ComfyUI on Modal (UI + Headless + Ollama)

This repo deploys CPU-only ComfyUI on Modal for multi-user SaaS use cases.

You can run:

• UI mode (browser) to build/test workflows
• Headless mode (API) to execute workflows for users

What you get

• A headless SaaS endpoint that accepts { user_id, ollama_url, workflow_json }
  • Injects ollama_url into OllamaConnectivity* nodes (from stavsap/comfyui-ollama)
  • Runs the workflow via ComfyUI /prompt + /history
  • Copies outputs into a persistent Modal Volume mounted at /results
  • Returns result_path + stored_paths
• Persistent volumes for models and ComfyUI user state (mounted under /persist/* and symlinked into ComfyUI)
• ComfyUI is started lazily (only when run is called) to minimize idle cost.
• Optional browser UI for workflow creation/testing

Deploy

Prereqs:

• Python installed locally
• Modal CLI set up (py -m pip install modal then py -m modal setup)

Deploy the unified app (recommended):

py -m modal deploy modal_comfyui.py

Modal prints two endpoints under the same app:

• ...-ui.modal.run (ComfyUI browser UI)
• ...-comfyrunner-run.modal.run (your SaaS runner endpoint)

Tip: keep the endpoint private and set COMFY_RUN_TOKEN in Modal, then send Authorization: Bearer <token>.

Cost note (important)

If you leave the UI tab open, it keeps a WebSocket connection and the container may stay up (cost money). Close the tab when you’re done. To force it down immediately:

py -m modal app stop comfyui

This app is CPU-only: we never request GPU resources and ComfyUI starts with --cpu.

SaaS endpoint request

POST JSON:

{
  "user_id": "user_123",
  "ollama_url": "https://<reachable-ollama-url>",
  "workflow_json": { "1": { "class_type": "...", "inputs": {} } }
}

Response includes:

• result_path: a path under the /results volume like user_123/<job_id>/output.mp4
• stored_paths: all output files copied to the volume

POST to the runner endpoint URL printed by Modal.

Legacy (older deployments)

If you previously deployed these, they still work but are no longer recommended:

• modal_comfyui_headless.py (app: comfyui-headless)
• modal_comfyui_ui.py (app: comfyui-ui)