The official way of Cisco to backup a configuration from a Cisco Wireless Controller is to buy and implement Cisco Prime. I solved it my way: You can use solarwinds CatTools to send commands to specific devices, so I configured a job to connect to the WLC via SSH to instruct the WLC pushing the configuration to a TFTP server:
transfer upload mode tftp
transfer upload datatype config
transfer upload filename WLC-Config-Backup_%DateISO%.txt
transfer upload path .
transfer upload serverip 10.20.30.5
transfer upload start
the WLC will warn you that the configuration file encryption is disabled and will ask you to do that. Solarwinds CatTools will also answer the questions with Y or Yes. After this the WLC will push the config to your tftp directory. The variable %DateISO% automatically fills out the date of the file. The Freeware version is limited to 5 devices and 5 scheduled activities.
To show the configuration directly you can use the following command:
show running-config commands