local progress_bar = wibox.widget {
        max_value     = 100,
        value         = 50,
        forced_height = 0.5,
        forced_width  = 100,
        widget        = wibox.widget.progressbar,
        shape         = gears.shape.rounded_bar,
        margins       = {
            top = 5,
            bottom = 5,
        },
    }

local textbox = wibox.widget {
        text   = '50%',
        align = 'center',
        widget = wibox.widget.textbox,
    }

volume_widget = wibox.widget {
    progress_bar,
    textbox,
    layout = wibox.layout.stack
}