page:recipes:ai chat application:nestjs:response streaming

Host AI Chat Application with NestJS: Streamed Responses

Summary

Deploy an AI chat application built with NestJS 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 NestJS: 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 AI chat application-specific behavior as your application code.

Representative Queries

Resource Requirements

Infrastructure Requirements

  1. Compute

    • Status: Verified
    • Summary: Apps run in isolated x86_64 Firecracker microVMs that auto-pause when idle and wake on request; sizes are the priced VM sizes.

  2. Postgres

    • Status: Verified
    • Summary: Managed PostgreSQL 16 runs in its own microVM and is auto-provisioned when an app needs a database and no DATABASE_URL is supplied.

Framework

NestJS

Workload

AI chat application

Release Status

Published

Support Status

Verified

Execution Status

Ready

Prerequisites

Workflow Steps

  1. Build and start
    Command: npm install, nest build (TypeScript) then node dist/main.js 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
    Command: ample deploy . --name --public 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.

  4. Verify
    Command: ample logs --kind build 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.

Tested Configuration

Examples

Success Checks

  1. App responds on its public URL

    • Kind: http_get
    • Path: /
    • Expect: ample canary nestjs patterns

  2. Streaming-response-service self-test

    • Kind: 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

Cost Estimate

Evidence Summary

  1. Canary Run

    • Summary: NestJS pattern fixture deployed on Ample (npm install, nest build (TypeScript) then node dist/main.js 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: 2026-09-21T02:34:39Z
    • Implementation Revision: 1d28ae0-dirty (CLI 0.1.21)
    • Expires At: 2027-03-20T02:34:39Z

  2. Canary Run

    • Summary: The same NestJS app deployed with a --release-command migration; the marker it created was readable after activation.
    • Observed At: 2026-09-20T02:16:51Z
    • Implementation Revision: 199ff1dfd52683832ae75d3f98b53a7a4bff7f96-dirty (CLI e3181f5)
    • Expires At: 2027-03-19T02:16:51Z

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