use widget.watch

spotify-widget-v4/spotify.lua

@@ -1,18 +1,17 @@
 local wibox = require("wibox")
 local awful = require("awful")
+local watch = require("awful.widget.watch")
 
 spotify_widget = wibox.widget.textbox()
 spotify_widget:set_font('Play 9')
 
-function updateSpotifyWidget(widget)
-    awful.spawn.easy_async([[bash -c 'sp current-oneline']],
-    function(stdout, stderr, reason, exit_code)
-        widget:set_text(stdout)
-    end)
-end
+-- optional icon, could be replaced by spotfiy logo (https://developer.spotify.com/design/)
+spotify_icon = wibox.widget.imagebox()
+spotify_icon:set_image("/usr/share/icons/Arc-Icons/places/symbolic/folder-music-symbolic.svg")
 
-spotify_timer = timer ({timeout = 10})
-spotify_timer:connect_signal ("timeout", function() updateSpotifyWidget(spotify_widget) end) 
-spotify_timer:start()
-
-spotify_timer:emit_signal("timeout")
+watch(
+    "sp current-oneline", 1,
+    function(widget, stdout, stderr, exitreason, exitcode)
+        spotify_widget:set_text(stdout)
+    end
+)