Relevant part of /etc/nixos/configuration.nix

  services.zrepl = {
    enable = true;
    config = ''
      jobs:
        - type: source
          name: work-desktop
          serve:
            type: tcp
            listen: "0.0.0.0:7070"
            clients: {
              "127.0.0.1" : "server0"
            }
          filesystems: {
            "rpool/vols/desktop" : true,
            "rpool/vols/dovecot" : true
          }
          snapshotting:
            type: periodic
            prefix: zrepl_
            interval: 5m
      global:
        logging:
        - type: "stdout"
          level: "debug"
          format: "human"
   '';
  };