[Howto] Install and configure Munin on Centos 8

Install munin first:

yum install epel-release -y

yum install munin munin-cgi munin-node munin-apache munin-common munin-plugins-ruby -y

Check the services that munin has installed in systemd:

systemctl list-unit-files | grep -i munin

Enable all available munin plugins:

munin-node-configure --shell --families=contrib,auto | sh -x

Start and enable munin-node which collects data on the system, we restrict this service to localhost:

sed -i /etc/munin/munin-node.conf -e "s,^host \*,#host \*,g"

sed -i /etc/munin/munin-node.conf -e "s,^#host 127.0.0.1,host 127.0.0.1,g"

systemctl enable munin-node --now

Enable munin in systemd timer:

sed -i /etc/munin/munin.conf -e "s,#graph_strategy cron,graph_strategy cron,g"

sed -i /etc/munin/munin.conf -e "s,#html_strategy cron,html_strategy cron,g"

sed -i /etc/munin/munin.conf -e "s,#htmldir,htmldir,g"

systemctl enable munin.timer --now

check if munin timer is running properly

systemctl list-timers --all

and finally add a virtualhost to apache or nginx to show the graphs. Check the examples here (Periodically generate graphs and HTML pages).

For apache: 

<VirtualHost _IP_:80>

    ServerName _IP_

    DocumentRoot /var/www/html

    Alias /munin/static/ /etc/munin/static/

    <Directory /etc/munin/static>

        Require all granted

    </Directory>

    # Disabling caching

    RewriteEngine On

    <FilesMatch "\.(html|htm|jpg|png)$">

      FileETag None

      <IfModule mod_headers.c>

        Header unset ETag

        Header set Cache-Control "max-age=0, no-cache, no-store, must-revalidate"

        Header set Pragma "no-cache"

        Header set Expires "Wed, 12 Jan 1980 05:00:00 GMT"

      </IfModule>

    </FilesMatch>

    # Password protect the folder

    <Directory /var/www/html>

AuthType Basic

AuthName "restricted area"

AuthUserFile /var/www/.htpasswd

require valid-user

    </Directory>

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

    # ScriptAlias /munin /var/www/html/munin/cgi/munin-cgi-html

    <Directory /var/www/html/munin/cgi>

        Require valid-user

        AuthName "restricted area"

            AuthUserFile /var/www/.htpasswd

        <IfModule mod_fcgid.c>

            SetHandler fcgid-script

        </IfModule>

        <IfModule !mod_fcgid.c>

            SetHandler cgi-script

        </IfModule>

    </Directory>

    CustomLog /var/log/httpd/munin-access.log combined

    ErrorLog  /var/log/httpd/munin-error.log

</VirtualHost>

Create your .htpasswd file :

htpasswd -c /var/www/.htpasswd monit

and reload apache.

for nginx add the following to your monit vhost: 

location = / {

    rewrite ^/$ munin/ redirect; break;

}

location /munin/static/ {

    alias /etc/munin/static/;

    expires modified +1w;

}

location /munin/ {

    auth_basic            "Restricted";

    auth_basic_user_file  /var/www/.htpasswd;

    alias /var/www/html/munin/;

    expires modified +310s;

}

location ^~ /munin-cgi/munin-cgi-graph/ {

    auth_basic            "Restricted";

    auth_basic_user_file  /var/www/.htpasswd;

    access_log off;

    fastcgi_split_path_info ^(/munin-cgi/munin-cgi-graph)(.*);

    fastcgi_param PATH_INFO $fastcgi_path_info;

    fastcgi_pass unix:/var/run/munin/munin-cgi-graph.sock;

    include fastcgi_params;

}

then run

service nginx reload

systemctl enable munin-cgi-graph.socket --now