I'm trying to set up open vpn latest version on CentOS 7 following this tutorial https://www.hugeserver.com/kb/how-to-config-openvpn-linux-server/
The problem was there was no "vars" file to edit.
I checked every folder in easy-rsa including 3, 3.0, 3.0.3 and didn't find any "vars" file inside them.
Looks like in three this stuff changed. Tested this out and got it to work with openvpn so I believe what your looking for is...
./easyrsa init-pki
./easyrsa build-ca
./easyrsa gen-req server nopass
./easyrsa sign-req server server
openssl dhparam -out dh2048.pem 2048
Some more reference on this.... https://community.openvpn.net/openvpn/wiki/EasyRSA3-OpenVPN-Howto