Quick, dirty, no changes in rigs configs needed — http gathering:

1. Check your rig web-interface availability from zabbix-agent host https://rig.ip.address:3333/
2. Make script to return hashrate from web page
wget -nv -q -O - http://$1:3333 |grep -oP '(?<=result).*?(?=;)'|awk '{print $NF}'|sed -e 's/^"//'
3. Add this script into /etc/zabbix/zabbix_agentd.conf as
and restart zabbix-agent service
4. Check either by
zabbix_agentd -t getrighashrate[rig.ip.address]
zabbix_get -s -k getrighashrate[rig.ip.address]
5. Add items into Zabbix into zabbix-agent host and multiply values by 1000. Add graphs into your fav dashboard

Quick, dirty, snmp and logs-involved:

1. Install and run snmpd at every rig
2. At every rig add script to return current logged hashrate:
tail -n 200 /var/log/miner/claymore/lastrun_noappend.log |grep "ETH - Total Speed"|tail -n1|awk '{print $7}'
3. Add this script into /etc/snmp/snmpd.conf as
extend hashrate /path/to/snmp.script
and check for security at extension table
view systemonly included .
and restart snmpd service
4. Check this with
snmpget -c public -v2c localhost .
5. Make Zabbix template with snmpv2 item with your fav {$SNMP_COMMUNITY} and apply this to every rig in Zabbix

Additional чтиво:
https://bitcointalk.org/index.php?topic=3959954.0 https://www.ekzorchik.ru/2017/05/monitoring-the-temperature-of-the-raspberry-board/ https://www.ekzorchik.ru/2016/06/monitoring-the-weather-by-zabbix/