# Host AI Chat Application with Axum: Postgres-Backed State

Deploy an AI chat application 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 AI chat application-specific behavior as your application code.

## Summary
- **Family**: Workload recipe
- **Framework**: Axum
- **Workload**: AI chat application
- **Release Status**: Published
- **Support Status**: Verified
- **Execution Status**: Ready
- **Docs Only**: False

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

## Resource Requirements
- Primitive: Compute
- Primitive: Postgres

## Infrastructure Requirements
1. **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.
2. **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.

## Prerequisites
1. 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).
2. A PostgreSQL driver reading DATABASE_URL at runtime (auto-provisioned when omitted, or supplied with --env).
3. An Ample account token with servers:write, databases:read.

## Tested Configuration
- **Template**: ubuntu-24.04
- **Runtime**: rust
- **Size**: s-1vcpu-2gb
- **Build**: cargo build --release
- **Start Command**: ./$(ls target/release/*.d | grep -v '/lib' | head -n 1 | sed 's/\.d$//')

## Workflow Steps
1. **Build and Start**  
   - Body: `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**  
   - Body: 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**  
   - Command: `ample deploy . --name  --public`
4. **Verify**  
   - Command: `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
1. App responds on its public URL (`/`)
   - Expect: ample canary axum patterns
2. Durable-job-state self-test (`/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 AI chat application 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**: $10.00  
- **Authoritative**: True  
- **Basis**: size prices from pricing.toml at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty
- **Components**:  
   - App Server: 1 x s-1vcpu-1gb = $5.00  
   - Managed PostgreSQL Database: 1 x s-1vcpu-1gb = $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
1. **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 durable-job-state and configuration-secrets.
   - Observed At: 2026-09-21T02:46:37Z  
   - Implementation Revision: 1d28ae0-dirty (CLI 0.1.21)
2. **Canary Run**  
   - Summary: The same Axum app deployed with a --release-command migration; the marker it created was readable after activation.
   - Observed At: 2026-09-21T02:46:37Z  
   - Implementation Revision: 1d28ae0-dirty (CLI 0.1.21)

## Next Actions
1. **Browse the Catalog**  
   - Action ID: browse-catalog  
   - Method: GET  
   - Relative Path: /v1/catalog
2. **Search Recipes**  
   - Action ID: search-recipes  
   - Method: POST  
   - Relative Path: /v1/catalog/search
3. **Prepare Deployment Plan**  
   - Action ID: plan:page:recipes:ai-chat-application:axum:persistent-state  
   - Method: POST  
   - Relative Path: /v1/catalog/plan
4. **Read Authentication Setup**  
   - Action ID: auth-setup  
   - Method: GET  
   - Relative Path: /mcp/setup
5. **Browse AI Chat Application**  
   - Action ID: browse:workload:ai-chat-application  
   - Method: GET  
   - Relative Path: /v1/catalog/nodes/workload%3Aai-chat-application