## Host mobile backend with Axum: streamed responses

Deploy a mobile backend built with Axum on Ample using the streaming response service 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 Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=true). Not separately tested: your event schema, reconnection strategy and any per-request duration ceiling beyond the 70 seconds measured; treat the mobile backend-specific behavior as your application code.

### Representative Queries
- Host mobile backend with Axum: streamed responses
- Where can I host Mobile backend built with Axum?
- I need a tested end-to-end streaming transport, timeout behavior and client disconnect handling.

### Resource Requirements
- primitive:compute
- primitive:postgres

### Infrastructure Requirements
1. **Compute**  
   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**  
   Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

### Framework
- Axum

### Workload
- Mobile backend

### Release Status
- published

### Support Status
- verified

### Execution Status
- ready

### 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

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

### 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 streaming response service: a Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=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.  
   Command: ample deploy . --name  --public
4. **Verify**  
   Fetch the live URL and the pattern self-test route(s) (/p/streaming-response-service) from the example; then run your own checks. On failure read `ample logs  --kind build` then `--kind runtime`.  
   Command: ample logs  --kind build

### Success Checks
1. **App responds on its public URL**  
   Kind: http_get  
   Path: /  
   Expect: ample canary axum patterns  
2. **Streaming-response-service self-test**  
   Kind: http_get  
   Path: /p/streaming-response-service  
   Expect: an SSE stream: data: id=, then chunk events one interval apart (read incrementally: first chunk within seconds, chunks spread over the interval), then data: done; /status?id= reports sent=N disconnected=true|false done=true|false

### 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 event schema, reconnection strategy and any per-request duration ceiling beyond the 70 seconds measured) 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  
- **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: 5.0  
   - **Managed PostgreSQL database**  
     - Size: s-1vcpu-1gb  
     - Quantity: 1.0  
     - Monthly Amount: 5.0  
- **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**: 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 streaming-response-service and configuration-secrets. Pattern proof: a Server-Sent Events endpoint read incrementally through the public HTTPS gateway: five one-second chunks arrived spread over time with the first within seconds (not buffered), a 70-second stream of 36 chunks completed past common 60-second idle timeouts, and a client that disconnected after two chunks was observed and recorded by the server (disconnected=true).
2. **Canary Run**: The same Axum app deployed with a --release-command migration; the marker it created was readable after activation.

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

### Formats
- **HTML**: [Link](/content/recipes/mobile-backend/axum/response-streaming/index.html)  
- **Markdown**: [Link](/content/recipes/mobile-backend/axum/response-streaming.md)  
- **JSON**: [Link](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Amobile-backend%3Aaxum%3Aresponse-streaming)

### Next Actions
1. **Browse the catalog index**  
   Action ID: browse-catalog  
   Operation ID: catalog_index  
   Method: GET  
   Relative Path: /v1/catalog  
2. **Search published recipes by intent, stack and constraints**  
   Action ID: search-recipes  
   Operation ID: search_recipes  
   Method: POST  
   Relative Path: /v1/catalog/search  
   Parameters:  
   ```
   {"body":{"limit":5,"query":"Host mobile backend with Axum: streamed responses"}}  
   ```
3. **Prepare a side-effect-free deployment plan for an authorized project**  
   Action ID: plan:page:recipes:mobile-backend:axum:response-streaming  
   Operation ID: plan_deployment  
   Method: POST  
   Relative Path: /v1/catalog/plan  
   Parameters:  
   ```
   {"body":{"inputs":{},"projectId":"","recipeId":"page:recipes:mobile-backend:axum:response-streaming","recipeRevision":"r1"}}  
   ```
4. **Read the existing agent authentication setup**  
   Action ID: auth-setup  
   Operation ID: existing_auth_setup  
   Method: GET  
   Relative Path: /mcp/setup  
5. **Browse Mobile backend**  
   Action ID: browse:workload:mobile-backend  
   Operation ID: browse_node  
   Method: GET  
   Relative Path: /v1/catalog/nodes/workload%3Amobile-backend  
6. **Browse Axum**  
   Action ID: browse:stack:framework-axum  
   Operation ID: browse_node  
   Method: GET  
   Relative Path: /v1/catalog/nodes/stack%3Aframework-axum  
7. **Browse Streaming response service**  
   Action ID: browse:pattern:streaming-response-service  
   Operation ID: browse_node  
   Method: GET  
   Relative Path: /v1/catalog/nodes/pattern%3Astreaming-response-service  
8. **Browse Deploy API**  
   Action ID: browse:intent:deploy-api  
   Operation ID: browse_node  
   Method: GET  
   Relative Path: /v1/catalog/nodes/intent%3Adeploy-api