This is a dockerized version of https://github.com/cloudflare/cfssl.
$ docker run -p 8888:8888 cbeer/cfssl
$ cfssl gencert -remote="localhost:8888" www.example.com csr.json
A self-signed root CA is provided out-of-the-box for demonstration purposes. To provide your own configuration, you can mount a volume containing, e.g.:
ca.pem
ca_key.pem
$ docker run -v /path/to/my/cfssl-data:/etc/cfssl -p 8888:8888 cbeer/cfssl