Grafana allow to use HTTPS - TLS by configurations at grafana.ini file. The two most important are the addition of the certificate file and certificate key:
# https certs & key file
cert_file = /etc/.../my)certificate.pem
cert_key = /etc/.../my_key.key
Our server (other services on our sever) use a configuration TSL structure base on certificate-key-chain file. How to add this last one (certificate chain file) to grafana.ini configuration?