Run Cloudflare Tunnel Client (formerly Argo Tunnel) on your JF.
cloudflared is tunneling daemon that proxies traffic from the Cloudflare network to your origins. This daemon sits between Cloudflare network and your origin (e.g. a webserver). Cloudflare attracts client requests and sends them to you via this daemon, without requiring you to poke holes on your firewall --- your origin can remain as closed as possible.
Extensive documentation can be found in the Cloudflare Tunnel section of the Cloudflare Docs.