This document is based on using Debian; some information could be different in a different distribution.

Features

Munin is a very flexible and powerful monitoring tool and framework written mainly in Perl for analyzing resources like CPU, memory, hard disks, networks, and services. Munin has two components:

Munin - the server (aka Grapher/Gatherer), which collects all the data and generates graphs.
Munin-Node - the client, which tracks the data from the machine and sends it to the server.
Munin runs on every machine that supports Perl. The database of Munin is based on RRD (Round-Robin-Database).

Requirements

Both
- Operating system which supports and has Perl installed (must be POSIX compatible)
Server
- A configured Webserver/Webapp-Framework, where Munin stores the graphs and web interface.

Installation

Munin is on many Linux distributions installable through a package manager suck as apt, yum, yast, or zypper, This section explains how it works on a Debian 5 (Lenny) machine.

Munin (the server)

Install the server where the Datameer distribution is located using the command:

% sudo apt-get install munin

or on Fedora:

% sudo yum install munin

This installs the server and the client. If you don't want the client on the monitoring machine, then remove munin-node from autostart configuration, such as inittab or rc.d (based on distribution). On some distributions there are no prepackages for Munin, you need to install them manually.

After installation, Munin created the graphs/web interface at the default location, htmldir which can be configured in /etc/munin/munin.conf. The default htmldir is /var/www/munin. If this folder hasn't been created, then wait a while, because the Munin-Server is not a listener which runs as process; it's a script that is executed through Cronjob. You can run the cronjob-run manually as the root user using the following command:
```
% su -c /usr/bin/munin-cron munin
```
If the Script does not return information usin stdout, then everything should be OK.
Now, you can access Munin through any browser.
```
http://SERVERADDRESS/munin
```
You should see "Munin :: Overview" with a list of machines which will be monitored. In this example, you should see the machine you configured as the Munin-Server itself.

Munin-Node (the client)

Install the client where the Datameer distribution is located, using the command:
```
% sudo apt-get install munin-node
```
or on Fedora:
```
% sudo yum install munin-node
```
Next, run a process called munin-node. Munin-Node uses port 4949 by default. If you installed the server and the client on the same machine, you should see graphs in the web interface which are updated every five minutes.

Resources

Locations of the data and configuration, based on the default configuration.

File/Folder	Description
`/etc/cron.d/munin`	Munin-Cronjob (Server)
`/etc/cron.d/munin-node`	Munin-Node-Cronjob (Client)
`/etc/init.d/munin-node`	Control-Script for Munin-Node (Client)
`/etc/logrotate.d/munin`	Logrotator-Script for Munin (Server)
`/etc/logrotate.d/munin-node`	Logrotator-Script for Munin-Node (Client)
`/etc/munin`	Configuration-Folder
`/etc/munin/munin.conf`	Munin-Configuration (Server)
`/etc/munin/munin-node.conf`	Munin-Node-Configuration (Client)
`/etc/munin/plugin-conf.d`	Plugin-Configurations
`/etc/munin/plugins`	The Plugins
`/etc/munin/templates`	Templates for the Web-Interface
`/etc/rc0.d/K20munin-node`	Autorun: Stop Munin-Node (Shutdown)
`/etc/rc1.d/K20munin-node`	Autorun: Stop Munin-Node (Localmode)
`/etc/rc2.d/S98munin-node`	Autorun: Start Munin-Node (Runlevel 2)
`/etc/rc3.d/S98munin-node`	Autorun: Start Munin-Node (Runlevel 3)
`/etc/rc4.d/S98munin-node`	Autorun: Start Munin-Node (Runlevel 4)
`/etc/rc5.d/S98munin-node`	Autorun: Start Munin-Node (Runlevel 5)
`/etc/rc6.d/K20munin-node`	Autorun: Stop Munin-Node (Restart)
`/usr/bin/munin-cron`	The Munin-Cronjob-Script (Server)
`/usr/bin/munindoc`	Shows POD-Documentation for the Plugins of Munin
`/usr/lib/cgi-bin/munin-cgi-graph`	CGI-Script which creates the graphs
`/usr/sbin/munin-node`	Munin-Node-Program (Client)
`/usr/sbin/munin-node-configure`	Munin-Node-Configurator
`/usr/sbin/munin-node-configure-snmp`	Munin-Node-Configurator for SNMP
`/var/lib/munin`	Location where the data are stored (RRD)
`/var/log/munin`	Location where the log files of Munin are stored

Manage Service

Action	Debian	Fedora
Node Start	Execute % /etc/init.d/munin-node start	Execute % /sbin/service munin-node start
Node Status	Execute % /etc/init.d/munin-node status	Execute % /sbin/service munin-node status
Node Stop	Execute % /etc/init.d/munin-node stop	Execute % /sbin/service munin-node stop
Node Restart	Execute % /etc/init.d/munin-node restart	Execute % /sbin/service munin-node restart
Add Node Autostart	Move '$HOME/removed-rcd/rc2.d/S98munin-node', '$HOME/removed-rcd/rc3.d/S98munin-node', '$HOME/removed-rcd/rc4.d/S98munin-node' and '$HOME/removed-rcd/rc5.d/S98munin-node' back to the Runlevel-Directories ('/etc/rc*.d')	Execute % ntsysv Check 'munin-node' and press 'OK'
Remove Node Autostart	Move '/etc/rc2.d/S98munin-node', '/etc/rc3.d/S98munin-node', '/etc/rc4.d/S98munin-node' and '/etc/rc5.d/S98munin-node' to '$HOME/removed-rcd'	Execute % ntsysv Uncheck 'munin-node' and press 'OK'

Configuration

Munin (the server)

By default, you can find the configuration at /etc/munin/munin.conf

Parameter	Default value	Possible values	Description
`dbdir`	/var/lib/munin	Filesystem-Folder	Location of the RRD-Database
`htmldir`	/var/www/munin	Filesystem-Folder	Location where the web interface is stored. (Should be accessible through HTTP)
`logdir`	/var/log/munin	Filesystem-Folder	Location of the log files
`rundir`	/var/run/munin	Filesystem-Folder	Location of Process-State-Files, such as PID
`tmpldir`	/etc/munin/templates	Filesystem-Folder	Location of the templates which are used by the web interface

You can define the structure of monitored machines for the web interface. (The format looks similar to INI-Configuration-sections.)
For example:

[localhost.localdomain]
    address 127.0.0.1
    use_node_name yes

Use a group called localdomain and associate it with the machine localhost and use localhost as the name instead the address in the web interface.
To add a server, copy it and change localhost to the name of the machine and change the IP address to the correct IP address of the machine you want to monitor. For more detailed instructions, see Possible Configuration-Parameters for Munin (Server).

Munin-Node (the client)

By default you can find the configuration at /etc/munin/munin-node.conf. Additional information about this configuration can be found at Possible Configuration-Parameters for Munin-Node (Client).

Parameter	Default value	Possible values	Description
`log_level`	2	0..4	0 = Off, 4 = Maximal Verbose
`log_file`	/var/log/munin/munin-node.log	Logfile-Location	Where the log file should be stored
`pid_file`	/var/run/munin/munin-node.pid	Pidfile-Location	Where the PID file should be stored
`background`	1	1 or comment out and set setsid to 0	Set to 1 to run in the background, or set to 0.
`user`	root	User	Run node below this user
`group`	root	Group	Run node below this group
`setsid`	yes	yes/1 or no/0	Fork after bind to daemonize or not
`ignore_file`	~$	Expression for excluding Files	Regular expression to exclude files which match this expression (This command can be repeated)
`allow`	^127\.0\.0\.1$	Expression for IP-Address	Regular expression of IP to allow access on node (This command can be repeated)
`host`	*	IP-Address or * for all	The address where the node will listen
`port`	4949	1..65534	The port where the node will listen
`cidr_allow`	-	CIDR for IP-Address	Allows use of CIDR- notation See http://en.wikipedia.org/wiki/CIDR_notation
`cidr_deny`	-	CIDR for IP-Address	Cancels (or negates) cidr_allow See http://en.wikipedia.org/wiki/CIDR_notation

If the cidr_* parameter won't work in the configuration, use allow instead; which command is supported depends on the version of Perl Net::Server.

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