## Host ai chat application with Axum: stored input and output artifacts

### Summary
Deploy a AI chat application 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 AI chat application-specific behavior as your application code.

### Representative Queries
- Host AI chat application with Axum: stored input and output artifacts
- Where can I host AI chat application 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**  
  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.
- **S3-compatible object storage**  
  Buckets are S3-compatible with issued credentials; PutObject and GetObject are verified by canary. Other S3 operations are not verified.

### 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).
- A bucket from `ample bucket create` with its credentials passed as encrypted S3_* environment variables.
- An Ample account token with servers:write, databases:read, buckets:read.

### Workflow Steps
1. **Build and start**  
   `cargo build --release` in the rust builder image, 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.  
   `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); 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 generated downloads module was checked live; the module is under tests/deploy-canaries/_pattern-modules.

### Success Checks
- app responds on its public URL: **HTTP Get** to `/` expecting `ample canary axum patterns`
- generated-downloads self-test: **HTTP Get** to `/p/generated-downloads` expecting `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 AI chat application 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 verified.

### Cost Estimate
- **Monthly Cost**: $10.00 USD  
  **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**: Axum pattern fixture deployed on Ample; checks passed for generated-downloads and configuration-secrets.
  - Observed At: 2026-09-21T02:46:37Z
  - Expires At: 2027-03-20T02:46:37Z
  - Implementation Revision: 1d28ae0-dirty (CLI 0.1.21)

### Formats
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- [Markdown Version](/content/recipes/ai-chat-application/axum/artifact-storage.md)
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