# Host mobile backend with Axum: Postgres-backed state

Deploy a mobile backend 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 mobile backend-specific behavior as your application code.

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

## Resource Requirements
- **Compute**
- **Postgres**

## Infrastructure Requirements
1. **Compute**  \- Verified  \- Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.
2. **Postgres**  \- Verified  \- 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
- A 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.
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`.

## Success Checks
- app responds on its public URL (kind: http_get, path: /, expect: ample canary axum patterns)
- durable-job-state self-test (kind: http_get, path: /p/durable-job-state, expect: job=done attempts=1 idempotent=true)

## 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 mobile backend itself (your job types, payload schema and retry policy) is application code and was not separately tested; the pattern checks are what was verified.
- Region, compliance attestations and request-duration limits are unknown and not claimed.
- Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
- Managed PostgreSQL 16 only; extensions, connection limits and backup or restore procedures are not verified; apps and their databases are placed together.

## Cost Estimate
- **Currency**: USD
- **Monthly Amount**: 10.0 \- Always-on monthly price of the tested sizes; apps and databases auto-pause when idle. Buckets are allocation-priced per quota and not included.

### Cost Components
- app server (size: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0)
- managed PostgreSQL database (size: s-1vcpu-1gb, quantity: 1.0, monthlyAmount: 5.0)

## Evidence Summary
- **Canary Run**  \- Axum pattern fixture deployed on Ample; checks passed for durable-job-state and configuration-secrets.
- **Canary Run**  \- The same Axum app deployed with a --release-command migration; the marker it created was readable after activation.