page:recipes:mobile backend:fastify:response streaming

Host mobile backend with Fastify: streamed responses

Deploy a mobile backend 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 mobile backend-specific behavior as your application code.

Prerequisites

• 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

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 to 0.0.0.0 on PORT.
2. Implement the pattern on PostgreSQL: The fixture's module implements a streaming response service: a Server-Sent Events endpoint read incrementally through the public HTTPS gateway.
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) from the example; then run your own checks.

Limitations

• Verified on the node-22 template at s-1vcpu-1gb with the example fixture; other sizes, templates and Fastify 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.

Cost Estimate

• Currency: USD
• Monthly Amount: 10.0
• Components:
  • App server: size s-1vcpu-1gb, quantity 1, monthly amount 5.0
  • Managed PostgreSQL database: size s-1vcpu-1gb, quantity 1, monthly amount 5.0

Success Checks

• App responds on its public URL.
• Streaming-response-service self-test.

Examples

• Fastify pattern fixture: Multi-pattern Fastify app whose streaming response service module was checked live.

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