deferlib
Table of Contents
Description
Control your resources parameters from client side without creating useless facts.
Provides functions library to use to get values for resource parameters from files/command executed on agent side (deferred), providing way to control resources from agent host local things without creating facts that executes on all servers.
Setup
Setup Requirements
Puppet agent/server >= 7
Beginning with deferlib
deferlib provides functions to use to modify resource parameters from host runnning puppet agent (instead of using facts for example).
Example:
# do not restart cron when maintenance flag file exists putting ensure to undef
# => function to read: unless file /etc/maintenance exists ensure running, (else ensure undef)
service { 'cron':
ensure => deferlib::unless_file('/etc/maintenance', 'running'),
}
# noop mode when maintenance preventing starting service during operation
service { 'cron':
ensure => 'running',
noop => deferlib::if_file('/etc/maintenance', true, false),
}
Usage
functions available:
deferlib::if_file()
deferlib::if_file(file, value, [default])
Description:
returns value if file exits else returns default (default: [])
Parameters:
file : path to file to check existence
value : value returned if file exists
default : value returned if file does not exist (default [])
Example:
# stop cron when cron_stop flag file exists
# => function to read: if file /etc/cron_stop exists ensure stopped else ensure running
service { 'cron':
ensure => deferlib::if_file(/etc/cron_stop', 'stopped', 'running'),
}
deferlib::unless_file()
deferlib::unless_file(file, value, [default])
Description:
returns value if file does not exits else returns default (default: [])
Parameters:
file : path to file to check existence
value : value returned if file does not exist
default : value returned if file exists (default [])
Example:
# do not restart cron when maintenance flag file exists putting ensure to undef ([])
# => function to read: unless file /etc/maintenance exists ensure running, (else ensure undef)
service { 'cron':
ensure => deferlib::unless_file('/etc/maintenance', 'running'),
}
deferlib::if_cmd()
deferlib::if_cmd(cmd, value, [])
Description:
returns value if exit code of cmd is 0 else returns options[else] (default to [])
Parameters:
cmd : shell code to execute
value : value returned if exit status is 0
options : {
'else' => # value returned if exit status is not 0 (default: [])
'user' => # The user to run the command as
'group' => # The group to run the command as
'environment' => # A Hash of environment variables
}
options['environment'] : {
'<variable name>' => # value of the environement variable
...
}
Example:
# ensure cron running if isproduction returns 0
service { 'cron':
ensure => deferlib::if_cmd('/bin/isproduction', 'running', {
'user' => 'foo',
'group' => 'bar',
}),
}
deferlib::unless_cmd()
deferlib::unless_cmd(cmd, value, [])
Description:
returns value if exit code of cmd is not 0 else returns options[else] (default to [])
Parameters:
cmd : shell code to execute
value : value returned if exit status is not 0
options : Hash with optional settings
options : {
'else' => # value returned if exit status is 0 (default: [])
'user' => # The user to run the command as
'group' => # The group to run the command as
'environment' => # A Hash of environment variables
}
options['environment'] : {
'<variable name>' => # value of the environement variable
...
}
Example:
# ensure cron running unless ismaintenance returns 0
service { 'cron':
ensure => deferlib::unless_cmd('/bin/ismaintenance', 'running', {
'user' => 'foo',
'group' => 'bar',
}),
}
deferlib::cmd()
deferlib::cmd()
Description:
returns output of options[command] if exit code is 0 else returns options['else'] (default to [])
parameters:
options : Hash with parameters
options : {
'command' => # Shell code to execute
'match' => # regexp to validate output (returns default if not)
'else' => # value returned if exit code is not 0
'user' => # The user to run the command as
'group' => # The group to run the command as
'environment' => # A Hash of environment variables
}
options['environment'] : {
'<variable name>' => # value of the environement variable
...
}
Example:
# force ensure from local file content if exists, else ensure running
service { 'cron':
ensure => deferlib::cmd'({
'command' => 'cat /etc/cron_ensure',
'else' => 'running',
}),
}
# use script cron_ensure from puppet module files
service { 'cron':
ensure => deferlib::cmd({
'command' => file("${module_name}/cron_ensure"),
}),
}