Hi, InfluxDB doesn't seem to have an internal way to forward its logs to a file or syslog. As far as I understood, one has to get the information from STDOUT/STDERR.
The following patch allows sending the logs to syslog. It uses the logger(1) utility. It is based on what is done with sysutils/prometheus. BTW, it seems there's no "MAINTAINER" in the Makefile. Regards.
--- databases/influxdb/pkg/influxdb.rc.orig Thu Jan 11 20:27:01 2018 +++ databases/influxdb/pkg/influxdb.rc Fri Mar 29 17:12:07 2019 @@ -4,4 +4,6 @@ daemon="${TRUEPREFIX}/bin/influxd" +daemon_flags="" +daemon_priority="daemon.info" daemon_user="_influx" @@ -10,4 +12,9 @@ rc_bg=YES rc_reload=NO + +rc_start() { + ${rcexec} "${daemon} ${daemon_flags} 2>&1 | \ + logger -p ${daemon_priority} -t influxd" +} rc_cmd $1