relayd and letsencrypt certificates

[Thuban]

Hello,
I can't figure how to use letsencrypt certificates with relayd. I keep
getting this error : 

    # relayd -vvv -n
    /etc/relayd.conf:33: cannot load certificates for relay tlsforward


My relayd.conf : 

    # cat /etc/relayd.conf
    table <local> { 127.0.0.1 }
    ext_ip = 192.168.1.66

    http protocol "https" {
        tcp { nodelay, sack, socket buffer 65536, backlog 100 }
        match response header set "Cache-Control" value "max-age=1814400"
        return error
        pass
        tls { no client-renegotiation, cipher-server-preference }
        tls ca key "/etc/letsencrypt/certificates/privkey.pem" password ""
        tls ca cert "/etc/letsencrypt/certificates/cert.pem"
    }


    relay "tlsforward" {
        listen on $ext_ip port 443 tls
        protocol "https"
        forward to <local> port 8443 mode loadbalance check tcp
    }



Do you see any error or have any advice?

Regards.

thuban