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Running ComfyUI

Learn how to start, stop, and manage the ComfyUI web interface in your environments.

Prerequisites

  • Environment created — cg create my-env
  • Environment set as active — cg use my-env (or use -e flag)

Basic usage

Start ComfyUI in your active environment:

cg run

Output:

🎮 Starting ComfyUI in environment: my-env

ComfyUI then outputs its startup logs and opens on http://localhost:8188

First run

The first time you run ComfyUI in an environment, it may take a few seconds to initialize. Subsequent runs are faster.

Running in specific environment

If you don't have an active environment set:

cg -e my-env run

Or switch environments:

# Set active
cg use my-env

# Then run
cg run

Accessing ComfyUI

Once running, open your browser to:

http://localhost:8188

You should see:

  • ComfyUI's web interface
  • Default workflow loaded
  • Node library on the left
  • Canvas in the center

Stopping ComfyUI

ComfyUI runs in the foreground by default. To stop it:

Press Ctrl+C in the terminal

^C
✓ ComfyUI stopped

Running in the background

Using &

Run ComfyUI in the background:

cg run &

To stop:

# Find the process
ps aux | grep ComfyUI

# Kill it
kill <PID>

Using screen

More reliable for long-running sessions:

# Start a screen session
screen -S comfy

# Run ComfyUI
cg run

# Detach with Ctrl+A, then D

To reattach:

screen -r comfy

To stop:

# Reattach
screen -r comfy

# Press Ctrl+C
# Exit screen
exit

Using tmux

Another option for persistent sessions:

# Start tmux session
tmux new -s comfy

# Run ComfyUI
cg run

# Detach with Ctrl+B, then D

To reattach:

tmux attach -t comfy

To stop:

# Reattach
tmux attach -t comfy

# Press Ctrl+C
# Exit tmux
exit

Passing arguments to ComfyUI

ComfyGit passes all arguments after run directly to ComfyUI's main.py:

Change port

# Run on port 8080
cg run --port 8080

Access at: http://localhost:8080

Listen on all interfaces

# Allow external access
cg run --listen 0.0.0.0

Security

Only use --listen 0.0.0.0 on trusted networks. This exposes ComfyUI to your entire network.

Auto-launch browser

# Open browser automatically
cg run --auto-launch

Enable CORS

# Allow cross-origin requests
cg run --enable-cors-header

Disable GPU

# Force CPU-only execution
cg run --cpu

Useful for testing or if GPU is in use.

Multiple arguments

Combine any ComfyUI arguments:

cg run --port 8080 --listen 0.0.0.0 --auto-launch

Output:

🎮 Starting ComfyUI in environment: my-env
   Arguments: --port 8080 --listen 0.0.0.0 --auto-launch

ComfyUI arguments

For a full list of ComfyUI arguments, run: 

cg run -- --help
The -- separator tells cg to pass all remaining arguments to ComfyUI.

Running multiple environments simultaneously

You can run different environments on different ports:

# Terminal 1: production on default port
cg -e production run

# Terminal 2: testing on port 8189
cg -e testing run --port 8189

# Terminal 3: dev on port 8190
cg -e dev run --port 8190

Access each at:

  • Production: http://localhost:8188
  • Testing: http://localhost:8189
  • Dev: http://localhost:8190

Resource usage

Running multiple ComfyUI instances simultaneously uses significant GPU memory. You may need to reduce batch sizes or use CPU mode for secondary instances.

Checking logs

If ComfyUI fails to start or behaves unexpectedly:

ComfyUI output

ComfyUI prints logs directly to your terminal when run in the foreground. Look for:

  • Errors during startup — Missing dependencies, port conflicts
  • Model loading issues — Missing models, corrupt files
  • Custom node errors — Failed imports, missing packages

ComfyGit logs

For environment-level issues:

# Show recent logs
cg debug -n 50

# Show all logs
cg debug

# Follow logs in real-time
tail -f ~/comfygit/logs/comfygit.log

Common scenarios

Quick testing

# Start, test, stop
cg run
# Use ComfyUI...
# Ctrl+C when done

Long-running server

# Use screen or tmux
screen -S comfy
cg run

# Detach: Ctrl+A, D
# ComfyUI keeps running

Development workflow

# Terminal 1: Run ComfyUI
cg run

# Terminal 2: Make changes, test, commit
cg node add new-node
# Test in browser...
cg commit -m "Added new node"

Testing workflow files

# Start ComfyUI
cg run

# Open http://localhost:8188
# Load workflow from ComfyUI/user/default/workflows/
# Make changes in browser
# Save workflow
# Stop ComfyUI (Ctrl+C)

# Check status
cg status
# Will show modified workflow

# Commit if good
cg commit -m "Updated workflow"

Troubleshooting

Port already in use

Symptom: Address already in use error on port 8188

Solutions:

# Find what's using port 8188
lsof -i :8188

# Kill the process
kill <PID>

# Or use a different port
cg run --port 8189

GPU out of memory

Symptom: CUDA out of memory errors

Solutions:

# Force CPU mode
cg run --cpu

# Or close other GPU applications
# Or reduce batch size in ComfyUI
# Or use a smaller model

Custom nodes not loading

Symptom: "Failed to import custom node" in logs

Solutions:

# Stop ComfyUI (Ctrl+C)

# Repair environment
cg repair

# Restart ComfyUI
cg run

Models not found

Symptom: "Model not found" errors in ComfyUI

Solutions:

# Check model symlink
ls -la ~/comfygit/environments/my-env/ComfyUI/models

# Should show symlink to workspace models
# If not, recreate environment or check workspace init

# Sync model index
cg model index sync

# Check where ComfyUI expects models
# They should be in ~/comfygit/models/<category>/

ComfyUI crashes immediately

Symptom: ComfyUI starts then exits with error

Solutions:

# Check environment is synced
cg status

# Repair if needed
cg repair

# Check for Python dependency conflicts
cg py list

# Try running Python directly to see error
cd ~/comfygit/environments/my-env/ComfyUI
~/comfygit/environments/my-env/.venv/bin/python main.py

Can't access from another device

Symptom: Can access http://localhost:8188 but not from phone/tablet

Solutions:

# Run with listen flag
cg run --listen 0.0.0.0

# Find your machine's IP
# macOS/Linux
ifconfig | grep inet

# Then access from other device
http://<your-ip>:8188

Firewall

You may need to allow port 8188 through your firewall for external access.

Next steps

Now that ComfyUI is running:

See also