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Munin

Munin is a plain monitoring program with no notification possibility. It uses rrd to store and create graphs for servers. It can use SNMP to monitor windows servers.

http://munin.projects.linpro.no/

How Munin works

Munin has a sort of client / server solution, although the server is just a script that collects the data in certain time periods.

The client is a node to which the server scripts connect and collect data.

Setup Client (Node)

remark for non debian systems, it might be different

install the munin-node package and open the /etc/munin/munin-node.conf file.

The only things you need to change here is the host_name and the allow part. The host_name is the server name (FQDN). allow is a regex formated IP which are allowed to access the node.

 allow ^127\.0\.0\.1$
 allow ^192\.168\.\d{1,3}\.\d{1,3}$

after changes the munin-node has to be restartet. To see if the node works, connect to it:

 telnet <node ip> 4949

you will be greeted with a simple screen:

 Trying 127.0.0.1...
 Connected to localhost.
 Escape character is '^]'.
 # munin node at linux-debian-clemens.tokyo.tequila.jp

you can use the following commands list, nodes, config, fetch, version, quit

Setup Server

Setting up the server is not more difficult. For Linux/Unix nodes it is nothing more than adding a small config entry into the /etc/munin/munin.conf file.

Basic settings are there the db (rrd files), html, log etc is. At least see that the htmldir is correctly set.

Because the graphs are by default a bit too small - line breaks in the legend make them too high - increase the width to 500

graph_width 500

a normal linux/unix node is added like this

 [host.domain.net]
     address 192.168.20.15
     use_node_name yes

for adding a windows node please see the excellent guide on the munin homepage: http://munin.projects.linpro.no/wiki/HowToMonitorWindows

one very important remark A windows entry in the server config file has NOT the ip address from the target server but from the munin server instead. Second the use_node_name has to be turned off

 [uni.tokyo.tequila.jp]
     address 127.0.0.1
     use_node_name no

MORE CONFIG SETTINGS FOR GROUPINGS NEEDED

Show Graphs

point your browser to the server where munin runs. In the default the munin directory is in the document root of the default host, eg http://foo.com/munin/

Munin and GRS and other secure kernels

Munin runs all its queries as the munin user. Might be good, but it suck because on super secure servers some fail. Eg on a 2.4grs kernel the netstat cannot be run by a normal user, because it cannot access the /proc/net/snmp file. So also munin read fails.

I did not find out a way around this. Of course you can hack the munin-node.pl file, but I don't think thats the ideal solution

SOLUTION NEEDED FOR THIS

working around this with sudo does not work either. Although the output looks correct when directly called, it does not work if it is called through node itself.