How to install Monit Monitoring Tool on Arch Linux

Monit is a free, open-source, lightweight monitoring tool used to manage and monitor services on Linux operating systems. Monit allows you to check the status of processes, files, directories, checksums, permissions, and filesystems via the command line interface. If something is wrong, Monit can notify you instantly via email. It has the ability to automatically start a process if it’s not running, restart one if it’s not responding, and stop a process if it’s consuming too many resources.

In this post, we will show you how to install and use the Monit monitoring tool on Arch Linux.

Step 1 – Configure Repository

By default, the default repository is outdated in Arch Linux, so you will need to modify the default mirror list. You can do it by editing the mirrorlist configuration file:

nano  /etc/pacman.d/mirrorlist

Remove all lines and add the following lines:

## Score: 0.7, United States
Server = http://mirror.us.leaseweb.net/archlinux/$repo/os/$arch
## Score: 0.8, United States
Server = http://lug.mtu.edu/archlinux/$repo/os/$arch
Server = http://mirror.nl.leaseweb.net/archlinux/$repo/os/$arch
## Score: 0.9, United Kingdom
Server = http://mirror.bytemark.co.uk/archlinux/$repo/os/$arch
## Score: 1.5, United Kingdom
Server = http://mirrors.manchester.m247.com/arch-linux/$repo/os/$arch
Server = http://archlinux.dcc.fc.up.pt/$repo/os/$arch
## Score: 6.6, United States
Server = http://mirror.cs.pitt.edu/archlinux/$repo/os/$arch
## Score: 6.7, United States
Server = http://mirrors.acm.wpi.edu/archlinux/$repo/os/$arch
## Score: 6.8, United States
Server = http://ftp.osuosl.org/pub/archlinux/$repo/os/$arch
## Score: 7.1, India
Server = http://mirror.cse.iitk.ac.in/archlinux/$repo/os/$arch
## Score: 10.1, United States
Server = http://mirrors.xmission.com/archlinux/$repo/os/$arch

Save and close the file, then update all the package indexes with the following command:

pacman -Syu

Step 2 – Install Monit Monitoring Tool

By default, the Monit package is included in the Arch Linux default repository. You can install it easily using the following command.

pacman -S monit

Once Monit is installed, start the Monit service and enable it to start at system reboot.

systemctl start monit
systemctl enable monit

To check the status of Monit, run the following command.

systemctl status monit

You should see the following output.

● monit.service - Pro-active monitoring utility for unix systems
     Loaded: loaded (/usr/lib/systemd/system/monit.service; disabled; preset: disabled)
     Active: active (running) since Wed 2023-01-04 22:14:35 EST; 4s ago
       Docs: man:monit(1)
             https://mmonit.com/wiki/Monit/HowTo
   Main PID: 72648 (monit)
      Tasks: 2 (limit: 2362)
     Memory: 2.2M
     CGroup: /system.slice/monit.service
             └─72648 /usr/bin/monit -I

Jan 04 22:14:35 archlinux systemd[1]: Started Pro-active monitoring utility for unix systems.
Jan 04 22:14:35 archlinux monit[72648]:  New Monit id: c0a3ed9c326d12711c321547eeb05f41
                                         Stored in '/root/.monit.id'
Jan 04 22:14:35 archlinux monit[72648]: Starting Monit 5.32.0 daemon with http interface at [localhost]:2812
Jan 04 22:14:35 archlinux monit[72648]: 'archlinux' Monit 5.32.0 started

Step 3 – Configure Monit

Monit also provides a web interface to monitor your system and services. However, it is disabled by default. You can enable it by editing the Monit default configuration file.

nano /etc/monitrc

Change the following lines to enable the web interface and define the Monit admin username and password.

set httpd port 2812 and
    use address your-server-ip 
#    allow localhost
    allow admin:monit

Save and close the file, then verify the Monit configuration file with the following command.

monit -t

You will get the following output.

Control file syntax OK

Next, restart the Monit service to apply the changes.

systemctl restart monit

At this point, the Monit web interface is enabled and listens on port 2812. You can check it with the following command.

ss -plunt | grep 2812

You should see the following output.

tcp   LISTEN 0      0          127.0.0.1:2812       0.0.0.0:*    users:(("monit",pid=72668,fd=5))                          
tcp   LISTEN 0      0              [::1]:2812             *:*    users:(("monit",pid=72668,fd=6))                          

Step 4 – Monitor Linux System Via Command Line

Monit provides a command line tool to monitor your Linux system via cli.

To check your system information, run the following command.

monit status

You should get the following information.

Monit 5.32.0 uptime: 0m

System 'archlinux'
  status                       OK
  monitoring status            Monitored
  monitoring mode              active
  on reboot                    start
  load average                 [0.01] [0.01] [0.00]
  cpu                          0.0%usr 0.0%sys 0.0%nice 0.0%iowait 0.0%hardirq 0.0%softirq 0.0%steal 0.0%guest 0.0%guestnice 
  memory usage                 270.5 MB [13.6%]
  swap usage                   0 B [0.0%]
  uptime                       18h 38m
  boot time                    Wed, 04 Jan 2023 03:38:23
  filedescriptors              1024 [0.0% of 9223372036854775807 limit]
  data collected               Wed, 04 Jan 2023 22:16:42

Step 5 – Monitor Apache Service with Monit

First, the Apache package must be installed on your server. If not installed, you can install it with the following command.

pacman -S apache

Once the Apache package is installed, start and enable the Apache service with the following command:

systemctl start httpd
systemctl enable httpd

Next, edit the Monit configuration file.

nano /etc/monitrc

Add/modify the following lines to define your Apache server.

#set log syslog
set log /var/log/monit.log

check process apache with pidfile /var/run/httpd/httpd.pid
    start program = "/usr/bin/systemctl start httpd" with timeout 60 seconds
    stop program  = "/usr/bin/systemctl stop httpd"
    if cpu > 60% for 2 cycles then alert
    if cpu > 80% for 5 cycles then restart
    if totalmem > 200.0 MB for 5 cycles then restart
    if children > 250 then restart
    if disk read > 500 kb/s for 10 cycles then alert
    if disk write > 500 kb/s for 10 cycles then alert

Save and close the file, then restart the Monit service to apply the changes.

systemctl restart monit

You can now verify your Apache service status using the following command.

monit summary

You will get the following output.

Monit 5.32.0 uptime: 0m
┌─────────────────────────────────┬────────────────────────────┬───────────────┐
│ Service Name                    │ Status                     │ Type          │
├─────────────────────────────────┼────────────────────────────┼───────────────┤
│ archlinux                       │ OK                         │ System        │
├─────────────────────────────────┼────────────────────────────┼───────────────┤
│ apache                          │ OK                         │ Process       │
└─────────────────────────────────┴────────────────────────────┴───────────────┘

You can also monitor your Apache via web interface using the URL http://your-server-ip:2812. You should see the Monit login page.

Provide your Monit admin username and password and click on the Sign In button. You should see the Monit dashboard on the following screen.

Now, stop the Apache service and check how Monit can start the Apache service automatically.

systemctl stop httpd

You can now check the Monit logs using the following command.

tail -f /var/log/monit.log

You should see that Monit starts the Apache service automatically.

[2023-01-04T22:46:15-0500] info     : Starting Monit 5.32.0 daemon with http interface at [localhost]:2812
[2023-01-04T22:46:15-0500] info     : 'archlinux' Monit 5.32.0 started
[2023-01-04T22:46:45-0500] error    : 'apache' process is not running
[2023-01-04T22:46:45-0500] info     : 'apache' trying to restart
[2023-01-04T22:46:45-0500] info     : 'apache' start: '/usr/bin/systemctl start httpd'

Conclusion

In this post, we showed you how to install Monit on Arch Linux. We also showed you how to monitor Apache service using Monit. You can now add more services to the Monit configuration and monitor them via the Monit dashboard. You can also deploy the Monit monitoring tool on dedicated server hosting from Atlantic.Net!