mcp-comfy-server

Zorba-the-buddhah/mcp-comfy-server

3.2

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A stateful Model Context Protocol (MCP) server for ComfyUI, built with Cloudflare Workers and Durable Objects.

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d# ComfyUI MCP Server

A stateful Model Context Protocol (MCP) server for ComfyUI, built with Cloudflare Workers and Durable Objects.

Features

  • Stateful Job Management: Tracks submitted workflows with persistent storage
  • Workflow Submission: Submit ComfyUI workflows with optional prompt customization
  • Job Status Tracking: Check the status of submitted jobs and retrieve results
  • Job History: View all jobs submitted in the current session
  • Health Monitoring: Check ComfyUI server connectivity

Prerequisites

  • Node.js 18+ and npm
  • Cloudflare account (for deployment)
  • Running ComfyUI instance
  • Wrangler CLI (npm install -g wrangler)

Setup

  1. Install dependencies:

    npm install

  2. Configure environment:

    • Copy .dev.vars.example to .dev.vars
    • Update COMFYUI_URL with your ComfyUI instance URL

  3. Update workflow template:

    • Edit src/mcp-do.ts and replace DEFAULT_WORKFLOW with your actual ComfyUI workflow JSON
    • Ensure the workflow has the appropriate input nodes for prompt text

Development

Run the development server:

npm run dev

The server will be available at http://localhost:8787

Quick testing with inspector:

npm run inspect      # Opens web inspector
npm run inspect:cli  # Tests tools via CLI

Testing with MCP Inspector

The MCP Inspector is the official visual testing tool for MCP servers.

Option 1: Web Inspector (UI Mode)

Best for interactive testing and debugging during development:

  1. Visit https://mcp-inspector.mcp-servers.com/
  2. Enter your server URL: http://localhost:8787/mcp (StreamableHttp transport)
  3. Click "Connect"

You can also use query parameters for initial configuration:

http://localhost:6274/?transport=streamable-http&serverUrl=http://localhost:8787/mcp

Option 2: CLI Inspector

Best for scripting, automation, and rapid development feedback loops:

# Interactive UI mode (opens browser)
npx @modelcontextprotocol/inspector http://localhost:8787/mcp

# CLI mode for programmatic access
npx @modelcontextprotocol/inspector --cli http://localhost:8787/mcp --method tools/list

# Call a specific tool
npx @modelcontextprotocol/inspector --cli http://localhost:8787/mcp --method tools/call --tool-name submitWorkflow --tool-arg prompt="beautiful sunset"

Transport Types

This server uses Streamable HTTP transport by default. The inspector also supports:

  • STDIO: For local processes
  • SSE: Legacy server-sent events (supported for backward compatibility)
  • Streamable HTTP: HTTP-based transport (default)

Available Tools to Test

  • submitWorkflow - Submit a new workflow with optional prompt
  • getJobStatus - Check the status of a submitted job
  • getJobHistory - List recent jobs from this session
  • healthCheck - Verify ComfyUI server connectivity

Inspector Configuration

The inspector supports various environment variables for configuration:

  • MCP_SERVER_REQUEST_TIMEOUT: Request timeout in milliseconds (default: 10000)
  • MCP_REQUEST_TIMEOUT_RESET_ON_PROGRESS: Reset timeout on progress notifications (default: true)
  • MCP_REQUEST_MAX_TOTAL_TIMEOUT: Maximum total timeout for requests (default: 60000)

For comprehensive inspector usage, see

Deployment

Local ComfyUI Instance

  1. Set production secrets:

    wrangler secret put COMFYUI_URL
# Enter: http://your-local-ip:8188

  2. Deploy to Cloudflare:

    npm run deploy

Cloud ComfyUI Instance (Google Cloud/AWS/etc.)

CRITICAL: Cloudflare Workers require HTTPS for external requests. ComfyUI runs on HTTP by default, so you need HTTPS termination.

Network Requirements:

  • Static IP address (required for reliable connectivity)
  • HTTPS endpoint (Cloudflare Workers cannot make HTTP requests)
  • No authentication barriers for HTTP requests

What Works:

  • ✅ Dedicated compute instances (Google Workbench, AWS EC2, etc.) with static IPs
  • ✅ VMs with proper network configuration
  • ✅ Self-hosted servers with public IPs

What Doesn't Work:

  • ❌ Dynamic IP services (Google Colab, temporary notebooks)
  • ❌ Services requiring authentication tokens for basic HTTP access
  • ❌ Cloud notebook services with proxy URLs and network restrictions
Option 1: Cloudflare Tunnel (Recommended - Free & Easy)

Quick Setup:

# On your cloud instance
curl -L https://github.com/cloudflare/cloudflare/releases/latest/download/cloudflared-linux-amd64.deb -o cloudflared.deb
sudo dpkg -i cloudflared.deb

# Login and create tunnel
cloudflared tunnel login
cloudflared tunnel create comfyui

# Start tunnel (creates HTTPS endpoint automatically)
cloudflared tunnel --url http://localhost:8188

This gives you a free HTTPS URL like: https://random-words-123.trycloudflare.com

Start ComfyUI:

python main.py --listen 0.0.0.0 --port 8188

Update secret:

wrangler secret put COMFYUI_URL
# Enter: https://your-tunnel-url.trycloudflare.com
Option 2: Custom Domain + Reverse Proxy (Permanent Solution)

If you have a domain name, use Caddy for automatic HTTPS:

# Install Caddy
sudo apt install -y debian-keyring debian-archive-keyring apt-transport-https
curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/gpg.key' | sudo gpg --dearmor -o /usr/share/keyrings/caddy-stable-archive-keyring.gpg
curl -1sLf 'https://dl.cloudsmith.io/public/caddy/stable/debian.deb.txt' | sudo tee /etc/apt/sources.list.d/caddy-stable.list
sudo apt update && sudo apt install caddy

# Configure Caddyfile
echo "comfyui.yourdomain.com {
    reverse_proxy localhost:8188
}" | sudo tee /etc/caddy/Caddyfile

sudo systemctl reload caddy
Option 3: Manual HTTPS Setup (Advanced)

If you prefer manual configuration:

  1. Static IP + Firewall:
# Google Cloud example
gcloud compute addresses create comfyui-static-ip --region=your-region
gcloud compute firewall-rules create allow-https-comfyui \
  --allow tcp:443,tcp:80 \
  --source-ranges="0.0.0.0/0" \
  --target-tags=comfyui-server
  1. Nginx + Let's Encrypt:
sudo apt install nginx certbot python3-certbot-nginx
sudo certbot --nginx -d your-domain.com

Why HTTPS is Required: Cloudflare Workers enforce security policies that block plain HTTP requests to external services. The 403 Forbidden errors you see are due to this HTTP restriction.

Available Tools

submitWorkflow

Submit a workflow to ComfyUI for processing.

  • Parameters:
    • prompt (optional): Text prompt to use in the workflow

getJobStatus

Check the status of a submitted job.

  • Parameters:
    • prompt_id: The ID returned from submitWorkflow

getJobHistory

Retrieve the list of jobs submitted in this session.

  • Parameters:
    • limit (optional): Maximum number of jobs to return (default: 10)

healthCheck

Check if ComfyUI server is accessible and healthy.

Architecture

This server follows the recommended Cloudflare MCP architecture:

  • src/index.ts: Simple router that forwards requests to the Durable Object
  • src/mcp-do.ts: Durable Object containing all MCP logic and state management
  • Uses this.state.storage for persistent job storage
  • Implements proper error handling and input validation with Zod

Security

  • All tool inputs are validated using Zod schemas
  • Environment variables are used for sensitive configuration
  • Error messages are sanitized to prevent information leakage
  • CORS is handled appropriately for browser-based clients

Development Workflow

  1. Create a feature branch from main
  2. Make changes following the existing patterns
  3. Format code: npm run format
  4. Test with MCP Inspector
  5. Commit with conventional messages (feat:, fix:, etc.)
  6. Open a pull request for review