Install Monit on Linux

Monit is a free and open-source tool that enables Unix users to manage and monitor their systems. With automatic maintenance and repair, this small utility executes helpful actions when something goes wrong. In this article, you will learn How to Install Monit on Linux to Monitor a Server.

When you buy Linux VPS, you must be able to use Monit since most Unix distributions include it. But if not, follow the steps of this tutorial to learn how to install and configure Monit on your Linux.

What is Monit & Why should we Use it?

As a system administrator, you will find Monit a very helpful tool since it monitors and manages processes, files, directories, checksums, permissions, and filesystems automatically. Also, on Unix/Linux-based systems and providers, it manages and monitors services like Apache, Nginx, MySQL, FTP, SSH, and SMTP. Monit includes a simple HTTP(S) interface that you may use to browse the Monit server and view the status of all services that are being tracked. You can start, stop, and restart processes as well as disable or enable service monitoring through the web interface.

A process can be started by Monit if it is not already running, restarted if it is not responding, and stopped if it consumes too many resources. Additionally, Monit may be used to keep an eye on timestamps, checksum, file size, and other changes in files, directories, and filesystems. You can use Monit to track the TCP/IP port, server protocols, and ping of distant hosts. Monit maintains its own log file and notifies users of any urgent error circumstances and recovery progress.

Previously, you have learned about the Load Average in Linux. Install Monit on Linux allows you to keep an eye on localhost’s system resources in general, including average load, memory consumption, and CPU usage.

Tutorial Install and Setup Monit on Linux

This content presents the Monit installation and configuration on RHEL-based and Debian-based Linux distributions, So, CentOS, RHEL, Fedora, Ubuntu, and Debian users can use the following instructions. Let’s go through the steps of this guide to learn how to install Monit on Linux.

Step1. Install Monit on Linux

Since the Monit utility is not available from the default system base repositories, you need to install epel repository first.

On RHEL 8 & 9 based systems:

# dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

# dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-9.noarch.rpm 

On RHEL 7-based Systems:

# yum install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm

On Fedora 22+:

# dnf install monit

On Debian and Ubuntu:

$ sudo apt-get install monit

On Arch Linux:

$ pacman -S monit

Run the following commands to install the Monit packages when you are finished adding the epel repository.

# yum install monit

On Fedora Linux:

# dnf install monit

Step 2. Setup Monit on Linux

Install Monit on Linux was successfully completed in the previous step. Now, you are ready to configure it. This step is very easy. You just need to make changes in the Monit configuration file since it has a web interface that runs on port 2812 using a web server.

The main configuration file of monit is located at /etc/monit.conf under (RedHat/CentOS/Fedora) and /etc/monit/monitrc file for (Ubuntu/Debian/Linux Mint).

Open your preferred editor and edit the file below:

# vi /etc/monitrc

OR

$ sudo nano /etc/monit/monitrc

Uncomment the next section, add your server’s IP address or domain name, enable public connections, and either modify the monit user and password or go with the defaults.

set httpd port 2812 and
     use address 0.0.0.0  # only accept connections from localhost
     allow 0.0.0.0/0        # allow localhost to connect to the server and
     allow admin:monit      # require user 'admin' with password 'monit'
     allow @monit           # allow users of group 'monit' to connect (rw)
     allow @users readonly  # allow users of group 'users' to connect readonly

Once configured, the Monit service must be started, enabled, and verified in order to reload the modified configuration settings.

# systemctl start monit
# systemctl enable monit
# systemctl status monit

Step 3. Access the Monit Web Interface

the two previous steps helped you to Install Monit on Linux. Now, you are ready to access the Monit web interface. Just navigate to the following URLs:

http://localhost:2812

OR

http://ip-address:2812

OR

http://example.com:2812

Then type “admin” for the user’s name and “monit” for the password. You ought to see a screen like the one below.

Now navigate to 2812 on localhost in your browser to open the Monit web interface.

The Monit web interface is set up now.

Step 4. Add Linux Services in Monit

As we mentioned, Apache, Nginx, MySQL, FTP, SSH, and SMTP are the services that Monit can monitor them. In this step, you are ready to add these Linux services to Monit Mentoring. Let’s see some useful examples. To do this, you need to edit your monit configuration file and add the following settings at the end of the file.

How to Monitor Apache in Monit

check process httpd with pidfile /var/run/httpd.pid
group apache
start program = "/usr/bin/systemctl httpd start"
stop program = "/usr/bin/systemctl httpd stop"
if failed host 127.0.0.1 port 80
protocol http then restart
if 5 restarts within 5 cycles then timeout

How to Monitor Apache2 in Monit

check process apache with pidfile /run/apache2.pid
start program = "/usr/bin/systemctl apache2 start" with timeout 60 seconds
stop program  = "/usr/bin/systemctl apache2 stop"

Apache can be stopped or restarted by Monit, which can also notify you. Process attributes, such as how much memory or CPU time a process is using, can also be tracked by Monit.

How to Monitor Nginx in Monit

check process nginx with pidfile /var/run/nginx.pid
start program = "/usr/bin/systemctl nginx start"
stop program = "/usr/bin/systemctl nginx stop"

How to Monitor MySQL in Monit

check process mysqld with pidfile /var/run/mysqld/mysqld.pid
group mysql
start program = "/usr/bin/systemctl mysqld start"
stop program = "/usr/bin/systemctl mysqld stop"
if failed host 127.0.0.1 port 3306 then restart
if 5 restarts within 5 cycles then timeout

How to Monitor SSH in Monit

check process sshd with pidfile /var/run/sshd.pid
start program "/usr/bin/systemctl sshd start"
stop program "/usr/bin/systemctl sshd stop"
if failed host 127.0.0.1 port 22 protocol ssh then restart
if 5 restarts within 5 cycles then timeout

 How to Monitor MySQL/MariaDB in Monit

check process mysqld with pidfile /var/run/mysqld/mysqld.pid
    start program = "/etc/init.d/mysql start"
    stop program = "/etc/init.d/mysql stop"

Depending on the version of MySQL you have installed, the PID file’s location and init script may change.

Step 5. Verify Monit Syntax for Errors

Once you’ve set up every program for monitoring, look for any mistakes in the monit syntax.

# monit -t

OR

$ sudo monit -t

Then, use the commands below to start the Monit service:

# systemctl monit restart

OR

$ sudo systemctl monit restart

Monit can act if an error situation should occur. At this point, you have verified the configuration, and you are ready to use the Monit monitoring program on Linux.

FAQ

Conclusion

In this article, you learned How to Install Monit on Linux to Monitor a Server. This content helps you to benefit from all features needed for system monitoring and error recovery. It’s like having a watchdog with a toolbox on your server. The above steps help you to start using Monit and benefit from all features needed for system monitoring and error recovery.

If you follow the above steps properly then you can smoothly install and configure Monit without any errors but do not hesitate to contact us if you encounter any problems. Our technical support team will try their best to solve your problems.