spark-control

A browser-based control panel for a dual-DGX-Spark vLLM cluster. Designed to run as a StartOS 0.4 package on a Start9 server on the same LAN as the Sparks.

What it does

• Shows which LLM is currently loaded on the cluster (:8888/v1/models).
• Click to swap to a different model — stops the current one, launches the new one, streams logs to the UI until Application startup complete. appears.
• Surfaces health for Parakeet (STT, :8000) and Magpie (TTS, :9000) on Spark 2.

Architecture

[Browser/phone] ──► [StartOS reverse proxy] ──► [spark-control container]
                                                       │  (SSH over LAN)
                                                       ▼
                                                  [Spark 1] ──► launch-cluster.sh
                                                       │
                                                       ▼
                                                  [Spark 2]

Two layers in this repo:

• image/ — a self-contained FastAPI app + static UI. Runs anywhere with uvicorn and an SSH client. Useful for development.
• package/ — a thin StartOS 0.4 wrapper that packages the image, exposes the UI on the LAN, and gives the user actions to configure SSH access to the Sparks.

Quick start (local dev, no StartOS yet)

cd image
python3 -m venv .venv && source .venv/bin/activate
pip install -e .
export SPARK1_HOST=<spark-1-ip>
export SPARK1_USER=<spark-user>
export SPARK2_HOST=<spark-2-ip>
export SPARK2_USER=<spark-user>
export SSH_KEY_PATH="$HOME/Library/Application Support/NVIDIA/Sync/config/nvsync.key"
uvicorn app.server:app --host 0.0.0.0 --port 9999 --reload

Open http://localhost:9999.

Note: use the IP <spark-1-ip> for Spark 1, not <spark-1-host>.local. mDNS resolves to IPv6 first and httpx hangs on it because vLLM only binds IPv4.

Build the StartOS package

cd package
npm i        # one-time
make x86     # produces spark-control_x86_64.s9pk (~55 MB)

Requires start-cli, Node ≥ 22, Docker. The build runs tsc + ncc for the TS bundle, then docker build on image/Dockerfile, then start-cli s9pk pack to produce the .s9pk.

To sideload onto your Start9: make install (needs host: set in ~/.startos/config.yaml), or upload the .s9pk via the Start9 web UI's sideload feature.

Post-install setup (one-time per Start9 install)

1. Open the Spark Control service → Actions → Show Public Key → copy the line.
2. SSH to each Spark and append the line to ~/.ssh/authorized_keys for the <spark-user> user.
3. Actions → Configure Sparks → enter <spark-1-ip> / <spark-user> for Spark 1 and <spark-2-ip> / <spark-user> for Spark 2.
4. Start the service. Open the Web UI — current model + health should show within ~5 s.

Repo layout

• image/ — Docker image source (FastAPI app + models.yaml)
• package/ — StartOS 0.4 package source
• runbook.md — operating notes
• known-issues.md — known quirks and workarounds
• LICENSE — MIT

Status

v0.1 — local-only, single-cluster, no auth (trusts LAN). Five LLMs in the catalog: qwen3-vl (cluster), gemma4, qwen36, plus two legacy entries. Magpie surfaces red until its container is fixed.

v0.2 backlog (in runbook.md / commits): Parakeet/Magpie lifecycle controls, configurable flag tiers in UI, Open WebUI integration, magpie-tts fix.