1gb, quantity: 1.0, monthly amount: 5.0

## Evidence Summary
- **Kind:** canary_run
- **Summary:** Axum web service plus a separate Axum worker process deployed on Ample with `ample plan --write` then `ample up`.
- **Observed At:** 2026-09-21T02:46:37Z

## Last Verified At
- 2026-09-21T02:46:37Z