Citrix has some helpful documentation online about configuring remote syslog support for XenServer using the XenCenter GUI. However, if you need to do this via configuration management or scripts, using a GUI isn’t an option.

Getting it done via the command line is relatively easy:

HOSTUUID=`xe host-list --minimal`
SYSLOGHOST=syslog.example.com
xe host-param-set uuid=${HOSTUUID} logging:syslog_destination=${SYSLOGHOST}
xe host-syslog-reconfigure host-uuid=${HOSTUUID}

Removing the configuration and going back to only local logging is easy as well:

HOSTUUID=`xe host-list --minimal`
xe host-param-clear uuid=${HOSTUUID} param-name=logging
xe host-syslog-reconfigure host-uuid=${HOSTUUID}