=============
 groups.conf
=============

--------------------------------------------------------
Configuration file for ClusterShell external node groups
--------------------------------------------------------

:Author: Stephane Thiell, CEA DAM  <stephane.thiell@cea.fr>
:Date:   2012-03-31
:Copyright: CeCILL-C V1
:Version: 1.6
:Manual section: 5
:Manual group: ClusterShell User Manual


DESCRIPTION
===========

The ClusterShell library obtains node groups configuration options from the
system-wide configuration file */etc/clustershell/groups.conf*.
Additional configuration files are also read from the directories set by the
groupsdir option, if present.  See the ``groupsdir`` option below for further
details.

Configuration files have a format in the style of RFC 822 potentially composed
of several sections which may be present in any order. There are two types of
sections: Main and Group source:

Main
  Global configuration options. There should be only one Main section.
*Group_source*
  The *Group_source* section(s) define the configuration for each node group
  source (or namespace). This configuration consists in external commands
  definition (map, all, list and reverse).

Only *Group_source* section(s) are allowed in additional configuration files.


[Main] OPTIONS
--------------
Configuration parameters of the ``Main`` section are described below.

default
  Specify the default group source (group namespace) used by the NodeSet parser
  when the user does not explicitly specify the group source (eg. "@io").

groupsdir
  Optional list of directories where the ClusterShell library should look
  for .conf files which define group sources to use. Each file in these
  directories with the .conf suffix should contain one or more *Group_source*
  sections as documented in [*Group_source*] options below. These will be
  merged with the group sources defined in */etc/clustershell/groups.conf* to
  form the complete set of group sources that ClusterShell will use. Duplicate
  *Group_source* sections are not allowed.  Note: .conf files that are not
  readable by the current user are ignored.


[*Group_source*] OPTIONS
------------------------
Configuration parameters of each group source section are described below.

map
  Specify the external shell command used to resolve a group name into a
  nodeset, list of nodes or list of nodeset (separated by space characters or
  by carriage returns). The variable *$GROUP* is replaced before executing the
  command.
all
  Optional external shell command that should return a nodeset, list of
  nodes or list of nodeset of all nodes for this group source. If not
  specified, the library will try to resolve all nodes by using the ``list``
  external command in the same group source followed by ``map`` for each group.
list
  Optional external shell command that should return the list of all groups
  for this group source (separated by space characters or by carriage
  returns).
reverse
  Optional external shell command used to find the group(s) of a single
  node. The variable $NODE is previously replaced. If this upcall is not
  specified, the reverse operation is computed in memory by the library from
  the *list* and *map* external calls. Also, if the number of nodes to
  reverse is greater than the number of available groups, the *reverse*
  external command is avoided automatically.

When the library executes a group source external shell command, the current
working directory is previously set to the corresponding groupsdir. This
allows the use of relative paths for third party files in the command.

Each external command might return a non-zero return code when the operation
is not doable. But if the call return zero, for instance, for a non-existing
group, the user will not receive any error when trying to resolve such unknown
group.  The desired behaviour is up to the system administrator.


RESOURCE USAGE
==============

All external command results are cached in memory to avoid multiple calls.


EXAMPLES
========

Simple configuration file for local groups and slurm partitions binding.

*groups.conf*
-------------

| [Main]
| default: local
| #groupsdir: /etc/clustershell/groups.conf.d/
| 
| [local]
| map: sed -n 's/^$GROUP:\(.*\)/\1/p' /etc/clustershell/groups
| list: sed -n \'s/^\\(``[0-9A-Za-z_-]``\*\\):.*/\\1/p' /etc/clustershell/groups
| 
| [slurm]
| map: sinfo -h -o "%N" -p $GROUP
| all: sinfo -h -o "%N"
| list: sinfo -h -o "%P"
| reverse: sinfo -h -N -o "%P" -n $NODE



FILES
=====

*/etc/clustershell/groups.conf*
  System-wide external node groups configuration file.
*/etc/clustershell/groups.conf.d/*
  Recommended directory for additional configuration files.


SEE ALSO
========

``clush``\(1), ``clubak``\(1), ``nodeset``\(1)

http://clustershell.sourceforge.net/

