Example config to pull down Cisco Wireless Controller/AP stats into telegraf by SNMP
Some different metrics more specific to AP health like CAPWAP uptime, AP uptime, and CPU/Memory are in the SNMPv3 example.
Tested with Telegraf 1.1.0 (Will not work in earlier versions as the SNMP plugin does not support oid_index_suffix
Make sure you've installed Cisco MIBs into a folder which is readable by snmptranslate (or define the mibdirs variable as descriped in the SNMP plugin docs at https://github.com/influxdata/telegraf/tree/master/plugins/inputs/snmp )
Copy the config file to telegraf.d/ in your telegraf config dir (which is /etc/telegraf under Ubuntu, at least).
Define your WLCs and SNMP communities in the config file - make sure you have outputs defined in telegraf, and data should start to be collected
You probably want at least 20 seconds between collection attempts, as SNMP isn't the fastest.
I'd rather be doing this with NETCONF and YANG which slowly seems to be making its way into IOS-XE, but it's not available in the AirOS code - hopefully this will change soon.