Nightwatch + webdriver-manager

yarn start to start selenium server
yarn stop to shudwon selenium server

Headless Selenium Testing on Ubuntu Server

Install Xvfb (X windows virtual framebuffer)
sudo apt-get install xvfb
Add following script into package.json

xvfb-run --server-args=\"-screen 0 1920x1080x24\" webdriver-manager start

Remote Control Xvfb Virtual Desktop

Install x11vnc
sudo apt-get install x11vnc

Host VNC Server

x11vnc -listen 172.30.0.71 -rfbport 5900 -noipv6 -passwd password -display :0 -forever

Use VNC software connect to server.
For example, TigerVNC for Windows. http://www.tightvnc.com/