# Host REST API with Axum: Worker Execution and Job State

## Summary
Deploy a REST API 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 REST API-specific behavior as your application code.

## Representative Queries
- Host REST API with Axum: worker execution and job state
- Where can I host REST API 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
1. **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.
2. **Postgres**  
   Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.

## 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`

## Input Schema
- `path`: Directory containing ample.toml (the whole topology is applied)
- `wait_secs`: Maximum seconds to wait for each service deployment

## Examples
1. **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:** `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 with the example fixture; other sizes, templates and Axum major versions are 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.

## Cost Estimate
- **Currency:** USD
- **Monthly Amount:** 15.0
- **Basis:** Size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty

### Components
1. **Web server**  
   - **Size:** s-1vcpu-1gb  
   - **Monthly Amount:** 5.0
2. **Worker server**  
   - **Size:** s-1vcpu-1gb  
   - **Monthly Amount:** 5.0
3. **Managed PostgreSQL database**  
   - **Size:** s-1vcpu-1gb  
   - **Monthly Amount:** 5.0

## Next Actions
- **Browse the catalog index**  
- **Search published recipes by intent, stack and constraints**  
- **Prepare a side-effect-free deployment plan for an authorized project**  
- **Read the existing agent authentication setup**  
- **Browse REST API**  
- **Browse Axum**  
- **Browse Dedicated worker process**  
- **Browse Deploy API**