Awesome wm Unagi transparency for bars

Awesome is a window manager that lets you setup the environment through a programming language(Lua) .I installed Unagi(compositing window manager) and I can make firefox transparent .For example this awful.rules:

{rule = {class = "Firefox"}, 
 properties = {opacity = 0.8} }

How would you make the awful.wibox transparent by setting up the rules? or is there a different way of making the awful.wibox transparent?

wmbar = awful.wibox({ position = "right", screen = 1 })
wmbar.widgets = { 
    widget1,
    widget2,
    layout = awful.widget.layout.vertical.flex }

Solution

Rules of awesome's window matching (for setting opacity) relies on window properties, which you can see using xprop. wibox, including promptbox, layoutbox, taglist and tasklist renders on panel window. You can set opacity of any window on x-server (including awesome panel) independently of your window manager using transset-df (pacman -S transset-df for arch), for example. But you can't change opacity of only fragment of external window, and awesome doesn't support transparency by itself - it fully relies on underlying composite managers.