$ cfssl gencsr --help
	cfssl gencsr -- generate a csr from a private key with existing CSR json specification or certificate

Usage of genkey:
        cfssl gencsr -key private_key_file [-host hostname_override] CSRJSON
        cfssl gencsr -key private_key_file [-host hostname_override] -cert certificate_file

Arguments:
        CSRJSON:    JSON file containing the request, use '-' for reading JSON from stdin

Flags:
  -key="": private key for the certificate
  -cert="": Client certificate that contains the public key
  -loglevel=1: Log level (0 = DEBUG, 5 = FATAL)

 $ cfssl version
Version: 1.3.3
Revision: dev
Runtime: go1.12.3