# Host REST API with Axum: Stored Input and Output Artifacts

## Summary
Deploy a REST API built with Axum on Ample using the generated downloads 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, a private S3-compatible bucket holds objects with credentials delivered as encrypted environment variables. Verified on Axum: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Not separately tested: your export formats, retention policy and entitlement model; treat the REST API-specific behavior as your application code.

## Representative Queries
- Host REST API with Axum: stored input and output artifacts
- Where can I host REST API built with Axum?
- I need an input/output artifact contract, object metadata and access boundaries.

## Resource Requirements
- primitive:compute
- primitive:postgres
- primitive:s3-compatible-object-storage

## Infrastructure Requirements
### Compute
- **Status:** verified  
- **Summary:** Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.

### Postgres
- **Status:** verified  
- **Summary:** Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

### S3-compatible Object Storage
- **Status:** verified  
- **Summary:** Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

## 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 generated downloads: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3). Copy the approach into your schema; keep migrations idempotent and run them with --release-command.

3. **Wire Object Storage**  
   Create the bucket(s), then pass endpoint, region, bucket and keys as --env values. Use path-style addressing. Keep private data in an unpublished bucket.

4. **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.  
   ```bash
   ample deploy . --name  --public --env S3_ENDPOINT=... --env S3_REGION=... --env S3_BUCKET=... --env S3_ACCESS_KEY_ID=... --env S3_SECRET_ACCESS_KEY=...
   ```

5. **Verify**  
   Fetch the live URL and the pattern self-test route(s) (/p/generated-downloads) from the example; then run your own checks. On failure read `ample logs  --kind build` then `--kind runtime`.  
   ```bash
   ample logs  --kind build
   ```

## Examples
- **Axum Pattern Fixture**  
  Multi-pattern Axum app whose generated downloads module was checked live; the module is under tests/deploy-canaries/_pattern-modules.  
  - **Source Reference:** tests/deploy-canaries/axum-patterns

## Success Checks
- **App responds on its public URL**  
  - **Kind:** http_get  
  - **Path:** /  
  - **Expect:** ample canary axum patterns
- **Generated-downloads self-test**  
  - **Kind:** http_get  
  - **Path:** /p/generated-downloads  
  - **Expect:** export=ok rows=3 (with ?token=...; 401 without)

## 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 export formats, retention policy and entitlement model) 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.
- PutObject and GetObject with path-style addressing are verified; multipart upload, listing, presigned URLs and lifecycle rules are not.

## Cost Estimate
- **Monthly Amount:** $10.00  
- **Currency:** USD  
- **Basis:** size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty.  
- **Components:**  
  - **App Server:**  
    - **Size:** s-1vcpu-1gb  
    - **Quantity:** 1.0  
    - **Monthly Amount:** $5.00  
  - **Managed PostgreSQL Database:**  
    - **Size:** 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. Buckets are allocation-priced per quota and not included.

## Evidence Summary
- **Canary Run**  
  - **Summary:** Axum pattern fixture deployed on Ample (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); checks passed for generated-downloads and configuration-secrets. Pattern proof: an export query rendered to a CSV artifact stored with metadata in a private bucket and returned only to an authorized caller (401 without token, export=ok rows=3).  
  - **Observed At:** 2026-09-21T02:46:37Z  
  - **Implementation Revision:** 1d28ae0-dirty (CLI 0.1.21)  
  - **Expires At:** 2027-03-20T02:46:37Z

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