It would be nice to use the same config file as Puppet Enterprise's PuppetDB CLI, e.g.:
{
"puppetdb": {
"server_urls": "https://<PUPPETDB_HOST>:8081",
"cacert": "/etc/puppetlabs/puppet/ssl/certs/ca.pem",
"cert": "/etc/puppetlabs/puppet/ssl/certs/<WORKSTATION_HOST>.pem",
"key": "/etc/puppetlabs/puppet/ssl/private_keys/<WORKSTATION_HOST>.pem"
}
}