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.

MuninLite is Copyright (C) 2007 Rune Nordbøe Skillingstad
<rune@skillingstad.no> and released under GPLv2 (see LICENSE file)

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"
```shell
$ 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)

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

Add munin port to `/etc/services`:
```shell
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`:
```shell
cp examples/xinetd.d/munin /etc/xinetd.d
killall -HUP xinetd
```

Sample configuration for inetd is located in `examples/inetd.conf`:
```shell
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:
```shell
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`):
```shell
$ /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.
```shell
# 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
```