## The short version

Deploy a REST API built with Echo 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 Echo: 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

- An Echo project that builds and starts with the documented commands (CGO_ENABLED=0 go build -o app ./... then ./app on the ubuntu-24.04 template (go.sum committed for a reproducible build))
- 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**  
   CGO_ENABLED=0 go build -o app ./... then ./app on the ubuntu-24.04 template (go.sum committed for a reproducible build). 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

- **Echo pattern fixture** (`tests/deploy-canaries/echo-patterns`): Multi-pattern Echo 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 echo 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 2026-09-21T02:34:39Z at revision `1d28ae0 (CLI 0.1.21)`: Echo pattern fixture deployed on Ample (CGO_ENABLED=0 go build -o app ./... then ./app on the ubuntu-24.04 template (go.sum committed for a reproducible build)); 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 2027-03-20T02:34:39Z)
- canary_run on 2026-09-20T02:43:30Z at revision `199ff1dfd52683832ae75d3f98b53a7a4bff7f96 (CLI b75e104)`: The same Echo app deployed with a --release-command migration; the marker it created was readable after activation. (expires 2027-03-19T02:43:30Z)

## 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 Echo (`GET /v1/catalog/nodes/stack%3Aframework-echo` 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)

### About this recipe

## Identifiers and status

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

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

Formats: [HTML](/content/recipes/rest-api/echo/response-streaming/index.html) | [Markdown](/content/recipes/rest-api/echo/response-streaming.md) | [JSON contract](https://api.ample.computer/v1/catalog/recipes/page%3Arecipes%3Arest-api%3Aecho%3Aresponse-streaming)