Yes, you just need to set the variable in the catalog using this notation ${cool_variable} and the --params would be something --params "cool_variable:cool_variable_value, ..." and in the extra_params you would get a dict {cool_variable : cool_variable_value} wich can be passed to the the TemplatedConfigLoader in the globals_dict. Whatever is passed in the globals_dict will be used to fill the catalog and will have precedence to the globals.yml which is used by default.