vLLM Simple Deployment

A simple skill to quickly install vLLM, start a server, and validate the OpenAI-compatible API.

What this skill does

This skill provides a streamlined workflow to:

• Detect hardware backend (NVIDIA CUDA, AMD ROCm, Google TPU, or CPU)
• Install vLLM with appropriate backend support
• Start the vLLM server with configurable model and port
• Test the OpenAI-compatible API endpoint
• Validate the deployment is working correctly
• Support virtual environment isolation

Prerequisites

• Python 3.10+
• GPU (NVIDIA CUDA, AMD ROCm) (recommended) or TPU or CPU
• pip or uv package manager
• curl (for API testing)
• Virtual environment (optional but recommended)

Usage

Create a venv

If user did not specify the venv path or asked to deploy in the current environment, create a venv using uv with python 3.12 in the current folder. If uv not found, make a folder in this path and use python to create a virtual environment.

Run the complete workflow (suggested)

If user did not specify the venv path, model, or port, use default options:

# Default deployment options (--venv "." --model "Qwen/Qwen2.5-1.5B-Instruct" --port 8000 --gpu_memory_utilization 0.8)
scripts/quickstart.sh

Or with custom options:

# Use custom virtual environment
scripts/quickstart.sh --venv /path/to/venv

# Use custom model and port
scripts/quickstart.sh --model "Qwen/Qwen2.5-1.5B-Instruct" --port 8000

# Use custom GPU memory utilization
scripts/quickstart.sh --gpu_memory_utilization 0.6

# Combine all options
scripts/quickstart.sh --venv /path/to/venv --model "Qwen/Qwen2.5-1.5B-Instruct" --port 8000 --gpu_memory_utilization 0.8

This will:

1. Activate the virtual environment (if specified)
2. Detect hardware backend (CUDA/ROCm/TPU/CPU)
3. Install vLLM with appropriate backend support
4. Start the vLLM server in the background
5. Wait for the server to be ready
6. Test the API with a sample request
7. Display the server status

Run individual commands (for step-by-step usage or troubleshooting)

Install vLLM:

scripts/quickstart.sh install
# Or with virtual environment
scripts/quickstart.sh install --venv /path/to/venv

Start the server:

scripts/quickstart.sh start
# Or with custom options
scripts/quickstart.sh start --venv /path/to/venv --model "Qwen/Qwen2.5-1.5B-Instruct" --port 8000 --gpu_memory_utilization 0.8

Test the API:

scripts/quickstart.sh test
# Or with custom port
scripts/quickstart.sh test --port 8000

Stop the server:

scripts/quickstart.sh stop
# Or with virtual environment
scripts/quickstart.sh stop --venv /path/to/venv

Check server status:

scripts/quickstart.sh status

Restart the server:

scripts/quickstart.sh restart
# Or with custom options
scripts/quickstart.sh restart --venv /path/to/venv --port 8000 --gpu_memory_utilization 0.8

Configuration

The script supports the following command-line options:

scripts/quickstart.sh [command] [OPTIONS]

Commands:
  install  - Install vLLM and dependencies
  start    - Start the vLLM server
  stop     - Stop the vLLM server
  test     - Test the OpenAI-compatible API
  status   - Show server status
  restart  - Restart the server
  all      - Run complete workflow (default)

Options:
  --model MODEL                 Model to use (default: Qwen/Qwen2.5-1.5B-Instruct)
  --port PORT                   Port to run server on (default: 8000)
  --venv VENV_PATH              Virtual environment path (default: .)
  --gpu_memory_utilization VRAM GPU memory utilization (default: 0.8)

Hardware Backend Detection

The script automatically detects your hardware and installs the appropriate vLLM version:

• NVIDIA CUDA: Detected via nvidia-smi command
• AMD ROCm: Detected via /dev/kfd and /dev/dri devices
• Google TPU: Detected via TPU_NAME environment variable or gcloud command
• CPU: Fallback if no GPU/TPU detected

For Google TPU, the script installs vllm-tpu instead of the standard vllm package.

API Testing

The test script sends a simple chat completion request:

curl http://localhost:8000/v1/chat/completions \
  -H "Content-Type: application/json" \
  -d '{
    "model": "Qwen/Qwen2.5-1.5B-Instruct",
    "messages": [{"role": "user", "content": "Say hello!"}],
    "max_tokens": 50
  }'

Troubleshooting

Virtual environment not found:

• Ensure the path provided with --venv exists and is a valid virtual environment
• Check that the activation script exists (bin/activate on Linux/macOS or Scripts/activate on Windows)
• Check and install uv, and create a new virtual environment with uv: uv venv /path/to/venv (suggested); or with pip: python3 -m venv /path/to/venv

Server won't start:

• Check if the port is already in use: lsof -i :8000
• Verify GPU availability: nvidia-smi (for NVIDIA) or rocm-smi (for AMD)
• Check vLLM installation: python -c "import vllm; print(vllm.__version__)"
• Review server logs at $VENV_PATH/tmp/vllm-server.log

API returns errors:

• Wait a few seconds for the model to load
• Check server logs: cat $VENV_PATH/tmp/vllm-server.log
• Verify the server is running: scripts/quickstart.sh status

Out of memory:

• Use a smaller model (e.g., Qwen2.5-0.5B-Instruct)
• Reduce --gpu-memory-utilization parameter
• Close other GPU-intensive applications

Wrong backend detected:

• For NVIDIA: Ensure nvidia-smi is in your PATH
• For AMD: Check that ROCm drivers are properly installed
• For TPU: Set TPU_NAME environment variable or install gcloud

Notes

• The server runs in the background and logs to $VENV_PATH/tmp/vllm-server.log
• The PID is stored in $VENV_PATH/tmp/vllm-server.pid for easy management
• First run will download the model (~3GB for Qwen2.5-1.5B-Instruct)
• Subsequent runs will use the cached model
• The script automatically detects and uses uv if available, otherwise falls back to pip
• Virtual environment support allows isolation from system Python packages
• Arguments can be specified in any order (e.g., scripts/quickstart.sh --port 8080 start --venv /path/to/venv)