How to install and configure Munin on Centos

Munin the power full monitoring tool monitor all of your servers or computers and remembers what it saw.

It presents all the information in graphs through a web interface and also available on Android.

Munin has plug and play capabilities. After completing a installation a high number of monitoring plugins will be playing with no more effort.

Using Munin, you can easily monitor the performance of your servers, computers, networks, SANs, applications, weather measurements and whatever comes to mind.

It will makes it you easily to determine “what’s different today” when a performance problem found.

Munin uses the excellent ​RRDTool written by Tobi Oetiker) and the framework is written in Perl, while plugins may be written in any language.

Also Read: How to install Netdata to monitor your linux system

Munin also has a master/node architecture in which the master connects to all the nodes at regular intervals and asks them for data.

You can read more about Munin on http://munin-monitoring.org

How to install Munin on Centos 7

Enable Epel repository

# yum -y install epel-release

Update system with command

# yum update

Install Munin and Apache

# yum install munin munin-node httpd -y

Start and enable munin-node

# systemctl enable munin-node
# systemctl start munin-node

Create configuration on /etc/httpd/conf.d/httpd.conf

Alias /munin /var/www/html/munin

Options FollowSymLinks
AllowOverride All
Order allow,deny
Allow from all
AuthUserFile /etc/munin/munin-htpasswd
AuthName "serverdiary"
AuthType Basic
require valid-user
ExpiresActive On
ExpiresDefault M310

ScriptAlias /munin-cgi/munin-cgi-graph /var/www/cgi-bin/munin-cgi-graph

  AuthUserFile /etc/munin/munin-htpasswd
  AuthName "serverdiary"
  AuthType Basic
  require valid-user

Create authentication file on /etc/munin/munin-htpasswd

# htpasswd -c /etc/munin/munin-htpasswd serverdiary

Change owner of /var/www/html/munin to munin

# chown -R munin.munin /var/www/html/munin

Configure Munin to monitor Apache

Create apache server status configuration on /etc/httpd/conf.d/server-status.conf

ExtendedStatus on

   SetHandler server-status
   Deny from all
   Allow from 127.0.0.1
   Allow from localhost

Create munin configuration on /etc/munin/plugin-conf.d/apache_

[apache_processes]
env.url http://localhost:%d/server-status?auto
env.ports 80

[apache_accesses]
env.url http://localhost:%d/server-status?auto
env.ports 80

[apache_volume]
env.url http://localhost:%d/server-status?auto
env.ports 80

[apache_memmory]
env.apuser apache
env.binname httpd

[apache_threads]
env.apuser apache
env.binname httpd

Add Apache plugins to /etc/munin/plugins directory using symbolic link

# ln -s /usr/share/munin/plugins/apache* /etc/munin/plugins/

Restart apache and munin-node

# systemctl restart httpd

Configure Munin to monitor Nginx

Create Nginx server status configuration on /etc/nginx/conf.d/server-status.conf

server {
  listen 80;
  server_name localhost 127.0.0.1;

  access_log off;
  allow 127.0.0.1;
  deny all;

  location /nginx_status {
    stub_status;
	stub_status on;
  }
  location /stub_status {
    stub_status;
	stub_status on;
  }
  location / {
    root   /usr/share/nginx/html;
	index index.html index.htm;
  }
}

Create Munin plugin configuration on /etc/munin/plugin-conf.d/nginx_

[nginx*]
env.url http://localhost/nginx_status

[nginx_error]
env.logpath    /var/log/nginx
env.logpattern *.error.log

Add Nginx plugins to /etc/munin/plugins directory using symbolic link

# ln -s /usr/share/munin/plugins/nginx* /etc/munin/plugins/

If you use Nginx as reverse proxy, add this configuration to Nginx server

server {
	listen   *:443 ssl http2;
	.....
	.....
	location ~ ^/(munin|munin-cgi/munin-cgi-graph) {
		proxy_set_header        Host $host;
		proxy_set_header        X-Real-IP $remote_addr;
		proxy_set_header        X-Forwarded-For $proxy_add_x_forwarded_for;
		proxy_set_header        X-Forwarded-Proto $scheme;

		proxy_pass          http://localhost;
		proxy_connect_timeout 90;
		proxy_send_timeout 90;
		proxy_read_timeout 90;

		client_max_body_size 10m;
		client_body_buffer_size 128k;		

		proxy_buffer_size 64k;
		proxy_buffers 8 64k;
		proxy_busy_buffers_size 256k;
		proxy_temp_file_write_size 256k;
	}
	.....
	.....
}

Restart munin-node and wait for a while

# systemctl restart munin-node

Now you can check http://your_ip_or_your_domain/munin

Configure Munin to monitor MySQL / MariaDB

Check if perl-Cache-Cache already installed

# yum install perl-Cache-Cache

Create MySQL user for Munin with mysql command below

mysql> CREATE USER 'munin'@'localhost' IDENTIFIED BY 'password';
mysql> GRANT PROCESS, SUPER ON . TO 'munin'@'localhost';
mysql> GRANT SELECT ON mysql.* TO 'munin'@'localhost';
mysql> CREATE DATABASE IF NOT EXISTS muninmonitor;
mysql> GRANT ALL PRIVILEGES ON munin.* TO 'muninmonitor'@'localhost';
mysql> FLUSH PRIVILEGES;

Create configuration file on /etc/munin/plugin-conf.d/mysql_

[mysql_*]
env.mysqlconnection DBI:mysql:mysql;host=127.0.0.1;port=3306
env.mysqluser munin
env.mysqlpassword password
[mysql*]
env.mysqladmin /usr/bin/mysqladmin
env.mysqluser munin
env.mysqlpassword password

Create configuration file on /etc/munin/plugin-conf.d/mysql_innodb_

[mysql_*] 
env.mysqlconnection DBI:mysql:mysql;host=127.0.0.1;port=3306
env.mysqluser munin
env.mysqlpassword password
env.cachenamespace munin_mysql_pri

[mysql_innodb]
env.warning 0
env.critical 0

Create shell script to make plugins symbolic link, example on /root/munin_symlink.sh

#!/bin/sh
set -eu
for i in bin_relay_log commands connections files_tables innodb_bpool innodb_bpool_act innodb_insert_buf innodb_io innodb_io_pend innodb_log innodb_rows innodb_semaphores innodb_tnx myisam_indexes network_traffic qcache qcache_mem replication select_types slow sorts table_locks tmp_tables; do
    echo "--- $i ---"
    rm -f /etc/munin/plugins/mysql_$i
    ln -s /usr/share/munin/plugins/mysql_ /etc/munin/plugins/mysql_$i
done

Change permission to 755 and then execute shell script.

# chmod 755 /root/munin_symlink.sh
# /root/munin_symlink.sh

Restart munin and force run munin cron

# systemctl restart munin-node
# sudo -u munin munin-cron

How to Force Munin update html and graphics generation

To regenerate html and graphs in /var/www/html/munin run:

root@serverdiary:~# sudo -u munin munin-cron