Importing LetsEncrypt into Java and Glassfish Server

How to install letsencrypt free ssl to glassfish 4.x server

Checking A Remote Certificate Chain With OpenSSL

Create a self-signed SSL Certificate with OpenSSL

openssl genrsa -out key.pem 2048
openssl req -new -key key.pem -out csr.pem
openssl req -x509 -days 365 -key key.pem -in csr.pem -out certificate.pem

https://startssl.com/