The below was guided by the Eric Urban's excellent tutorial at http://www.hydrogen18.com/blog/your-own-pki-tls-golang.html
git clone https://github.com/OpenVPN/easy-rsa.git example-ca
cd example-ca/easyrsa3
./easyrsa init-pki
...
./easyrsa build-ca
...
./easyrsa build-server-full localhost nopass
...
./easyrsa build-client-full 'client0' nopass
...