sysutils/mtail 3.0.9_13 FreeBSD

Configuration

Options name: sysutils_mtail

USES

go:modules

Service scripts

mtail

Message after installing

To use mtail you will need to provide the service flags you want to
enable via the mtail_args setting in rc.conf. Most important is that
you need to specify a path for -progs and a comma separated list for
-logs which indicates the log files to monitor. The progs directory will
contain the .mtail files which define the rules and patterns it uses to
generate metrics from your log files. You can find examples for some
common services in /usr/local/share/examples/mtail. 

A working example for Apache might look like the following:

mkdir -p /usr/local/etc/mtail
cp /usr/local/share/examples/mtail/apache_common.mtail /usr/local/etc/mtail/

In rc.conf:
mtail_enable="YES"
mtail_args="-address 127.0.0.1 -port 3903 -progs /usr/local/etc/mtail -logs /var/log/httpd-access.log"

Now you can start the mtail service and it should begin providing the
Prometheus style metrics on http://127.0.0.1:3903/metrics.

The documentation explaining the syntax can be found in /usr/local/share/doc/mtail.
You may find examples for other common services on the internet.

It is important to ensure the mtail service user can read the log files.