The Farmguardian section lists all the available health checks in the load balancer, a short description of everyone and the farms where they’re applied.
Farmguardian is used for advanced monitoring state of backends. When a problem is detected by Farm Guardian automatically disables the real server and will be marked as blacklisted.

The health checks could be both pre-configured or custom. The two types of checks can be identified through the action column, the checks with the eye icon are pre-configured and the checks with the pencil and trash icon are customs checks.

The information in the Farm Guardian table includes:
NAME. Identification name of the Farm Guardian check.
DESCRIPTION. This field can contain some description about a certain health check.
COMMAND. Check command and parameters to be executed on every interval against every backend.
FARMS. Farms and services that use a certain check.
ACTIONS. The allowed actions are:

• EDIT. (Pencil icon) It redirects to the configure screen of that Farmguardian check. Only for custom farmguardian checks.
• SHOW. (Eye icon) It redirects to the configure screen of that Farmguardian check, but its global settings are not editable. Only for pre-configured farmguardian checks.
• DELETE. It deletes that Farmguardian check. If the check has configured some farm/service, then a notification will ask you if force the delete. Only for custom farmguardian checks.

Pre-configured health checks

The available built-in health checks that could be used for your farms are the following:

check_tcp: Send TCP connection to backend.
check_http: Send HTTP request to backend and expect a 200 OK response with a timeout of 5 secs.
check_https: Send HTTPS request to backend and expect a 200 OK response with a timeout of 5 secs.
check_http_response_string: Send HTTP request to backend, expect a 200 OK response and a given string in the HTML with a timeout of 5 secs. Change string by value to find in the response.
check_https_response_string: Send HTTP request to backend and expect a response of 200 OK and a given string in the HTML with a timeout of 5 secs. Change string by value to find in the response.
check_ldap: Send LDAP query to backend and expect LDAP bind with a timeout of 5 secs. Change -b (base search), -D (user to bind), -P (user password).
check_ldaps: Send LDAPS query to backend and expect LDAP bind with a timeout of 5 secs. Change -b (base search), -D (user to bind), -P (user password).
check_smtp: Send SMTP connection to backend and expect an SMTP response OK with a timeout of 5 secs.
check_imap: Send IMAP connection to backend and expect an IMAP response OK with a timeout of 5 secs.
check_pop: Send POP connection to backend and expect a POP response OK with a timeout of 5 secs.
check_udp: Send UDP connection to backend and check if the port is opened.
check_ping: Send 2 ICMP packets and check that the 100% reaches the host.
check_common: Check the folder usr/lib/nagios/plugins, which includes more checks, get more info about the health check with –help.

Next step, create a custom Farmguardian check.