Netplan is a utility for easily configuring networking on a linux system. You simply create a YAML description of the required network interfaces and what each should be configured to do. From this description Netplan will generate all the necessary configuration for your chosen renderer tool.
Netplan reads network configuration from /etc/netplan/*.yaml which are written by administrators, installers, cloud image instantiations, or other OS deployments. During early boot it then generates back-end specific configuration files in /run to hand off control of devices to a particular networking daemon.
You can find out more about Netplan on the Ubuntu Netplan wiki page or the Netplan website.
