# MuninLite MuninLite is a standalone shell script implementing the Munin protocol and containing a few basic plugins out of the box. It can run as an inetd-based service over TCP or a simple executable script communicating via stdin/stdout. The latter does not require root privileges. # Project scope Muninlite is supposed to be a minimal portable and shell-based implementation of `munin-node`. It provides a small set of essential plugins suitable for basic monitoring of a host. Additionally external plugins can be used. Only essential tools (e.g. the ones provided by busybox) should be required for MuninLite. # Missing features (by design) The following features of the official `munin-node` implementation are not included (see "Project scope" above): * no configuration per plugin (e.g. environment variables or reduced privileges) * no host-based access control for incoming requests (may be configured via `/etc/hosts.allow` or firewall rules) * no advanced plugin state tracking (e.g. killing a plugin process after a timeout) # Installation ## Build requirements * Make * Perl ## Installation Download source and unpack it. Assemble the MuninLite shell script by running `make`: ```shell $ make ``` You may assemble a reduced script by including only specific plugins: ```shell $ make PLUGINS="cpu load uptime" ``` Run `make install` or simply copy `muninlite` to a suitable location. ```shell make install ``` 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/muninlite ``` 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/local/bin/muninlite`): ```shell $ /usr/local/bin/muninlite # 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 example.org 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 example.org version: 0.0.5 (munin-lite) quit Connection closed by foreign host. ``` # Configuration ## Plugin configuration To configure which plugins should be enabled, locate the `PLUGINS` variable in `muninlite` and remove unwanted plugins. There is no specific configuration for plugins. ## External plugins MuninLite includes a set of integrated plugins. In addition it is possible to expose additional plugins (just like the official `munin-node` implementation). By default all executables files (or symlinks) below the directory `/etc/munin/plugins` are treated as plugins. ## Munin master configuration Configure your /etc/munin/munin.conf as you would for a regular `muninnode`, 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/muninlite use_node_name yes ``` # License and copyright MuninLite is released under GPLv2 (see LICENSE file). * Copyright (C) 2007-2011 Rune Nordbøe Skillingstad * Copyright (C) 2019-2020 Lars Kruse