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howto:munin_monitoring 2010/12/13 22:47 howto:munin_monitoring 2017/09/06 18:38 current
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====== How to set up Munin monitoring ====== ====== How to set up Munin monitoring ======
 +
 +[[http://munin-monitoring.org/|Munin]] is a lightweight and simple monitoring system. It can gather statistics from different networked machines, including NAS devices like DNS-323. Munin consists of a //master// that collects, stores and visualizes data from a number of //nodes//, and this tutorial describes how to configure DNS-323 to act as a Munin node.
 +
 +{{howto:munin-example.png}}
 +
 +===== Munin node =====
 +
 +This article assumes that [[howto:ffp|ffp]] is already installed on the device.
 +
 +You should login to the device either over ssh or telnet, cd to a directory on a filesystem with enough free space and download the funpkg packages (currently hosted on the forum)
 +
 +  # chdir /mnt/HD_a2
 +  # wget http://www.inreto.de/dns323/fun-plug/0.5/extra-packages/perl/perl-5.10-2.tgz
 +  # wget -O munin-node-1.4.5-2.tgz http://dns323.kood.org/forum/attachment.php?item=662
 +  # wget -O perl-mod-Net-Server-0.99-1.tgz http://dns323.kood.org/forum/attachment.php?item=661
 +
 +When the download is complete the packages should be installed
 +
 +  # funpkg -i perl-5.10-2.tgz
 +  Installing package perl-5.10-2 ...
 +  # funpkg -i perl-mod-Net-Server-0.99-1.tgz
 +  Installing package perl-mod-Net-Server-0.99-1 ...
 +  # funpkg -i munin-node-1.4.5-2.tgz
 +  Installing package munin-node-1.4.5-2 ...
 +  [...]
 +  Executing install script for munin-node-1.4.5-2 ...
 +
 +Munin has a modular architecture, and information about individual components of a system is provided by plugins. None are enabled by default, but there is an auto-detection mechanism available that can guess which plugins might be useful on a given machine. You can either enable plugins manually by symlinking scripts from ''/ffp/lib/plugins/cpu'' to ''/ffp/etc/munin/plugins/'' or rely on Munin to do this automatically using
 +
 +  # perl /ffp/sbin/munin-node-configure --shell | sh -x
 +  # The following plugins caused errors:
 +  [...]
 +  + ln -s /ffp/share/munin/plugins/cpu /ffp/etc/munin/plugins/cpu
 +  + ln -s /ffp/share/munin/plugins/diskstats /ffp/etc/munin/plugins/diskstats
 +  + ln -s /ffp/share/munin/plugins/entropy /ffp/etc/munin/plugins/entropy
 +  + ln -s /ffp/share/munin/plugins/forks /ffp/etc/munin/plugins/forks
 +  + ln -s /ffp/share/munin/plugins/fw_packets /ffp/etc/munin/plugins/fw_packets
 +  + ln -s /ffp/share/munin/plugins/http_loadtime /ffp/etc/munin/plugins/http_loadtime
 +  + ln -s /ffp/share/munin/plugins/interrupts /ffp/etc/munin/plugins/interrupts
 +  + ln -s /ffp/share/munin/plugins/iostat /ffp/etc/munin/plugins/iostat
 +  + ln -s /ffp/share/munin/plugins/iostat_ios /ffp/etc/munin/plugins/iostat_ios
 +  + ln -s /ffp/share/munin/plugins/irqstats /ffp/etc/munin/plugins/irqstats
 +  + ln -s /ffp/share/munin/plugins/load /ffp/etc/munin/plugins/load
 +  + ln -s /ffp/share/munin/plugins/memory /ffp/etc/munin/plugins/memory
 +  + ln -s /ffp/share/munin/plugins/nfs4_client /ffp/etc/munin/plugins/nfs4_client
 +  + ln -s /ffp/share/munin/plugins/nfsd /ffp/etc/munin/plugins/nfsd
 +  + ln -s /ffp/share/munin/plugins/nfsd4 /ffp/etc/munin/plugins/nfsd4
 +  + ln -s /ffp/share/munin/plugins/open_files /ffp/etc/munin/plugins/open_files
 +  + ln -s /ffp/share/munin/plugins/open_inodes /ffp/etc/munin/plugins/open_inodes
 +  + ln -s /ffp/share/munin/plugins/proc_pri /ffp/etc/munin/plugins/proc_pri
 +  + ln -s /ffp/share/munin/plugins/processes /ffp/etc/munin/plugins/processes
 +  + ln -s /ffp/share/munin/plugins/swap /ffp/etc/munin/plugins/swap
 +  + ln -s /ffp/share/munin/plugins/threads /ffp/etc/munin/plugins/threads
 +  + ln -s /ffp/share/munin/plugins/uptime /ffp/etc/munin/plugins/uptime
 +  + ln -s /ffp/share/munin/plugins/users /ffp/etc/munin/plugins/users
 +
 +Munin plugins are in fact simple scripts with plain-text output that can be executed using ''munin-run''
 +
 +  # perl -T /ffp/sbin/munin-run cpu     
 +  user.value 6639837
 +  nice.value 0
 +  system.value 6932479
 +  idle.value 186026521
 +  iowait.value 2634360
 +  irq.value 8
 +  softirq.value 209867
 +  steal.value 0
 +
 +
 +The 'df' script (/ffp/share/munin/plugins/df) not work properly because the busybox df command is less about.
 +Change the original line to the repaired line:
 +
 +The original line: 
 +  my $dfopts = "-P -l".join(' -x ',('',split('\s+',$exclude)));
 +The repaired line
 +  my $dfopts = "-k | grep -v -e /dev/loop0 -e rootfs";
 +
 +or use this script:
 +  #!/ffp/bin/sh
 + 
 +  cp /ffp/share/munin/plugins/df /ffp/share/munin/plugins/df_bak
 +  cat /ffp/share/munin/plugins/df_bak | sed 's/my \$dfopts = "-P -l".*$/my $dfopts = "-k | grep -v -e \/dev\/loop0 -e rootfs";/' > /ffp/share/munin/plugins/df
 +  ln -s /ffp/share/munin/plugins/df /ffp/etc/munin/plugins
 +  killall -9 munin-node
 +  /ffp/start/munin-node.sh restart
 +
 +Be aware that some plugins may require additional dependencies.
 +
 +A newly installed Munin node accepts only localhost connections, so you should modify ''/ffp/etc/munin/munin-node.conf'' to allow at least incoming connections from the Munin master
 +
 +  allow ^127\.0\.0\.1$
 +  allow ^191\.168\.1\.2$
 +
 +Of course you should substitute ''191.168.1.2'' with the IP of the Munin master. The addresses look weird because the ''allow'' directives takes Perl regular expressions, and dots have to be escaped.
 +
 +The next step is to enable the ''munin-node'' daemon
 +
 +  # chmod a+x /ffp/start/munin-node.sh
 +  # /ffp/start/munin-node.sh start
 +
 +In order to verify that the node is up and running you can connect to it and invoke a command which lists all available plugins
 +
 +  # nc localhost 4949
 +  # munin node at localhost
 +  list << YOU SHOULD TYPE THIS AND PRESS ENTER
 +  cpu entropy forks fw_packets http_loadtime interrupts ...
 +
 +You can try the same command from the Munin master to make sure that it can connect to the node.
 +
 +For additional security ''munin-node'' can be run from inetd or tunnelled over SSH, but this is beyond the scope of this tutorial.
 +
 +===== Munin master ====
 +
 +When the node is up and running all that you need is a master that will collect, store and visualize the data.
 +
 +The Munin master should be installed on a server that is always on and has network access to all the nodes. Most decent Linux distributions should have a Munin package available, and if not you should follow [[http://munin-monitoring.org/wiki/Documentation|the documentation]].
 +
 +In case of Debian-based distributions the installation is as simple as
 +
 +  $ sudo apt-get install munin
 +
 +Then you should edit the ''/etc/munin/munin.conf'' configuration file and add a following entry
 +
 +  [dns323]
 +      address 192.168.1.3
 +      use_node_name yes
 +
 +Instead of ''dns323'' you can put any other string that identifies the device, for example its hostname, and instead of ''192.168.1.3'' you should provide the IP address of the node.
 +
 +There is no need to restart anything, the Munin master is a process executed from cron, not a daemon. You just have to wait about 5 minutes for the next cron invocation and check the HTML output by opening ''file:///var/cache/munin/www/index.html'' in a browser.
 +
 +This directory contains static HTML output that can be either viewed locally or served using any HTTP server. In case of problems the master logs are available at ''/var/log/munin/munin-update.log'', and the logs of a node at ''/ffp/var/log/munin/munin-node.log''.
 +
 +You can see a sample output from the Munin master at [[http://munin.ping.uio.no/|the demo installation]]. If you want to learn more about Munin, spend some time reading [[http://munin-monitoring.org/wiki/Documentation|the documentation]].

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