# Host mobile backend with NestJS: streamed responses

Deploy a mobile backend built with NestJS 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 NestJS: 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.

## Summary
- **Framework**: NestJS
- **Workload**: Mobile backend
- **Release Status**: published
- **Support Status**: verified
- **Execution Status**: ready

## Representative Queries
- Host mobile backend with NestJS: streamed responses
- Where can I host Mobile backend built with NestJS?
- 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**
   - 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 NestJS project that builds and starts with the documented commands (npm install, nest build (TypeScript) then node dist/main.js on the node-22 template)
- 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**: node-22 
- **Runtime**: node 
- **Size**: s-1vcpu-1gb 
- **Install**: npm install 
- **Build**: npm run build --if-present 
- **Start**: npm run start

## Workflow Steps
1. **Build and start**  
npm install, nest build (TypeScript) then node dist/main.js on the node-22 template. 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 nestjs 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 node-22 template at s-1vcpu-1gb with the example fixture; other sizes, templates and NestJS 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.

## Cost Estimate
- **Currency**: USD 
- **Monthly Amount**: 10.0 
- **Basis**: size prices from pricing.toml (loaded by the API) at build revision 1ac5595375130d45290090e82ed0f554ccd45405-dirty

### Components
1. App server
   - Size: s-1vcpu-1gb 
   - Quantity: 1.0 
   - Monthly Amount: 5.0 
2. 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.

## Evidence Summary
1. **Canary Run** 
   - Summary: NestJS pattern fixture deployed on Ample; checks passed for streaming-response-service and configuration-secrets. 
   - Observed At: 2026-09-21T02:34:39Z

2. **Canary Run** 
   - Summary: The same NestJS app deployed with a --release-command migration; the marker it created was readable after activation. 
   - Observed At: 2026-09-20T02:16:51Z

## Next Actions
1. **Browse the catalog index** 
   - Operation: catalog_index 
   - Method: GET 
   - Relative Path: /v1/catalog 
 
2. **Search published recipes by intent, stack and constraints** 
   - Operation: search_recipes 
   - Method: POST 
   - Relative Path: /v1/catalog/search

3. **Prepare a side-effect-free deployment plan for an authorized project** 
   - Operation: plan_deployment 
   - Method: POST 
   - Relative Path: /v1/catalog/plan

4. **Read the existing agent authentication setup** 
   - Operation: existing_auth_setup 
   - Method: GET 
   - Relative Path: /mcp/setup

5. **Browse Mobile backend** 
   - Operation: browse_node 
   - Method: GET 
   - Relative Path: /v1/catalog/nodes/workload%3Amobile-backend

6. **Browse NestJS** 
   - Operation: browse_node 
   - Method: GET 
   - Relative Path: /v1/catalog/nodes/stack%3Aframework-nestjs

7. **Browse Streaming response service** 
   - Operation: browse_node 
   - Method: GET 
   - Relative Path: /v1/catalog/nodes/pattern%3Astreaming-response-service

8. **Browse Deploy API** 
   - Operation: browse_node 
   - Method: GET 
   - Relative Path: /v1/catalog/nodes/intent%3Adeploy-api