How to generate a certificate？？

[gocuntian]

How to generate a certificate file? Thank you

fixtures/tls/fabricca/ca/
ca_root-key.pem
ca_root.pem

[gocuntian]

certfiles:
- "$GOPATH/src/github.com/chainhero/heroes-service/fixtures/tls/fabricca/ca/ca_root.pem"
client:
keyfile: "$GOPATH/src/github.com/chainhero/heroes-service/fixtures/tls/fabricca/client/client_client1-key.pem"
certfile: "$GOPATH/src/github.com/chainhero/heroes-service/fixtures/tls/fabricca/client/client_client1.pem"