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