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PSICK: The Infrastructure Puppet module

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This is the PSICK (Puppet Systems Infrastructure Construction Kit) module.

It is what we call an Infrastructure Puppet module, as it can be used for most common systems configurations.

It provides:

  • Solid management of classification. Entirely hiera driven.
  • An integrated set of profiles for common systems management activities
  • A growing number flexible set of tp profiles for applications
  • Safe and easy to be integrated in existing setups, cohexists with other modules
  • It allows expandibility and customisability by design.
  • Entirely Hiera driven: In practice a DSL to configure infrastructures

It can be used together with the PSICK control-repo or as a strandalone module, just:

include psick

This doesn't do anything at all, by default, but is enough to let you manage everything via Hiera.

In the following examples we will use Hiera YAML files, but any backend can be used: psick is a normal, even if somehow unusual, Puppet module, with classes (a lot of them) whose params can be set as Hiera data, defines, templates, files, fuctions, custom data types etc.

Check the default PSICK hiera data module for various usage examples.

Do You Speak Psick?

Psick "language" has the syntax of any Hiera supported backend (here we use YAML), and the semantic you are going to discover here.

The module provides 3 major features:

  • Structured cross-os, staged classification
  • Base profiles for common system configurations
  • Standardised and multifunctional tp profiles for applications


Psick can manage the whole classification of the nodes of an infrastructure. It can work side by side and External Node Classifier, or it can totally replace it.

All you need is to include the psick class and define, using ${::kernel}_class parameters, which classes to include in a node in different phases.

Psick provides 4 phases, managed by the relevant subclasses:

  • firstrun, optional phase, in which the resulting catalog is applied only once, at the first Puppet run. After a reboot can optionally be triggered and the real definitive catalog is applied.
  • pre, prerequisites classes, they are applied in a normal catalog run (that is, always except in the very first Puppet run, if firstrun is enabled) before all the other classes.
  • base, base classes, common to all the nodes (but exceptions can be applied), applied in normal catalog runs after the pre classes and before the profiles.
  • profiles, exactly as in the roles and profiles pattern. The profile classes that differentiate nodes by their role or function. Profiles are applied after the base classes are managed.

An example of configurations, both for Linux and Windows nodes that use all the above phases:

# First run mode must be enabled and each class to include there explicitely defined:
psick::enable_firstrun: true
  hostname: psick::hostname
  packages: psick::aws::sdk
  hostname: psick::hostname
  packages: psick::aws::sdk

# Pre and base classes, both on Linux and Windows
  puppet: ::puppet
  dns: psick::dns::resolver
  hostname: psick::hostname
  hosts: psick::hosts::resource
  repo: psick::repo
  sudo: psick::sudo
  time: psick::time
  sysctl: psick::sysctl
  update: psick::update
  ssh: psick::openssh::tp
  mail: psick::postfix::tp
  mail: psick::users::ad

  hosts: psick::hosts::resource
  features: psick::windows::features
  registry: psick::windows::registry
  services: psick::windows::services
  time: psick::time
  users: psick::users::ad

# Profiles for specific roles (ie: webserver)
  webserver: apache
  webserver: iis

The each key-pair of these $kernel_classes parameters contain an arbitrary tag or marker (users, time, services, but could be any string), and the name the class to include.

This name must be a valid class, which can be found in the Puppet Master modulepath (so probably defined in your control-repo Puppetfile): you can use any of the predefinied Psick profiles, or your own local site profiles, or directly classes from public modules and configure them via Hiera in their own namespace.

To manage exceptions and use a different class on different nodes is enough to specify the alternative class name as value for the used marker (here 'ssh'), in the appropriate Hiera file:

  ssh: ::profile::ssh_bastion

To completely disable on specific nodes the usage of a class, included in a general hierarhy level, set the class name to an empty string:

  ssh: ''

This is the classification part, since it's based on class parameters, it can be managed with flexibility via Hiera and can cohexist (even if this might not be an optimal choice) with other classifications methods.

The pre -> base -> profiles order is strictly enforced, so we sure to place your class in the most appropriate phase (even if functionally they all do the same work: include the specified classes) and, to prevent dependency cycles, avoid to set the same class in two different phases.

Psick tp profiles

Psick provides out of the box profiles, based on (Tiny Puppet, to manage common applications. They can replace or complement component modules when applications can be managed via packeages, services and files.

They have generated from a common template so have standard parameters, and are always called psick::$app::tp.

For example to configure Openssh both client and server settings we can write something like:

# By including the psick::openssh::tp profile we install Openssh via tp
  ssh: 'psick::openssh::tp'

# To customise the configuration files to manage at their options:
    openssh: # The openssh main configuration file
      template: 'profile/openssh/sshd_config.erb'
    openssh::ssh_config # The /etc/ssh/ssh_config file
      epp: 'profile/openssh/ssh_config.epp'

# To manage the variables referenced in the used templates (the have to map the same keys):
  AllowAgentForwarding: yes
  AllowTcpForwarding: yes
  PasswordAuthentication: yes
  PermitEmptyPasswords: no
  PermitRootLogin: no

Similary we could manage postfix with data like:

  mail: 'psick::postfix::tp'

# To customise the configuration files to manage at their options:
    postfix: # Postfix's
      template: 'profile/postfix/' #
      epp: 'profile/postfix/'

Psick base profiles

Basides tp profiles, Psick features a large set of profiles for common baseline configurations.

Some of them are intended to be used both on Linux and Windows, others are more specific.

Here follows documentation on how to manage different common system configurations:

Applications profiles

For some applications, besides standard tp profiles, there are dedicated profile classes and defines. Here's a list:

Main variables and common paraters

The main psick class manages classification (it includes psick::pre, psick::base, psick::profiles and eventually psick::firstrun classes, from where classes are included based on Hiera data) and exposes some parameters which can be used by other psick profiles.

Parameters in main psick class used by other psick profiles

Some of psick class' parameters are used as defaults for all tp profiles and most of the base ones.

They are as follows, with their default values.

Define if to actually manage any resource. This setting is the default entry point for the manage paramenter on each psick class.

Boolean $manage            = true

If to manage automatically prerequisites for the used profiles. This affects tp::install and other resources. Set to false, globally or in specific profiles, to cope with duplicated resources errors, in case same prerequisites are requested by more profiles.

Boolean $auto_prereq       = true

If to use the noop() function for all the classes included in this module. This setting is the default for all the psick classes, and can be overridden in each of them. When true the value of the parameter noop_value is passed to the noop() function.

Boolean $noop_manage       = false

The value to pass to the noop function when $noop_manage is true. This value is the default, which can be overridden, in each psick class.

Boolean $noop_value        = false # No-noop is enforced on the class and overrides any noop settings
Boolean $noop_value        = true  # Noop is enforced on the class

Special parameters in main psick class

A generic, by default empty, hash of custom settings to use as needed in any class included by psick. No psick profile is using this.

Hash $settings             = {}

An hash of different endpoints for different infrastructure services (which may be referenced in different classes). Currently used in psick::proxy

Hash $servers              = {}

An hash that configures the default resource defaults for tp::install, tp::conf and tp::dir defines. Is honoured by the above tp defines in any class included via psick.

Hash $tp                   = {} # Defaults in data/common.yaml

An hash to configure firewall related settings.

Hash $firewall             = {} # Defaults in data/common.yaml

An hash to configure monitor related settings.

Hash $monitor              = {} # Defaults in data/common.yaml

A parameter that disables forced ordering of the classes included in psick different phases (pre, base, profiles). Set this to false when you can dependency cicles between classes included via psick which you are not able to manage via proper psick classification. If set to false classes included in pre might not be actually applied before the other ones.

Boolean $force_ordering    = true

Common parameters in psick base and tp profiles

Some other parameters can be found in psick profiles:

Generic hash of options which can be used in templates evaluated in the relevant profile. It's looked up in deep merge mode and in some profiles in can be merged with local default settings. In erb templates the keys used in the $options_hash can be generally referred with <%= @options['key'] %>, with the $options var being the merge of a local $options_default + $options_hash.

Hash            $options_hash             = {}

If to install or remove the relevant profile resources (can be present, absent, installed or a version number):

Psick::Ensure   $ensure                   = 'present'

What module to use to manage the relevant profile application. This is present is some base profiles. The default is to use local psick resources (usually a tp profile), some profiles have integrations with different common public modules.

String          $module                  = 'psick'


An opinionated, integrated, extendable Puppet infrastructure module.






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