monitrc

# $ sudo apt install monit
# $ sudo monit
# $ sudo systemctl enable monit // enable autostart
# $ sudo service monit reload
# $ sudo monit -t
# $ sudo monit validate
# $ sudo systemctl status monit
# $ sudo cat /var/log/monit.log

# $ ssh -NL 2812:localhost:2812 deployer@IP
# http://localhost:2812/
# admin:monit

# /etc/monit/monitrc

set daemon 120   # check services at 2-minute intervals
  with start delay 240   # optional: delay the first check by 4-minutes

set log /var/log/monit.log
set idfile /var/lib/monit/id
set statefile /var/lib/monit/state

set mailserver smtp.gmail.com port 465
  username "your@gmail.com" password "PASSWORD"
  using tlsv1
  with timeout 30 seconds

set eventqueue
  basedir /var/lib/monit/events # set the base directory where events will be stored
  slots 100                     # optionally limit the queue size

set mail-format { from: your@gmail.com }

set alert other@gmail.com   # receive all alerts

set httpd port 2812 and
  use address localhost  # only accept connection from localhost
  allow localhost         # allow localhost to connect to the server and
  allow admin:monit       # require user 'admin' with password 'monit'

check system $HOST
  if loadavg (1min) > 4 then alert
  if loadavg (5min) > 2 then alert
  if cpu usage > 95% for 10 cycles then alert
  if memory usage > 75% then alert
  if swap usage > 25% then alert

check process nginx with pidfile /var/run/nginx.pid
  start program = "/usr/sbin/service nginx start" with timeout 60 seconds
  stop program  = "/usr/sbin/service nginx stop"
  if failed port 443 protocol https request /version with content = "version" with timeout 7 seconds then alert

check host api with address api.DOMAIN.COM
  if failed port 80 protocol http then alert
  if failed port 443 protocol https status = 200 and request /path with content = "text" and certificate valid > 7 days then alert

check process mysql with pidfile /run/mysqld/mysqld.pid
  start program = "/usr/sbin/service mysql start" with timeout 60 seconds
  stop program  = "/usr/sbin/service mysql stop"
  if failed unixsocket /var/run/mysqld/mysqld.sock then restart

check filesystem datafs with path /dev/sda1
  if space usage > 80% for 5 times within 15 cycles then alert
  if space usage > 99% then stop
  if read rate > 1 MB/s for 5 cycles then alert
  if read rate > 500 operations/s for 5 cycles then alert
  if write rate > 1 MB/s for 5 cycles then alert
  if write rate > 500 operations/s for 5 cycles then alert

check host myserver with address localhost
  if failed ping then alert
  if failed port 3306 protocol mysql with timeout 15 seconds then alert

check network public with interface ens3
  if failed link then alert
  if changed link then alert
  if saturation > 90% then alert
  if download > 10 MB/s then alert
  if total uploaded > 1 GB in last hour then alert

include /etc/monit/conf.d/*
include /etc/monit/conf-enabled/*