Gitlab runner --tls-ca-file option is a file or folder?

Hi there,
I’ve configured my Gitlab server with a self-signed certificate and a custom CA. My assumption is I therefore need to provide a CA, cert and key to my runners so they can communicate with the server.

The documentation for [[runners]] mentions a --tls-ca-file option with the description “file containing the certificates to verify the peer when using HTTPS”. The fact that ‘certificates’ is pluralized suggests to me that this should in fact be a folder containing a number of certificates (CA, cert, key I would guess). In fact the [[runners.docker]] section includes an argument --tls_cert_path with the description “when set it will use ca.pem, cert.pem and key.pem from that folder”.

So my question is, is the --tls-ca-file option for [[runners]] supposed to be a path to a folder containing certificate files? If so, should the files be named ca.pem, cert.pem and key.pem as per the [[runners.docker]] config?