page:recipes:rest api:fastify:response streaming

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

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

Success Checks

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

Evidence Summary

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