nfacctd-snmp-check

This is a short C++ programm that should be used with keepalived MISC_CHECK check to confirm that nfacctd service is running on specific host.

What's going on here?

Check process has tree components:

• Local check proc_check - On the nfacct server
• Extended snmpd OIDS (example in snmpd.conf) - On the nfacct server
• nfacctd_check - On the loadbalancer (KeepaliveD)

Local check (proc_check) runs the simple bash command that counts number of proccesses that match a given argument (nfacctd). Output from this check is bound via SNMPD config to a custom (extended) OID that is polled by nfacctd_check. Example part of snmpd.conf:

extend nfacctd /usr/local/sbin/proc_check nfacctd

If the number of proccesses is zero, nfacctd server should be considered offline by the loadbalancer (KeepaliveD). This is done by KeepaliveD MISC_CHECK check. Example part of the keepalived.conf config for a real server using this check:

real_server <ip_address> <port> {
    weight 1
    MISC_CHECK {
      misc_path "/usr/local/sbin/nfacctd_check <nfacctd_server_hostname>"
    }
  }
}

Since nfacctd_check exits with error if there's no running nfacctd proccess on <nfacctd_server_hostname> (or if there is some kind of SNMP error), the check will fail in those cases and exclude the real server from loadbalancing.

This could be easily changed to check for any running proccess by changing the argument passed to proc_check in snmpd config.