# Host rest api with Fastify: streamed responses

Deploy a rest api built with Fastify 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 Fastify: 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 rest api-specific behavior as your application code.

## Summary

- **Framework**: Fastify  
- **Workload**: REST API  
- **Release Status**: published  
- **Support Status**: verified  
- **Execution Status**: ready

## Prerequisites

1. A Fastify project that builds and starts with the documented commands (npm install, npm run build --if-present, npm run start on the node-22 template)  
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

## Workflow Steps

1. **Build and start**  
   - `npm install`, `npm run build --if-present`, `npm run start` 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`

## Tested Configuration

- **Template**: node-22  
- **Runtime**: node  
- **Size**: s-1vcpu-1gb  
- **Install**: `npm install`  
- **Build**: `npm run build --if-present`  
- **Start**: `npm run start`

## Success Checks

- **App responds on its public URL**  
   - Type: http_get  
   - Path: `/`  
   - Expect: `ample canary fastify patterns`

- **Streaming-response-service self-test**  
   - Type: 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

1. Verified on the node-22 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Fastify major versions are not verified.
2. The rest api 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.
3. Region, compliance attestations and request-duration limits are unknown and not claimed.
4. Apps auto-pause when idle and wake on the next request; always-on is an operator setting, not a plan feature.
5. 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  
- **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

- **Kind**: canary_run  
   - **Summary**: Fastify pattern fixture deployed on Ample (npm install, npm run build --if-present, npm run start on the node-22 template); 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).
   - **Observed At**: 2026-09-21T01:14:18Z  
   - **Implementation Revision**: 50dbac567d2c5cc8e55e6c748a646be0025d9cfb-dirty (CLI 0.1.21)  
   - **Expires At**: 2027-03-20T01:14:18Z  
   - **Scope**: 
     - **Checks**: `/p/streaming-response-service`  
     - **Pattern**: pattern:streaming-response-service  
     - **Template**: node-22

## 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 rest api with Fastify: streamed responses"}`

3. **Prepare a side-effect-free deployment plan for an authorized project**  
   - Action ID: plan:page:recipes:rest-api:fastify:response-streaming  
   - Operation ID: plan_deployment  
   - Method: POST  
   - Relative Path: `/v1/catalog/plan`  
   - Parameters: 
     - Body: `{"inputs":{},"projectId":"","recipeId":"page:recipes:rest-api:fastify: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 REST API**  
   - Action ID: browse:workload:rest-api  
   - Operation ID: browse_node  
   - Method: GET  
   - Relative Path: `/v1/catalog/nodes/workload%3Arest-api`

6. **Browse Fastify**  
   - Action ID: browse:stack:framework-fastify  
   - Operation ID: browse_node  
   - Method: GET  
   - Relative Path: `/v1/catalog/nodes/stack%3Aframework-fastify`

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`