# Host REST API with Axum: Postgres-backed state

Deploy a REST API built with Axum on Ample using the durable job state pattern. Compute runs the app in an isolated microVM behind a public HTTPS URL, a managed PostgreSQL 16 database is auto-provisioned and injected as DATABASE_URL. Verified on Axum: a jobs table with a state and attempts counter, processing inside a row-locked transaction, and a second run that is a no-op (job=done attempts=1 idempotent=true).  
Not separately tested: your job types, payload schema and retry policy; treat the REST API-specific behavior as your application code.

## Representative Queries
- Host REST API with Axum: Postgres-backed state
- Where can I host REST API built with Axum?
- I need a durable state schema and retry/recovery semantics implemented by application code.

## Resource Requirements
- Compute
- 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.

## Prerequisites
- An Axum project that builds and starts 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).
- A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env).
- An Ample account token with servers:write, databases:read.

## Workflow Steps
1. **Build and start**: 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 server must bind 0.0.0.0 on PORT.
2. **Implement the pattern on PostgreSQL**: The fixture's module implements durable job state: a jobs table with a state and attempts counter, processing inside a row-locked transaction, and a second run that is a no-op (job=done attempts=1 idempotent=true). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.
3. **Deploy**: Run the synchronous deploy once and read the result (exit 0 live, 1 failed, 2 blocked). Re-running with no change is a no-op.
   ```
   ample deploy . --name --public
   ```
4. **Verify**: Fetch the live URL and the pattern self-test route(s) (/p/durable-job-state) from the example; then run your own checks. On failure, read `ample logs --kind build`, then `--kind runtime`.
   ```
   ample logs --kind build
   ```

## Examples
- **Axum pattern fixture**: Multi-pattern Axum app whose durable job state module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

## Success Checks
- App responds on its public URL.  
- Durable-job-state self-test.

## Limitations
- Verified on the ubuntu-24.04 template at s-1vcpu-2gb with the example fixture; other sizes, templates and Axum major versions are not verified.
- The REST API itself (your job types, payload schema and retry policy) is application code and was not separately tested; the pattern checks are what was verified.

## Cost Estimate
- **Currency**: USD  
- **Monthly Amount**: $10.00  
- **Components**:  
  - App server: s-1vcpu-1gb, Quantity: 1.0, Monthly Amount: $5.00  
  - Managed PostgreSQL database: s-1vcpu-1gb, Quantity: 1.0, Monthly Amount: $5.00  
- **Note**: Always-on monthly price of the tested sizes; apps and databases auto-pause when idle.

## Evidence Summary
- **Canary Run**: Axum pattern fixture deployed on Ample; checks passed for durable-job-state and configuration-secrets.

## 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 Durable job state.
- Browse Deploy API.