Trying to do this line:

/etc/glusterfs/grid-client.vol  /mnt/glusterfs-grid  glusterfs  defaults  0  0

Using this:

    mount {
        "/mnt/glusterfs-grid":
            name => "/mnt/glusterfs-grid",
            atboot => true,
            device => "/etc/glusterfs/grid-client.vol",
            ensure => mounted,
            fstype => glusterfs,
            options => defaults,
            remounts => false,
            target => "/etc/fstab"
    }