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MUNIN.CONF(5) Munin MUNIN.CONF(5)

NAME

munin.conf - Configuration file for the munin master

DESCRIPTION

This is the configuration file for the munin master. It is used by munin-update, munin-limits and munin-httpd.

Location in packages is usually /etc/munin/ while if compiled from source it is often found in /etc/opt/munin/.

The structure is:

1.
One general/global section
2.
Zero or more group section(s)
3.
One or more host section(s)

Group and host sections are defined by declaring the group or host name in brackets. Everything under a section definition belongs to that section, until a new group or host section is defined.

NOTE:

As the global section is not defined through brackets, it must be found prior to any group or host sections. It will not work if you place them in later sections of the config file. We recommend to use the delivered munin.conf file and adapt it to your needs.


Comments can be included by prefacing them with #. A literal # in a configuration value can be escaped with a backslash: \#. Long lines can be wrapped by ending them with \. Note that \ has no special meaning otherwise, nor do any other characters; in particular, quotes have no special meaning, so a line like contact.irc.command irc-notify "#munin-alerts" will be parsed as contact.irc.command irc-notify " unless the # is escaped.

GLOBAL DIRECTIVES

Global directives affect all munin master components unless specified otherwise.

The directory where munin stores its database files (Default: /var/lib/munin). It must be writable for the user running munin-cron. RRD files are placed in subdirectories $dbdir/$domain/

The directory shown by munin-httpd. It must be writable for the user running munin-httpd. For munin 2.0: The directory where munin-html stores generated HTML pages, and where munin-graph stores graphs.

The directory where munin stores its logfiles (Default: /var/log/munin). It must be writable by the user running munin-cron.

Directory for files tracking munin’s current running state. Default: /var/run/munin

Directories for templates used by munin-httpd (munin 2.0: munin-html) to generate HTML pages. Default /etc/munin/templates

Where to look for the static www files.

Temporary cgi files are here. It has to be writable by the cgi user (For Munin stable 2.0 usually nobody or httpd).

(Exactly one) directory to include all files from. Default /etc/munin/plugin-conf.d/

Sets the local IP address that munin-update should bind to when contacting the nodes. May be used several times (one line each) on a multi-homed host. Should default to the most appropriate interface, based on routing decision.

NOTE:

This directive can be overwritten via settings on lower hierarchy levels (group, node).


This directive determines whether munin-update fork when gathering information from nodes. Default is “yes”.

If you set it to “no” munin-update will collect data from the nodes in sequence. This will take more time, but use less resources. Not recommended unless you have only a handful of nodes.

Affects: munin-update


This directive will set how long to wait in seconds before giving up on establishing a connection to a munin node when using the munin protocol. Default is “180”.

Affects: munin-update


This directive will set the maximum amount of time in seconds the munin-update task may run. So we’ll make sure the update ended within the 5 minutes timespan needed to have complete graphs without gaps.

Do not set this value higher, unless all nodes are using ssh with munin-async. Munin-async can retrieve historical data, and if there is a big backlog, we could need more time depending on the size of the data generated by the plugin and the size of the backlog. This would also mean that we wouldn’t care to skip an update. So munin-async will get more time to retrieve the backlog data. Afterwards new data will incrementally be fetched. Default is 240.

Affects: munin-update


This directive will set the maximum amount of time in seconds the munin-update task may run 1 single node. This value can’t be bigger than timeout_fetch_all_nodes. Default is 180.

Affects: munin-update


The palette used by munin-httpd to color the graphs. The “default” palette has more colors and better contrast than the “old” palette.

The user defined custom palette used by munin-httpd to color the graphs. This option overrides the existing palette. The palette must be space-separated 24-bit hex color code.

You can choose the time reference for “DERIVE” like graphs, and show “per minute” => minute, “per hour” => hour values instead of the default “per second”.

Munin HTML templates use this variable to decide whether to use dynamic (“lazy”) loading of images with javascript so that images are loaded as they are scrolled in view. This prevents excessive load on the web server. Default is 0 (off).

Available since Munin 1.4.0. Maximum number of parallel processes used by munin-graph when calling rrdgraph. The optimal number is very hard to guess and depends on the number of cores of CPU, the I/O bandwidth available, if you have SCSI or (S)ATA disks and so on. You will need to experiment. Set on the command line with the -n n option. Set to 0 for no forking.

munin-cgi-graph is invoked by the web server up to very many times at the same time. This is not optimal since it results in high CPU and memory consumption to the degree that the system can thrash. Again the default is 6. Most likely the optimal number for max_cgi_graph_jobs is the same as max_graph_jobs.

If the automatic CGI url is wrong for your system override it here.

The max width of images in pixel. Default is 4000. Do not make it too large otherwise RRD might use all RAM to generate the images.

The max height of images in pixel. Default is 4000. Do not make it too large otherwise RRD might use all RAM to generate the images.

This option is available only in munin 2.0. In munin 2.0 graphics files are generated either via cron or by a CGI process.

If set to “cron”, munin-graph will graph all services on all nodes every run interval.

If set to “cgi”, munin-graph will do nothing. Instead graphs are generated by the webserver on demand.


This option is available only in munin 2.0. In munin 2.0 HTML files are generated either via cron (default) or by a CGI process.

If set to “cron”, munin-html will recreate all html pages every run interval.

If set to “cgi”, munin-html will do nothing. Instead HTML files are generated by the webserver on demand. This setting implies graph_strategy cgi


munin-update runs in parallel.

The default max number of processes is 16, and is probably ok for you. Should be not higher than 4 x CPU cores.

If set too high, it might hit some process/ram/filedesc limits. If set too low, munin-update might take more than 5 min. If you want munin-update to not be parallel set it to 1.


RRD updates are per default, performed directly on the rrd files. To reduce IO and enable the use of the rrdcached, uncomment it and set it to the location of the socket that rrdcached uses.

This directive sets the resolution of the RRD files that are created by munin-update.

Default is “normal”.

“huge” saves the complete data with 5 minute resolution for 400 days.

With “custom” you can define your own resolution. See the instruction on custom RRD sizing for the details.

Changing this directive has no effect on existing graphs


Define which contact command to run. See the tutorial Let Munin croak alarm for detailed instruction about the configuration.

Text to pipe into the command.

Close (and reopen) command after given number of messages. E.g. if set to 1 for an email target, Munin sends 1 email for each warning/critical. Useful when relaying messages to external processes that may handle a limited number of simultaneous warnings.

If there are alerts of the given severities, send them to this contact every time munin-limits runs, even if they haven’t changed since last time.

The name of the secure shell command to use. Can be fully qualified or looked up in $PATH.

Defaults to “ssh”.


The options for the secure shell command.

Defaults are “-o ChallengeResponseAuthentication=no -o StrictHostKeyChecking=no”. Please adjust this according to your desired security level.

With the defaults, the master will accept and store the node ssh host keys with the first connection. If a host ever changes its ssh host keys, you will need to manually remove the old host key from the ssh known hosts file. (with: ssh-keygen -R <node-hostname>, as well as ssh-keygen -R <node-ip-address>)

You can remove “StrictHostKeyChecking=no” to increase security, but you will have to manually manage the known hosts file. Do so by running “ssh <node-hostname>” manually as the munin user, for each node, and accept the ssh host keys.

If you would like the master to accept all node host keys, even when they change, use the options “-o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -o PreferredAuthentications=publickey”.


Change the order of domains/groups. Default: Alphabetically sorted

GROUP DIRECTIVES

If you want to set directives on the group level you have to start the group section with the groups name in square brackets.

[mygroup.mydomain]


Changes the order of nodes in a domain. Default: Alphabetically sorted.

A list of contacts used by munin-limits to report values passing the warning and critical thresholds.

If set to something else than “no”, names a list of contacts which should be notified for this node. Default is “no” and then all defined contacts will get informed when values go over or below thresholds.


NOTE:

This directive can be overwritten via settings on lower levels of the hierarchy (node, plugin).


NODE DEFINITIONS

Node definitions can have several types. In all forms, the definition is used to generate the node name and group for the node, and the following lines define its directives. All following directives apply to that node until another node definition or EOF.

When defining a nodename it is vital that you use a standard DNS name, as in, one that uses only “a-z”, “-”, and “.”. While other characters can be used in a DNS name, it is against the RFC, and Munin uses the other characters as delimiters. If they appear in nodenames, unexpected behavior may occur.

The simplest node definition defines the section for a new node by simply wrapping the DNS name of the node in brackets, e.g. [machine1.example.com]. This will add the node machine1.example.com to the group example.com.

The next form of definition is used to define the node and group explicitly. It follows the form [example.com;machine1.sub.example.com]. This adds the node machine1.sub.example.com to the group example.com. This can be useful if you have machines you want to put together as a group that are under different domains (as in the given example). This can also solve a problem if your machine is example.com, where having a group of com makes little sense.

A deeper hierarchy can be specified by using a list of groups, separated with “;”. For example: [site1;customer2;production;mail.customer2.example.org].

NODE DIRECTIVES

These are directives that can follow a node definition and will apply only to that node.

Specifies the host name or IP address, with an optional scheme.

Permitted schemes are “munin://”, “ssh://” or “cmd://”. If no scheme is specified, the default is “munin://”

The “ssh://” and “cmd://” schemes take arguments after the URL. See Address schemes for examples.


The port number of the node. Ignored if using alternate transport. Default is “4949”.

If “yes”, when querying the node, the master will trust the name the node reports for itself, and ask for plugins associated with that name. This means that it will fetch metrics from plugins running on the node itself, which is usually what you want.

If “no”, the master will ignore the name reported by the node when it connects, and ask for plugins associated with the name configured in munin.conf. This is generally what you want when the node is collecting metrics on behalf of other systems, e.g. via SNMP plugins.

When you have one node that collects metrics from several systems (e.g. querying multiple routers via SNMP), it’s common to have multiple entries for it in munin.conf with the same address, different node names, and use_node_name no.

See also Using SNMP Plugins.


Used by munin-limits.

If set, changes the name by which the node presents itself when warning through munin-limits.


NOTE:

This directive can also be used on hierarchy level plugin to change the name by which the plugin presents itself when warning through munin-limits.


Available since Munin 3.0.

If set, ignore any unknown values reported by the node. Allowed values are “yes” and “no”. Defaults to “no”.

Useful when a node is expected to be off-line frequently.


Fetch data from this node with munin-update? Allowed values are “yes” and “no”. Defaults to “yes”.

If you make a virtual node which borrow data from real nodes for aggregate graphs, set this to “no” for that node.


PLUGIN DIRECTIVES

These directives follow a node definition and are of the form “plugin.directive <value>”.

Using these directives you can override various directives for a plugin, such as its contacts, and can also be used to create graphs containing data from other plugins.

Override the title of a specific graph.

Override the category of a specific service.

The graph height for a specific service. Default is 200.

Affects: munin-httpd.


The graph width for a specific service. Default is 400.

Affects: munin-httpd.


For a complete list see the reference of global plugin attributes.

FIELD DIRECTIVES

These directives follow a node definition and are of the form “plugin.field <value>”.

Using these directives you can override values originally set by plugins on the nodes, such as warning and critical levels or graph names.

The value at which munin-limits will mark the service as being in a warning state. Value can be a single number to specify a limit that must be passed or they can be a colon separated pair of numbers defining a valid range of values.

Affects: munin-limits.


The value at which munin-limits will mark the service as being in a critical state. Value can be a single number to specify a limit that must be passed or they can be a colon separated pair of numbers defining a valid range of values.

Affects: munin-limits.


For a complete list see the reference of plugin data source attributes.

EXAMPLES

Three nodes

A minimal configuration file, using default settings for everything, and specifying three nodes.

[mail.example.com]
address mail.example.com
[web.example.com]
address web.example.com
[munin.example.com]
address localhost


Virtual node

A virtual node definition. Disable update, and make a graph consisting of data from other graphs.

[example.com;Totals]
update no
load.graph_title Total load
load.sum_load.label load
load.sum_load.stack mail=mail.example.com web=web.example.com munin=munin.example.com


Address schemes

The scheme tells munin how to connect to munin nodes.

The munin:// scheme is default, if no scheme is specified. By default, Munin will connect to the munin node with TCP on port 4949.

The following examples are equivalent:

# master: /etc/munin/munin.conf.d/node.example.conf
[mail.site2.example.org]
address munin://mail.site2.example.org
[mail.site2.example.org]
address munin://mail.site2.example.org:4949
[mail.site2.example.org]
address mail.site2.example.org
[mail.site2.example.org]
address mail.site2.example.org
port    4949


To connect to a munin node through a shell command, use the “cmd://” prefix.

# master: /etc/munin/munin.conf.d/node.example.conf
[mail.site2.example.org]
address cmd:///usr/bin/munin-async [...]


To connect through ssh, use the “ssh://” prefix.

# master: /etc/munin/munin.conf.d/node.example.conf
[mail.site2.example.org]
address ssh://bastion.site2.example.org/bin/nc mail.site2.example.org 4949
[www.site2.example.org]
address ssh://bastion.site2.example.org/bin/nc www.site2.example.org 4949


NOTE:

When using the ssh:// transport, you can configure how ssh behaves by editing ~munin/.ssh/config. See the ssh transport configuration examples.


SEE ALSO

See munin for an overview over munin.

example-transport-ssh

AUTHOR

The Munin project and its contributors, Stig Sandbeck Mathisen

COPYRIGHT

2012-2022, The Munin project and its contributors

February 10, 2022 2.1