Monitoring services on your server is crucial for ensuring reliability and rapid recovery from downtime.
Monit is a simple, lightweight tool perfect for monitoring and managing services automatically.
I personally use it and adjust this general config file to monitor the service i want per server, is lite weight and works with enhance.

How to Setup

Step 1: Install Monit

For Debian/Ubuntu:

sudo apt update
sudo apt install monit

Step 2: Basic Monit Configuration

Edit Monit's config file:

sudo nano /etc/monit/monitrc

Enable the web interface (optional):

set httpd port 2812 and
    use address 0.0.0.0
    allow admin:monit

Step 3: Configuring Monit to Monitor Essential Services

Add the following to /etc/monit/monitrc:

#SSH

check program sshd with path "/bin/systemctl is-active --quiet ssh"
    if status != 0 then exec "/bin/systemctl restart ssh"
    if 5 restarts within 5 cycles then timeout

#Cron

check program cron with path "/bin/systemctl is-active --quiet cron"
    if status != 0 then exec "/bin/systemctl restart cron"
    if 5 restarts within 5 cycles then timeout

#Rspamd

check program rspamd with path "/bin/systemctl is-active --quiet rspamd"
    if status != 0 then exec "/bin/systemctl restart rspamd"
    if 5 restarts within 5 cycles then timeout

#Postfix

check program postfix with path "/bin/systemctl is-active --quiet postfix"
    if status != 0 then exec "/bin/systemctl restart postfix"
    if 5 restarts within 5 cycles then timeout

#Dovecot

check program dovecot with path "/bin/systemctl is-active --quiet dovecot"
    if status != 0 then exec "/bin/systemctl restart dovecot"
    if 5 restarts within 5 cycles then timeout

#Pure-FTP

check program pure-ftpd with path "/bin/systemctl is-active --quiet pure-ftpd"
    if status != 0 then exec "/bin/systemctl restart pure-ftpd"
    if 5 restarts within 5 cycles then timeout

#LiteSpeed Web Server (LSWS)

check program lsws with path "/bin/systemctl is-active --quiet lsws"
    if status != 0 then exec "/bin/systemctl restart lsws"
    if 5 restarts within 5 cycles then timeout

#Nginx or Apache (choose one and uncomment)

# Nginx
#check program nginx with path "/bin/systemctl is-active --quiet nginx"
#    if status != 0 then exec "/bin/systemctl restart nginx"
#    if 5 restarts within 5 cycles then timeout

# Apache
#check program apache2 with path "/bin/systemctl is-active --quiet apache2"
#    if status != 0 then exec "/bin/systemctl restart apache2"
#    if 5 restarts within 5 cycles then timeout


#Server load
check system localhost
    if loadavg (1min) > 8 then alert

Step 5: Verify Status

Check status easily with:

sudo monit status

Alerts

Set up email alerts in your monitrc to receive notifications for service restarts and failures:

set mailserver smtp.example.com port 587
    username "user@example.com" password "yourpassword"
    using tls

set alert admin@example.com

Additional Examples

# Alert on high RAM usage
#check system localhost
#    if memory usage > 90% then alert

# Alert on disk usage
#check filesystem rootfs with path /
#    if space usage > 80% then alert

# Alert on inode usage
#check filesystem rootfs with path /
#    if inode usage > 90% then alert

Now Monit will automatically monitor, restart services as needed, and alert you via email if anything goes wrong, ensuring your server remains stable and reliable