As @andreas-doehler said. To fix the WATO plugin, go to ~/local/share/check_mk/web/plugins/wato and edit the file rocketchat-notification.py. Locate the following statement near the bottom of the file:
default_value = "http://" + socket.gethostname() + "/" + (
defaults.omd_site and defaults.omd_site + "/" or "") + "check_mk/",
Replace defaults.omd_site with config.omd_site() so that it reads
default_value = "http://" + socket.gethostname() + "/" + (
config.omd_site() and config.omd_site() + "/" or "") + "check_mk/",
You may also try
default_value = local_site_url,
local_site_url is a function defined in ~/lib/python/cmk/gui/plugins/wato/notifications.py. I’m not sure if it is available from within the local plugins.
I cannot tell about
though.