Munin is an excellent system monitoring tool similar to RRD tool which will give you ample information about system performance on multiple fronts like a disk, network, process, system, and users. These are some of the default properties Munin monitors.
How Munin works?
Munin works on a client-server model. Munin server process on the main server try to collect data from client daemon which is running locally(Munin can monitor it’ss own resources) or from a remote client(Munin can monitor hundreds of machines) and displays them in graphs on it’s web interface.
Configuring Munin in nutshell
This is of two steps as we have to configure both server and client.
1)Install Munin server package and configure it so that it get data from clients.
2)Configure Munin client so that server will connect to client daemon for data collocation.
Install munin server in Linux
Munin server installation on Ubuntu/Debian based machines
apt-get install munin apache2
Munin server installation on Redhat/Centos based machines. Make sure that you enable EPEL repo before installing Munin on Redhat based machines as by default Redhat based machines do not have Munin in their repos.
yum install munin httpd
Configuring Munin server in Linux
Below are the steps we have to do in order to bring the server up.
1) Add host details which need monitoring in /etc/munin/munin.conf
2) Configure apache web server to include munin details.
3) Create Username and password for web interface
4) Restart apache server
Step 1: Add hosts entry in this file in /etc/munin/munin.conf. Go to the end of the file and a client to monitor. Here in this example, I added my DB server and it’s IP address to monitor
[db.linuxnix.com] address 192.168.1.25 use_node_name yes
Save the file and exit.
Step 2: Edit/create munin.conf file in /etc/apache2/conf.d folder to include Munin Apache related configs. In another note, by default other Munin web related configs are kept in /var/www/munin folder.
Alias /munin /var/www/munin <Directory /var/www/munin> Order allow,deny Allow from localhost 127.0.0.0/8 ::1 AllowOverride None Options ExecCGI FollowSymlinks AddHandler cgi-script .cgi DirectoryIndex index.cgi AuthUserFile /etc/munin/munin.passwd AuthType basic AuthName "Munin stats" require valid-user <IfModule mod_expires.c> ExpiresActive On ExpiresDefault M310 </IfModule> </Directory>
Save the file and exit
Step 3: Now create a username and password for viewing Munin graphs:
htpasswd -c /etc/munin/munin-htpasswd munin
Note: For Redhat/Centos machines replace “apache2” with “httpd” in each path to access your config files.
Step 3: Restart Apache server so that Munin configurations are picked-up by Apache.
service apache2 restart
service httpd restart
Install and configure Munin client in Linux
Step 1: Install Munin client in Linux
apt-get install munin-node
Note: If you want to monitor your Munin server, then you have to install Munin-node on that as well.
Step 2: Configure client by editing Munin-node.conf file.
allow ^127\.0\.0\.1$ allow ^10\.10\.20\.20$
# Which address to bind to; host *
# And which port port 4949
Note: 10.10.20.20 is my Munin server and it’s connections to 4949 port on client to get it’s data.
Step 3: Restart Munin-node on client server
service munin-node restart
Check if you are able to connect client from the server on 4949 port, otherwise, you have to open that port on the client machine.
telnet db.linuxnix.com 4949
Just a side note: We can send munin understandable commands like list, nodes, config, fetch etc. If you want to fetch CPU details execute below command once you connected to 4949 port.
fetch cpu user.value 40755020 nice.value 125960 system.value 43575690 idle.value 46709201946 iowait.value 1081255 irq.value 3264 softirq.value 107719 steal.value 408952
Accessing Munin web interface
Hope this helps to configure basic Munin server.
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