It is quite common to have some monitoring tools perform health checks on haproxy. Sometimes it will be a layer 3 load-balancer such as LVS or any commercial load-balancer, and sometimes it will simply be a more complete
monitoring system such as Nagios. When the tests are very frequent, users often ask how to disable logging for those checks. There are three possibilities :
- if connections come from everywhere and are just TCP probes, it is often desired to simply disable logging of connections without data exchange, by setting “option dontlognull” in the frontend. It also disables logging of port scans, which may or may not be desired.
- if the connection come from a known source network, use “monitor-net” to declare this network as monitoring only. Any host in this network will then only be able to perform health checks, and their requests will not be logged. This is generally appropriate to designate a list of equipment such as other load-balancers.
- if the tests are performed on a known URI, use “monitor-uri” to declare this URI as dedicated to monitoring. Any host sending this request will only get the result of a health-check, and the request will not be logged.