# ComfyUI on mRock — install + ops

ImaGen's `flux-schnell-local` backend talks to ComfyUI on mRock at
`http://mrock:8188` (Tailscale-internal). This document is the reproducible
install path from a clean mRock state.

mRock runs Arch Linux + systemd with an NVIDIA RTX 4070 Ti SUPER (16 GB
VRAM). Ollama is already a native systemd service, so ComfyUI follows the
same pattern (native Python venv + systemd unit) instead of Docker — Docker
on mRock has no `nvidia` runtime configured, and adding one is more invasive
than another systemd unit.

## Prerequisites on mRock

- Python via `uv` (already installed).
- NVIDIA driver new enough for CUDA 12.4. `nvidia-smi --query-gpu=driver_version`
  should show >= 550. Driver 595 is what mRock has today.
- ~35 GB free on `/home` for the model files.
- `ollama.service` running on port 11434 — coexistence notes below.

## 1. Clone ComfyUI + Python venv

```bash
mkdir -p ~/dev && cd ~/dev
git clone --depth 1 https://github.com/comfyanonymous/ComfyUI.git comfyui
cd comfyui
uv venv --python 3.12 .venv
source .venv/bin/activate.fish

# PyTorch CUDA 12.4 wheels — match the system driver
uv pip install --no-cache torch torchvision torchaudio \
    --index-url https://download.pytorch.org/whl/cu124

uv pip install --no-cache -r requirements.txt
```

Verify CUDA is wired up:

```bash
.venv/bin/python -c \
  "import torch; print(torch.__version__, torch.cuda.is_available(), torch.cuda.get_device_name(0))"
# expected: 2.6.0+cu124 True NVIDIA GeForce RTX 4070 Ti SUPER
```

## 2. Models — FLUX.1 schnell

The Black-Forest-Labs primary repo (`black-forest-labs/FLUX.1-schnell`) is
**gated** — `curl` against it without an HF token returns HTTP 401. We pull
the weights from ungated mirrors of the same Apache-2.0 release.

| File | Where it goes | Source |
|------|---------------|--------|
| `flux1-schnell.safetensors` (~23.8 GB, fp16) | `models/unet/` | `Comfy-Org/flux1-schnell` |
| `ae.safetensors` (~335 MB) | `models/vae/` | `sirorable/flux-ae-vae` |
| `clip_l.safetensors` (~246 MB) | `models/clip/` | `comfyanonymous/flux_text_encoders` |
| `t5xxl_fp8_e4m3fn.safetensors` (~4.9 GB) | `models/clip/` | `comfyanonymous/flux_text_encoders` |

```bash
cd ~/dev/comfyui/models

curl -L -o unet/flux1-schnell.safetensors \
  https://huggingface.co/Comfy-Org/flux1-schnell/resolve/main/flux1-schnell.safetensors
curl -L -o vae/ae.safetensors \
  https://huggingface.co/sirorable/flux-ae-vae/resolve/main/ae.safetensors
curl -L -o clip/clip_l.safetensors \
  https://huggingface.co/comfyanonymous/flux_text_encoders/resolve/main/clip_l.safetensors
curl -L -o clip/t5xxl_fp8_e4m3fn.safetensors \
  https://huggingface.co/comfyanonymous/flux_text_encoders/resolve/main/t5xxl_fp8_e4m3fn.safetensors
```

If a new HF token is configured later (`~/.cache/huggingface/token`), the
official `black-forest-labs/FLUX.1-schnell` URL is byte-identical and can be
swapped in.

## 3. systemd unit

Drop `/etc/systemd/system/comfyui.service`:

```ini
[Unit]
Description=ComfyUI image generation server
Documentation=https://github.com/comfyanonymous/ComfyUI
After=network-online.target
Wants=network-online.target

[Service]
Type=simple
User=m
Group=m
WorkingDirectory=/home/m/dev/comfyui
ExecStart=/home/m/dev/comfyui/.venv/bin/python /home/m/dev/comfyui/main.py \
    --listen 0.0.0.0 --port 8188 \
    --output-directory /home/m/dev/comfyui/output \
    --temp-directory /home/m/dev/comfyui/temp
Restart=on-failure
RestartSec=5
TimeoutStopSec=30
NoNewPrivileges=true
PrivateTmp=true
LimitNOFILE=65535

[Install]
WantedBy=multi-user.target
```

Then:

```bash
sudo systemctl daemon-reload
sudo systemctl enable --now comfyui.service
systemctl status comfyui.service
```

The service binds `0.0.0.0:8188`. Tailscale's wireguard fence is the only
auth — do **not** expose port 8188 to the public internet.

## 4. Health check

```bash
curl -fsS --max-time 5 http://mrock:8188/system_stats | jq '.devices[0]'
# expected: name "cuda:0 NVIDIA GeForce RTX 4070 Ti SUPER ...", vram_total ~16 GB
```

`imagen backends` (from a host with the ImaGen CLI installed) should also
report `flux-schnell-local: ok`.

## 5. VRAM coexistence with Ollama

mRock has 16 GB VRAM total. Ollama parks ~8 GB resident for its current
model. FLUX schnell at fp16 weights with `weight_dtype=fp8_e4m3fn` (the
default the adapter requests) needs roughly 10–12 GB peak for a 1024×1024
generation, so concurrent Ollama + FLUX on mRock will OOM.

Two practical options:

- **Stop Ollama before generating** — `sudo systemctl stop ollama` frees
  the GPU, run the generation, `sudo systemctl start ollama` afterwards.
  Adequate while we don't have many concurrent users.
- **Move Ollama off mRock** — when ImaGen is in regular use, push Ollama to
  another host so the GPU is dedicated. Tracked separately.

Both decisions live with whoever operates the box; the adapter does not try
to manage Ollama.

## 6. Smoke test (direct, without the imagen CLI)

```bash
# 1) Submit a workflow
curl -fsS --max-time 30 -X POST -H 'Content-Type: application/json' \
     -d @flux-schnell-workflow.json \
     http://mrock:8188/prompt
# returns: {"prompt_id": "...", "number": ..., "node_errors": {}}

# 2) Poll history until the prompt completes
PID=...   # from above
until curl -fsS http://mrock:8188/history/$PID | jq -e ".\"$PID\".status.completed == true" >/dev/null; do
  sleep 1
done

# 3) Pull the image
NAME=$(curl -fsS http://mrock:8188/history/$PID \
       | jq -r ".\"$PID\".outputs[\"9\"].images[0].filename")
curl -fsS "http://mrock:8188/view?filename=$NAME&type=output" -o /tmp/cat.png
file /tmp/cat.png       # PNG image data, 1024 x 1024
```

The full ImaGen smoke test is in [usage.md](usage.md) once the Go adapter
ships.

## Troubleshooting

- **`vram_free` < 6 GB in `/system_stats`**: another GPU process is holding
  memory. Usually Ollama (`sudo systemctl stop ollama`).
- **Workflow returns `node_errors` with `Required input is missing` for
  CLIPLoader**: text encoder filenames don't match step 2 — check that
  `clip_l.safetensors` and `t5xxl_fp8_e4m3fn.safetensors` are in
  `models/clip/`, not `models/text_encoders/`.
- **`Access to model … is restricted`** during a model pull: the script is
  hitting a gated mirror. Use the ungated URLs from step 2.
- **Service won't start**: check `journalctl -u comfyui --since '5 min ago'`.
  Common cause is a stale `pip` install — re-run step 1.