muninlite/README.md

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 Nordb<64>e 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

Build requirements
------------------
* Make
* Perl

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 (optional): inetd in busybox is sufficient

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

Assemble the munin-node shell script by running `make`:
```shell
$ make
```

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
```

Two typical ways of using MuninLite as a `munin-node` replacement are:

* direct execution: suitable for remote hosts lacking root access (e.g. shared host)
* TCP service via inetd/xinetd: providing a service that is accessible via TCP (like `munin-node`)

Both approaches are detailed below.


Installation for direct execution
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Configure the `address` setting of the node in the master's configuration with
a suitable transport, e.g.:
```
[some.host.tld]
    address ssh://node-a.example.org/usr/local/bin/munin-node
```

The above example causes the master to connect to the node via ssh and to
execute the MuninLite script directly.  The running script responds to request
from standard input just like it would do as a TCP service via inetd/xinetd.


Installation as a TCP service (inetd/xinetd)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Add munin port to `/etc/services` (in case it is missing):
```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 the 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`, if you configured MuninLite as a TCP service (e.g. via
inetd/xinetd):

```
[some.host.tld]
    address 10.42.42.25
    use_node_name yes
```

In case of direct execution of MuninLite on the remote host (without a TCP
service), you need to configure a transport and execute the script directly:
```
[some.host.tld]
    address ssh://10.42.42.25/usr/local/bin/munin-node
    use_node_name yes
```