postgres.nix

  fileSystems = {
    "/var/lib/postgresql" = {
      device = "/dev/rbd0";
      fsType = "xfs";
      options = ["rw" "noauto" "x-systemd.automount"];
    };
  };

  systemd.automounts = [{
    where = "/var/lib/postgresql";
    requiredBy = ["postgresql.service"];
    requires = ["network-online.target" "rbd0.service"];
  }];

  systemd.services.rbd0 = {
    description = "RADOS block device for PostgreSQL";
    requires = ["network-online.target"];
    conflicts = ["shutdown.target"];

    serviceConfig = {
      Type = "oneshot";
      RemainAfterExit = "yes";

      ExecStart = "${pkgs.ceph-client}/bin/rbd --user postgres map postgres/data";
      ExecStop = "${pkgs.ceph-client}/bin/rbd unmap /dev/rbd0";
    };
  };