Alertmanager install

Install

pkg install alertmanager  # FreeBSD
pacman -S alertmanager    # Archlinux

You'll also need to enable/start the service.

Service

FreeBSD

In FreeBSD-13.0, the service bundled with FreeBSD doesn't always log to it's logfile, and isn't rotated.
I combined prometheus's service to create a replacement (so both prometheus and alertmanager log to the syslog.

#!/bin/sh

# PROVIDE: alertmanager
# REQUIRE: LOGIN
# KEYWORD: shutdown
#
#
# Add the following lines to /etc/rc.conf.local or /etc/rc.conf
# to enable this service:
#
# alertmanager_enable (bool):     Set to NO by default
#                               Set it to YES to enable alertmanager
# alertmanager_user (string):     Set user to run alertmanager
#                               Default is "alertmanager"
# alertmanager_group (string):    Set group to run alertmanager
#                               Default is "alertmanager"
# alertmanager_config (string):   The configuration file
#                               Default is "/usr/local/etc/alertmanager/alertmanager.yml"
# alertmanager_data_dir (string):   The configuration file
#                               Default is "/var/db/alertmanager"
# alertmanager_args (string):     Set additional command line arguments
#                               Default is ""
# alertmanager_syslog_output_enable (bool)
#     Set it to NO to disable syslog output
#     Set to YES by default
# alertmanager_syslog_output_tag (str)
#     Set syslog tag if syslog enabled
#     Default is "alertmanager"
# alertmanager_syslog_output_priority (string)
#     Set syslog priority if syslog enabled
#     Default is "info"
# alertmanager_syslog_output_facility (string)
#     Set syslog facility if syslog enabled
#     Default is "daemon"

. /etc/rc.subr

name=alertmanager
rcvar=alertmanager_enable

load_rc_config $name

: ${alertmanager_enable:="NO"}
: ${alertmanager_user:="alertmanager"}
: ${alertmanager_group:="alertmanager"}
: ${alertmanager_config:="/usr/local/etc/alertmanager/alertmanager.yml"}
: ${alertmanager_data_dir:="/var/db/alertmanager"}
: ${alertmanager_syslog_output_enable:="YES"}
: ${alertmanager_loglevel:="info"}
: ${alertmanager_args:=""}


if checkyesno alertmanager_syslog_output_enable; then
	if [ -n "${alertmanager_syslog_output_tag}" ]; then
		alertmanager_syslog_output_flags="-T ${alertmanager_syslog_output_tag}"
	else
		alertmanager_syslog_output_flags="-T ${name}"
	fi
	if [ -n "${alertmanager_syslog_output_priority}" ]; then
		alertmanager_syslog_output_flags="${alertmanager_syslog_output_flags} -s ${alertmanager_syslog_output_priority}"
	fi
	if [ -n "${alertmanager_syslog_output_facility}" ]; then
		alertmanager_syslog_output_flags="${alertmanager_syslog_output_flags} -l ${alertmanager_syslog_output_facility}"
	fi
fi


pidfile=/var/run/alertmanager.pid
required_files="${alertmanager_config}"
command="/usr/sbin/daemon"
procname="/usr/local/bin/alertmanager"
sig_reload=HUP
extra_commands="reload"
command_args="-f ${alertmanager_syslog_output_flags} -p ${pidfile} -t ${name} \
	/usr/bin/env ${procname} \
        --config.file=${alertmanager_config} \
	--log.level=${alertmanager_loglevel} \
        --storage.path=${alertmanager_data_dir} \
        ${alertmanager_args}"

start_precmd="alertmanager_start_precmd"

alertmanager_start_precmd()
{
    if [ ! -e ${pidfile} ]; then
        install -o ${alertmanager_user} -g ${alertmanager_group} /dev/null ${pidfile};
    fi
    if [ ! -d ${alertmanager_data_dir} ]; then
        install -d -o ${alertmanager_user} -g ${alertmanager_group} -m 750 ${alertmanager_data_dir}
    fi
}

load_rc_config $name
run_rc_command "$1"