README for MuninLite

MuninLite is a single Bourne Shell script that implements the Munin protocoll as well as some Linux specific plugins. The motivation for developing MuninLite was to provide a simple Munin Node, using inetd on systems without a full featured Perl and/or bash or a busybox system.

Features

MuninLite implements the following plugins:

df
cpu
if_
if_err_
load
memory
processes
swap
netstat
uptime
interrupts
irqstats

Included files

Changelog: Changelog
CREDITS: Credits to contributors
LICENSE: GPLv2 License
Makefile: Rules to make munin-node
README: This file
TODO: Things to do in future releases
VERSION: Current version
munin-node.in: The MuninLite script skeleton
examples/xinetd.d/munin: Sample xinetd configuration
examples/inetd.conf: Sample inetd.conf configuration
examples/inetd.busybox: Sample inetd.conf configuration for busybox
examples/hosts.deny: Sample hosts.deny configuration
examples/hosts.allow: Sample hosts.allow configuration
plugins/cpu: CPU usage plugin
plugins/df: Filesystem usage plugin
plugins/if_: Network interface traffic plugin
plugins/if_err_: Network interface errors plugin
plugins/interrupts: Interrupts & context switches plugin
plugins/irqstats: Individual interrupts plugin
plugins/load: Load average plugin
plugins/memory: Memory usage plugin
plugins/netstat: Netstat plugin
plugins/processes: Number of Processes plugin
plugins/swap: Swap in/out plugin
plugins/uptime: Uptime plugin

Build requirements

Make: not sure what requirements
Perl: even very old versions should work

Requirements

Bourne Shell: ash or dash should be sufficient
grep: simple grep in busybox is sufficient
sed: simple sed in busybox is sufficient -- but a bit strange...
cut: cut in busybox is sufficient
wc: wc in busybox is sufficient
xargs: xargs in busybox is sufficient
inetd: inetd in busybox is sufficient

Installation

Download source and unpack it. Edit Makefile to suit your choice of plugins

Make munin-node by running "make"

$ make
Making munin-node for muninlite version 0.9.14
Adding plugin df
Adding plugin cpu
Adding plugin if_
Adding plugin if_err_
Adding plugin load
Adding plugin memory
Adding plugin processes
Adding plugin swap
Adding plugin netstat
Adding plugin uptime
Adding plugin interrupts
Adding plugin irqstats

Copy munin-node to a suitable location (/usr/local/bin/) and make it executable (there will be a "make install" at a later release)

cp munin-node /usr/local/bin
chmod +x /usr/local/bin/munin-node

Add munin port to /etc/services:

echo "munin           4949/tcp        lrrd            # Munin" >>/etc/services

Configure inetd or xinetd to fork this script for request on the munin port (4949).

Sample configuration for xinetd is located in examples/xinetd.d/munin:

cp examples/xinetd.d/munin /etc/xinetd.d
killall -HUP xinetd

Sample configuration for inetd is located in examples/inetd.conf:

cat examples/inetd.conf >> /etc/inetd.conf
killall -HUP inetd

Restrict access to munin port using hosts.allow and hosts.deny or add a rule to your favorite firewall config. Examples of hosts.allow/deny settings is provided in the examples directory.

Iptables might be set with something like this:

iptables -A INPUT -p tcp --dport munin --source 10.42.42.25 -j ACCEPT

Test

To test script, just run it (/usr/bin/local/munin-node):

$ /usr/local/bin/munin-node
# munin node at localhost.localdomain
help
# Unknown command. Try list, nodes, config, fetch, version or quit
list
df cpu if_eth0 if_eth1 if_err_eth0 if_err_eth1 load memory
version
munins node on mose.medisin.ntnu.no version: 0.0.5 (munin-lite)
quit

For inetd-test, try to telnet to munin port from allowed host.

# telnet localhost 4949
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
# munin node at localhost.localdomain
help
# Unknown command. Try list, nodes, config, fetch, version or quit
list
df cpu if_eth0 if_eth1 if_err_eth0 if_err_eth1 load memory
version
munins node on mose.medisin.ntnu.no version: 0.0.5 (munin-lite)
quit
Connection closed by foreign host.

Plugin configuration

To configure which plugins should be enabled, locate the PLUGINS variable in munin-node and remove unwanted plugins.

There is no specific configuration for plugins.

Munin configuration

Configure your /etc/munin/munin.conf as you would for a regular munin-node.

[some.host.tld]
    address 10.42.42.25
    use_node_name yes

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