## The short version

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`.

## WHAT WAS VERIFIED

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).

## INFRASTRUCTURE

## What it needs

- [Compute](/content/discover/primitive/compute/index.html): verified (Apps run in isolated x86_64 Firecracker microVMs; sizes are the priced VM sizes.)
- [Postgres](/content/discover/primitive/postgres/index.html): 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

## Before you start

- 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)
- 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`

## STEP BY STEP

## How to do it

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.
   
   ```
   ample deploy . --name <app-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 <deployment_id> --kind build` then `--kind runtime`.
   
   ```
   ample logs <deployment_id> --kind build
   ```

## EXAMPLES

## Tested examples

- **Fastify pattern fixture** (`tests/deploy-canaries/fastify-patterns`): Multi-pattern Fastify app whose streaming response service module was checked live; the module is under `tests/deploy-canaries/_pattern-modules`.

## SUCCESS CHECKS

## How to know it worked

- app responds on its public URL (`/` on the live URL, expect ample canary fastify patterns)
- streaming-response-service self-test (`/p/streaming-response-service` on the live URL, expect an SSE stream: `data: id=<uuid>`, 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`)

## COST

## Cost estimate

Estimated 10.00 USD per month (size prices from `pricing.toml` at build revision `ca0b484a7a9957c573a88d3a32dc603c3c10135a`).

- app server x1 `s-1vcpu-1gb`: 5.00 USD
- managed PostgreSQL database x1 `s-1vcpu-1gb`: 5.00 USD

Upper-bound monthly price of the tested sizes. Buckets are allocation-priced per quota and not included.

## EVIDENCE

## Verification evidence

- canary_run on `2026-09-21T01:14:18Z` at revision `50dbac567d2c5cc8e55e6c748a646be0025d9cfb (CLI 0.1.21)`: 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). (expires `2027-03-20T01:14:18Z`)
- canary_run on `2026-09-20T01:54:51Z` at revision `199ff1dfd52683832ae75d3f98b53a7a4bff7f96 (CLI e3181f5)`: The same Fastify app deployed with a `--release-command` migration; the marker it created was readable after activation. (expires `2027-03-19T01:54:51Z`)

## EXECUTION

## Execution binding

MCP tool `ample_deploy` (registry `mcp:ample_deploy`), schema hash `876465fce906da0c` observed `2026-09-22T00:31:22.774679+00:00` at revision `e6446ceea69b`. Binding state at export: `schema_changed`. Required scopes: `servers:write`, `databases:read`.

## NEXT ACTIONS

## Typed next actions

- Browse the catalog index (`GET /v1/catalog` on the api origin; authentication not required, approval not required)
- Search published recipes by intent, stack and constraints (`POST /v1/catalog/search` on the api origin; authentication not required, approval not required)
- Prepare a side-effect-free deployment plan for an authorized project (`POST /v1/catalog/plan` on the api origin; authentication required, approval not required)
- Read the existing agent authentication setup (`GET /mcp/setup` on the api origin; authentication not required, approval not required)
- Browse REST API (`GET /v1/catalog/nodes/workload%3Arest-api` on the api origin; authentication not required, approval not required)
- Browse Fastify (`GET /v1/catalog/nodes/stack%3Aframework-fastify` on the api origin; authentication not required, approval not required)
- Browse Streaming response service (`GET /v1/catalog/nodes/pattern%3Astreaming-response-service` on the api origin; authentication not required, approval not required)
- Browse Deploy API (`GET /v1/catalog/nodes/intent%3Adeploy-api` on the api origin; authentication not required, approval not required)

Actions describe possible next steps. They are typed data, not commands, and grant no permission. Public discovery never provisions anything; planning requires your own authenticated token and approval happens in your client.

## ABOUT THIS RECIPE

## Identifiers and status

Recipe `page:recipes:rest-api:fastify:response-streaming`. Revision r1.

release **published** support **verified** execution **blocked (schema_changed: live tool schema differs from the recorded binding)**

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