# spark-control runbook

Operating notes for running and maintaining the cluster via spark-control.

## Day-to-day

- The UI lives at `http://<your-start9>.local:9999` once the StartOS package is installed and configured.
- Status auto-refreshes every 5 s.
- A swap takes 3–6 minutes depending on the model. Don't close the tab — but if you do, the swap continues; reopen and you'll re-attach to the log stream.

## Adding a new model

1. Add an entry to `models.yaml` (in the image source) or, post-install, via the "Edit Model Catalog" action in StartOS.
2. Confirm the weights are on the Spark: `ssh <spark-user>@<spark-1-host>.local 'ls ~/.cache/huggingface/hub/'`. If not, download with `./hf-download.sh <repo>` on Spark 1.
3. The new model appears in the UI on next refresh.

## Manual swap fallback

If the UI is unavailable and you need to swap by hand:

```bash
ssh <spark-user>@<spark-1-host>.local
cd ~/spark-vllm-docker
./launch-cluster.sh stop
./launch-cluster.sh --solo -d exec vllm serve RedHatAI/gemma-4-31B-it-NVFP4 \
  --port 8888 --host 0.0.0.0 --gpu-memory-utilization 0.8 \
  --max-model-len 32768 --reasoning-parser gemma4 \
  --tool-call-parser gemma4 --enable-auto-tool-choice
docker logs -f vllm_node      # wait for "Application startup complete."
```

## Diagnostics

```bash
# Is vLLM serving?
curl -s http://<spark-1-ip>:8888/v1/models | jq .

# Cluster status (containers up?)
ssh <spark-user>@<spark-1-host>.local 'cd ~/spark-vllm-docker && ./launch-cluster.sh status'

# Tail current model's logs
ssh <spark-user>@<spark-1-host>.local 'docker logs --tail 200 -f vllm_node'

# Parakeet
curl -s http://<spark-2-ip>:8000/health

# Magpie (see known-issues.md)
curl -s http://<spark-2-ip>:9000/v1/health/ready
```

## Hard reset

If launch-cluster.sh gets stuck:

```bash
ssh <spark-user>@<spark-1-host>.local
cd ~/spark-vllm-docker
./launch-cluster.sh stop
docker ps -aq | xargs -r docker rm -f
# then relaunch your preferred model
```