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

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

:Author: Stephane Thiell, <sthiell@stanford.edu>
:Date:   2019-12-01
:Copyright: GNU Lesser General Public License version 2.1 or later (LGPLv2.1+)
:Version: 1.8.3
:Manual section: 5
:Manual group: ClusterShell User Manual


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

The ClusterShell library obtains its node groups configuration from the
following sources in the following order:

 1. user configuration file (*$XDG_CONFIG_HOME/clustershell/groups.conf*)
 2. local pip user installation (*$HOME/.local/etc/clustershell/groups.conf*)
 3. system-wide configuration file (*/etc/clustershell/groups.conf*)

If no *groups.conf* is found, group support will be disabled.

Additional configuration files are also read from the directories set by the
confdir option, if present.  See the ``confdir`` 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").

confdir
  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 (except the one that defines the
  default group source). The variable *$CFGDIR* is replaced by the path of the
  highest priority configuration directory found (where groups.conf resides).
  The default confdir value enables both system-wide and any installed user
  configuration (thanks to *$CFGDIR*). Duplicate directory paths are ignored.

autodir
  Optional list of directories where the ClusterShell library should look for
  **.yaml** files that define in-file group dictionaries. No need to call
  external commands for these files, they are parsed by the ClusterShell library
  itself.  Multiple group source definitions in the same file is supported. The
  variable *$CFGDIR* is replaced by the path of the highest priority
  configuration directory found (where groups.conf resides). The default
  confdir value enables both system-wide and any installed user configuration
  (thanks to *$CFGDIR*). Duplicate directory paths 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.
cache_time
  Number of seconds each upcall result is kept in cache, in memory only.
  Default is 3600 seconds. This is useful only for daemons using nodegroups.

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

In addition to context-dependent $GROUP and $NODE variables described above, the
two following variables are always available and also replaced before executing
shell commands:

* *$CFGDIR* is replaced by groups.conf highest priority base directory path
* *$SOURCE* is replaced by current source name

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. Each
result is kept for a limited amount of time. See cache_time option to tune
this behaviour.


EXAMPLES
========

Simple configuration file for local groups and slurm partitions binding.

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

| [Main]
| default: local
| confdir: /etc/clustershell/groups.conf.d $CFGDIR/groups.conf.d
| autodir: /etc/clustershell/groups.d $CFGDIR/groups.d
| 
| [local]
| map: sed -n 's/^$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 node groups configuration file.

*/etc/clustershell/groups.conf.d/*
  Recommended directory for additional configuration files.

*/etc/clustershell/groups.d/*
  Recommended directory for *autodir*, where native group definition files
  (.yaml files) are found.

*$XDG_CONFIG_HOME/clustershell/groups.conf*
  Main user groups.conf configuration file. If $XDG_CONFIG_HOME is not defined,
  *$HOME/.config/clustershell/groups.conf* is used instead.

*$HOME/.local/etc/clustershell/groups.conf*
  Local groups.conf user configuration file (default installation for pip --user)


SEE ALSO
========

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

http://clustershell.readthedocs.org/
