code location

https://github.com/apache/incubator-apisix/blob/master/apisix/balancer.lua#L64
https://github.com/apache/incubator-apisix/blob/master/apisix/balancer.lua#L95
https://github.com/apache/incubator-apisix/blob/master/apisix/balancer.lua#L198
https://github.com/apache/incubator-apisix/blob/master/apisix/balancer.lua#L201
https://github.com/apache/incubator-apisix/blob/master/apisix/balancer.lua#L206

refer to the health check configuration:
https://github.com/apache/incubator-apisix/blob/master/doc/health-check.md
host should be from checks.active.host instead of checks.host