Munin


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                               Table of Contents


* Background
* The_Node

  o munin-node
  o Scripts
  o File_locations

* The_Server

  o munin.conf
  o munin-update
  o munin-graph
  o munin-html
  o munin-limits
  o munin-nagios
  o File_locations


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Background

Munin is a server/node pair that graphs, htmlifies and optionally sends out
notifications about data it gathers. It's designed to let it be easy to graph
new datasources.

The Node


munin-node

Munin-node is a perlscript listening to port 4949 using the Net::Server Perl
module. It reads all the scripts in /etc/munin/plugins (or CONFDIR/plugins/, to
be more spesific) on startup. The node accepts these commands:


  nodes
      List availbale nodes

  list [node]
      list available scripts for [node]

  config <script>
      output configuration for <script>

  fetch <script>
      output script value <script>

  version
      Output version string

  quit
      disconnect


Scripts

These scripts can be in your language of choice: bash, perl, python, C, or
anything else that your system can execute. The scripts can be run in several
modes, the important ones being without parameters, and with the "config"-
parameter. When run with "config" as parameter, the script should output the
configuration of the graph. An example with the "load" graph, which has one
field (also called "load"):

  jo@yes:~$ ./load config
  graph_title Load average
  graph_args --base 1000 -l 0
  graph_vlabel load
  graph_scale no
  load.label load
  load.warning 10
  load.critical 120

The plugin can output quite a few options:


  graph_title
      The title of the graph, defaults to the servicename.

  create_args
      If set, the arguments will be passed on to rrdcreate.

  graph_args
      If set, the arguments will be passed on to rrdgraph.

  graph_width
      Sets the width (in pixels) of the graph. Defaults to 400.

  graph_height
      Sets the height (in pixels) of the graph. Defaults to 175.

  graph_order
      In witch order to draw the fields. Can also include path aliases on the
      form alias=domain;host:graph.datasource. See further down for details.

  graph_vlabel
      Y-axis label of the graph.

  graph_vtitle
      Y-axis label of the graph. NOTE: Deprecated, use graph_vlabel. If the
      graph is COUNTER or DERIVE based, the variable ${graph_period} can be
      used to access the current scale (second, minute, hour, day).

  graph_info
      A description of the graph contents.

  graph_total
      If set, summarise all the datasources' values and use the value of
      graph_total as a label.

  graph_scale
      Default on. If set, enables scaling of awg/min/max/cur values.

  graph_period
      Default "second". Set to "minute" to scale (almost) all graphs that are
      COUNTER or DERIVE based, to show data per minute instead of per second.

  graph_sums
      Creates two additional graphs for services using COUNTER or DERIVE
      fields. The new graphs show values per hour and day. NOTE: This feature
      requires rrdtool version 1.0.39 or above.

  graph
      Set to "yes" or "no". Decides wether to draw the graph. Defaults to
      "yes".

  update
      Set to "yes" or "no". Decides wether munin-update should fetch data for
      the graph. Defaults to "yes".

  host_name
      Override which host name this plugin is run for. Ugly - see further down
      on how to do this in the node configuration files instead, which is more
      elegant.

  {field}.label
      REQUIRED. Name of the datasource. You can have many datasouces in one
      graph.

  {field}.cdef
      RPN-expression. Modify the values before graphing. See the FAQ for
      examples.

  {field}.draw
      What to draw from the data source: AREA, LINE1-3. Defaults to LINE2.

  {field}.graph
      Set to "no" or "yes. Decides wether to graph the data source. Defaults to
      yes.

  {field}.max
      Maximum value. If the fetched value is above "max", it will be discarded.

  {field}.min
      Minimum value. If the fetched value is below "min", it will be discarded.

  {field}.negative
      Name of field to 'mirror' on the opposite side of zero. See the FAQ for
      examples.

  {field}.skipdraw
      Disables drawing of datasource. NOTE: Deprecated - use {field}.graph
      instead.

  {field}.info
      A description of the field.

  {field}.type
      Type of datasource, COUNTER, ABSOLUTE, DERIVE and GAUGE, defaults to
      GAUGE. Read "man rrdcreate" for more info.

  {field}.line
      Draw a line (HRULE) associated with the field. Format is <value>[:colour
      [:label]]. The default colour is the same as the field colour, or red if
      it's a single-field graph. Default label is unset.

  {field}.warning
      Used by munin-nagios. Can be a max value or a range sepereated by colon.
      E.g. "min:", ":max", "min:max", "max".

  {field}.critical
      Same as above.

{field} is limited to 19 characters, and the characters [a-zA-Z0-9_]. The fist
character cannot be a number.
Without options the script should only give out {name}.value (value):

  jo@yes:~$ ./load
  load.value 0.41

All scriptnames containing other characters than alphanumerics, "-", "_", and
".", or starting with "." will be skipped.
To run a plugin as a specific user and/or group, create a file in the plugin
configuration dir (default is CONFDIR/plugin-conf.d/). This file is parsed as
munin-node starts up. It can contain the following options:


  [<plugin-name>]
      The following lines are for plugin-name.

  user <username|userid>
      Run plugin as this user. Only works if munin-node is run as root.

  group <groupname|groupid>[, <groupname|groupid>] [...]
      Run plugin as this group. If group is inside paranthesis, don't croak if
      it's nonexistant. Only works if munin-node is run as root.

  command <command>
      Run command instad of plugin. "%c" will be expanded to what would
      otherwise have been run. E.g. "command sudo -u root %c". Nice to avoid
      running munin-node as root.

  allow <regex>
      Allow hosts matching regex to run this plugin.

  deny <regex>
      Deny hosts matching regex from running this plugin.

  timeout <seconds>
      Use a timeout of <seconds> seconds instead of the default timeout of 10
      seconds, when running this plugin.

  env.<var> <contents>
      Set the environment variable var to contents before running the plugin.

Example:

  [exim_mailstats]
  group mail

  [cps_*]
  user root

  # Will cause the variable "mysqlopts" to be set inside the plugins
  [mysql_*]
  env.mysqlopts --user foo --password fii


File locations

According to FHS, this is where you should place the files.

System package (Debian, RedHat, maybe others)



  CONFDIR
      /etc/munin/

  SBINDIR
      /usr/sbin/

  LIBDIR
      /usr/share/munin/

  STATEDIR
      /var/run/munin/

  LOGDIR
      /var/log/munin/


Independent install (tarball)



  CONFDIR
      /etc/opt/munin/

  SBINDIR
      /opt/munin/sbin/

  LIBDIR
      /opt/munin/lib/

  STATEDIR
      /var/run/munin/

  LOGDIR
      /var/log/munin/


The Server

The server runs a cronjob as the user munin every 5 minutes. The cronjob runs
munin-update,munin-limits,munin-graph and munin-html one by one. All scripts
creates a lockfile in @@STATEDIR@@. Everytime a script starts, it checks if the
pid in the lockfile is alive before starting.

munin.conf

This is the configuration-file for all serverscripts.

  #Configfile for munin
  dbdir       /var/lib/munin/
  htmldir     /var/www/munin/
  logdir      /var/log/munin
  rundir      /var/run/munin/

  #To send email notifications
  contact.email.command mail -s "Notification from Munin" fnord@fnord.com
  #To notify nagios
  contact.nagios.command /usr/bin/send_nsca -H nagios-server.fnord.com -c /etc/
  send_nsca.cfg

  #
  # Edit and uncomment the following to start surveilance
  #
  #[machine.fnord.com]
  #  address localhost

Explaination:


  dbdir
      Rootdir for alle rrd-files (files go into <dbdir>/<domain>/)

  htmldir
      Where the png's and htmlfiles end up

  logdir
      Where to put logs

  rundir
      Where to put state files

  htaccess
      The default htaccessfile

  tmpldir
      Where the templates reside

  graph_strategy
      Set to "cron" to draw the graphs periodically via cron every 5 minutes.
      Set to "cgi" to draw on-demand. (default cron)

  cgiurl
      URL to the directory where the CGI scripts (for the time being only one)
      doing the graphing (if graph_strategy is "cron"). (default /cgi-bin)

  cgiurl_graph
      URL to the CGI script doing the graphing (if graph_strategy is "cron").
      (default ${cgiurl}/munin-cgi-graph)

  fork
      If set, run updates of several hosts simultaneously. (default yes)

  max_processes
      Set max number of simultaneous Munin processes.

  nsca*
      Nagios options. See seperate section. Deprecated, use contacts instead.

  contact.*
      Set contact information. See separate section.

  contacts
      Set which contact entries to use ("none" for no contacts). Default is all
      contact entries existing under "contact" tree.

  domain_order
      Change the order of domains. (Default is alphabetically sorted.)

  local_address
      Set the local address to be used for connecting to the nodes.

  [foo.com;machine.dom.ain]
      Add machine.dom.ain to group foo.com.

  [machine.dom.ain]
      Add machine.dom.ain to group dom.ain. (A short form of
      [dom.ain;machine.dom.ain].)

 To add a new node, just put in a new section and add the address option.
Group-level options


  node_order
      Changes order of nodes in a group. (Default is alphabetically sorted.)

  local_address
      Set the local address to be used for connecting to the nodes in the
      group.

  compare
      Generate node comparisons for the nodes in this group.

  contacts
      Set which contact entries to use for nodes in this group. Default is all
      contact entries existing under "contact" tree.

 Node-level options


  address
      Set the node address

  local_address
      Set the local address to be used for connecting to the node.

  port
      Set node port number (default 4949)

  use_node_name
      Set to "yes" or "y" to force getting all the default plugins from a node.
      Good for hosts which changes hostname (e.g. laptops).

  use_default_name
      Set to "yes" or "y" to force getting all the default plugins from a node.
      Good for hosts which changes hostname (e.g. laptops). NOTE: Deprecated.
      Use use_node_name instaed.

  contacts
      Set which contact entries to use for this node. Default is all contact
      entries existing under "contact" tree.

 Field-level options


  sum
      Summarise other fields. See the FAQ for how to use this.

  stack
      Stack other fields. See the FAQ for how to use this.

  +++
      Check the node configuration (further up) for everything else.


munin-update

Munin-update reads munin.conf, searches for nodes, and connect to the munin-
nodes using the address-field. When connected it will run the list-command to
fetch available scripts, then it will run config for each script. This
configuration will expand in the datafile and rdd-databases will be created.
Already expanded configuration will be skipped. Then munin-update runs through
it's newly modified configuration file and runs fetch on all scripts.

munin-graph

Munin-graph reads /etc/munin/munin.conf and graphs all services unless
[service].graph no. The following options are available in the configuration

limited to 19 characters

  [service].graph_title
      The title of the graph

  [service].graph_order
      Which order to graph the lines.

  [service].graph_args
      Extra arguments to the graph

  [field].label
      REQUIRED, the name of the value to be graphed,

  [field].type
      Type of value. COUNTER, GAUGE, defaults to GAUGE. NOTE: When GAUGE is
      used, only "snapshots" of every 5 minutes are recorded. Peaks in-between
      updates will not be graphed. When you use COUNTER, the numbers are
      averaged out over the past 5 minutes, so short peaks will show up as
      substancially lower than they were.


munin-html

Munin-html creates the html-pages for the graphs.
Usefull configuration in the server.conf file is:
node_order [node1] [node2] ....
In which order the nodes should be listed, defaults to sorted. This is a
domain-level option.
domain_order [domain1] [domain2] ....
In which order the domains should be listed, defaults to sorted. This is a top-
level option.
category_order_order [category1] [category2] ....
In which order the categories should be listed, defaults to sorted. This is a
node-level option.
service_order_order [service1] [service2] ....
In which order the services should be listed, defaults to sorted. This is a
node-level option.

munin-limits

Munin-limits is a script to send an alert to a set of contacts. Munin-limits
operates with three states -- ok, warning and critical.

The quick and easy way

For most people, the following line will do all the work:

  contact.email.command mail -s "Munin-notification for ${var:group} :: ${var:
  host}" your@email.address.here

This entry will use the default text entry, which should probably suite most
people. If you also use Nagios, try swapping all the nsca* parameters for:

  contact.nagios.command /usr/bin/send_nsca -H your.nagios-host.here -c /etc/
  send_nsca.cfg


Defining contacts

There are some top-level options available in munin.conf:


  contact.<contact>.command <command>
      Define which command to run. Mandatory for each contact. The command can
      start with "> " (greater than space) to create/empty a file and write to
      it, or ">> " (greater than greater than space) to append to a file.

  contact.<contact>.text <text>
      Text to pipe into the command. Default is the text in
      contact.default.text, which is hardcoded (but can be overridden).
      contact.nagios.text also has a short hardcoded default suitable for
      transmission via nsca to Nagios.

  contact.<contact>.max_messages <num>
      Close (and reopen) command after <num> messages.

  contact.<contact>.always_send <states>
      Always send messages with a state that is mentioned in <states>. This
      only works for "warning" and "critical" states. <states> is a space
      delimited list.

  contacts <contact-list>
      A list of the available contacts to use by default. Defaults to all
      contacts with a command definition. Can be set on every level -- top-
      level, domain-level, node-level and service-level.


Command and text definitions

When defining the command and text entries, a number of variables are available
for expansion.


  ${var:<variable>}
      For example ${var:graph_title}. All variables from the plugin are
      available, as well as the following:


        numofields
            Number of OKs in the service.

        numfofields
            Number of new OKs (which were not OK on the last run) in teh
            service.

        numwfields
            Number of warnings in the service.

        numcfields
            Number of criticals in the service.

        ofields
            Fields in the service with an OK state.

        fofields
            Fields in the service which just went to OK state.

        wfields
            Fields in the service with a state of warning.

        cfields
            Fields in the service with a state of critical.

        fields
            All fields in the service.

        worst
            The worst state of all the fields in the plugin.

        worstid
            0 for ok, 1 for warning, 2 for dcritical.

        wrange
            The warning range of the field.

        crange
            The critical range of the field.

        host
            The hostname.

        group
            The name of the group/domain.

        plugin
            The name of the plugin.

        value
            Current value of the field.


  ${if:[!]<field> <text>}
      Include <text> only if <field> is not 0 or a zero length string. Reverse
      meaning if the "!" is included.

  ${loop[<sep>]:<list> <text>}
      Print <text> once for each element of the space separated <list>.
      Separate the <text> additions with the contents of [sep] if it exists
      (note that the < and > should be included). Example: ${loop<, >:fields $
      {var:label} is ${var:state}}.


Limit definitions in the plugin or munin.conf

A contact is only contacted if a value falls outside the .warning or .critical
fields in your configuration or plugin scripts. The value for these field can
be a single maxvalue or a colonseperated range

  processes.warning 10:300
  processes.critical 5:500

A value lower than 10 or higher then 300 will result in a warning to nagios, a
value lower than 5 or higher than 500 will result in a critical.
Other usefull ranges:

  [field].warning :400

is equal to:

  [field].warning 400

Only warn if lower than 300:

  [field].warning 300:

When a service contains .critical or .warning it will chech it's status agains
the last fetched value. Any change in the state (ok, warning, critical) will
cause a notification to be sent.

munin-nagios

NOTE: As of version 1.1.5, munin-nagios is replaced by munin-limits. Munin-
nagios is a optional script to send a passive alert to a nagios-server. For
this to work, you need a nagios-nsca server, a working send_nsca configuration
and the following configuration in /etc/munin/munin.conf:

  nsca          /usr/bin/send_nsca
  nsca_config   /etc/nagios/send_nsca.cfg
  nsca_server   [nsca-server]

Then add .warning and .critical fields in your configuration or directly into
you plugin scripts. The value for these field can be a single maxvalue or a
colonseperated range

  processes.warning 10:300
  processes.critical 5:500

A value lower than 10 or higher then 300 will result in a warning to nagios, a
value lower than 5 or higher than 500 will result in a critical to nagios
Other usefull ranges:

  [service].warning :400

is equal to:

  [service].warning 400

Only warn if lower than 300:

  [service].warning 300:

When a service contains .critical or .warning it will chech it's status agains
the last fetched value. If it's ok, a "{service}.ok" file will be created in
the $dbdir/$domain directory. If the value is not ok. This file will be removed
and munin-nagios will update nagios every 5 minutes untill the value is ok and
a new ".ok" file will be created.

File locations

According to FHS, this is where you should place the files.

System package (Debian, RedHat, maybe others)



  CONFDIR
      /etc/munin/

  SBINDIR
      /usr/sbin/

  LIBDIR
      /usr/share/munin/

  STATEDIR
      /var/run/munin/

  LOGDIR
      /var/log/munin/

  DBDIR
      /var/lib/munin/


Independent install (tarball)



  CONFDIR
      /etc/opt/munin/

  SBINDIR
      /opt/munin/sbin/

  LIBDIR
      /opt/munin/lib/

  STATEDIR
      /var/run/munin/

  LOGDIR
      /var/log/munin/

  DBDIR
      /var/opt/munin/