Puppet Roles and Hiera Parameter Hierarchy

This is a design pattern to implement roles like Chef and to separate class parameters into a parameter hierachy also like chef.

The roles can be either set on the individual server using custom facts or on the puppetmaster in the hieradata for the node. If set in the puppetmaster hierdata this takes precedence.

This will work with both masterless puppet (ie puppet apply command) or with a puppet master (ie puppet agent command)

Setting the Roles

On the individual server set the Facter variable role_name1 to role_name4. For example:

  export FACTER_role_name1=base
  export FACTER_role_name2=webserver 
  

On the puppetmaster set the roles in the nodes\.yaml file using values role::role_name1 to role::role_name4 For example file hieradata/nodes/ubuntu-server.yaml contains

  ---
  role::role_name1:  base
  role::role_name2:  webserver

Application Module Name Prefix

A common design pattern is to prefix your application puppet module names with a company name prefix. This allows for separation of library modules from application modules or classes. This separates them from standard library modules that can be specified using puppet librarian or downloaded from puppetforge or github which should then NOT be customized.

To achieve this set the Direct Module Prefix in the site manifest

 class { 'role' : prefix => 'mycompany' }
 

This will result in calls to modules mycompany_base and mycompany_webserver. NOTE: For compatibility with previous versions of role you can set the separator char to underscore in the site manifest

 class { 'role' : prefix => 'mycompany', separator => '-'  }

Module Calling

Setting the roles to base and webserver will result in calls to the modules called base and webserver and running the init.pp manifest. It is possible to specify a class to called different to the init.pp by setting the role_manifestX to the manifest name.

for example

export FACTER_role_name1=base
export FACTER_role_name2=webserver
export FACTOR=role_manifest2=test

In this case the webserver::test to be called

NOTE: The parameter values from hiera the yaml files still uses the webserver.yaml file however class parameters need to be webserver::test::parm.

Role Ordering

the base role will always be run first but by default the other roles are run by puppet IN ANY ORDER!!! If you want the other roles run add to the puppet command the option --ordering=manifest

Resolving Class Parameters

Parameters for role can be set in the hiera hierarchy. They can be resolved from the hier /role/<role_name>.yaml and the role/<role_name>.yaml This allows values to be set for the particular environment. Also common parameters can be set in the common.yaml file which can also be specifed by environment.

Sample Puppet Repository

There is a sample puppet repository at https://github.com/neillturner/puppet_repo that implements this role functionality and includes the following additional files:

hiera.yaml

---
:backends:
  - yaml
:yaml:
  :datadir: /mypuppet_repo_dir/hieradata
:hierarchy:
  - "nodes/%{::hostname}"
  - "%{::environment}/roles/%{role_name1}"
  - "%{::environment}/roles/%{role_name2}"
  - "%{::environment}/roles/%{role_name3}"
  - "%{::environment}/roles/%{role_name4}" 
  - "%{::environment}/common"  
  - "roles/%{role_name1}"
  - "roles/%{role_name2}"
  - "roles/%{role_name3}"
  - "roles/%{role_name4}"   
  - common 

NOTE: In Puppet V4 hiera.yaml is stored with the environment so there will be separate hiera.yaml files for each environment. However the same hierarchy will apply and can be either shared with environments or kept separate for each environment if datadir is set to 'heiradata'.

site.pp (or whatever the initial manifest file is called)

#
#  Call Modules and Classes based on up to 4 roles 
#
#
node default {
  Exec {
    path => ["/bin", "/sbin", "/usr/bin", "/usr/sbin"],
  }
  # check if roles defined in node hostname hiera file.
  $hiera_role1 = hiera('role::role_name1','')
  if $hiera_role1 != '' {
    notify {"*** Found heira role::role_name1 value ${hiera_role1} ignoring all facter role values ***": }
    $role_name1 = hiera('role::role_name1','')
    $role_name2 = hiera('role::role_name2','')
    $role_name3 = hiera('role::role_name3','')
    $role_name4 = hiera('role::role_name4','')
    $role_manifest1 = hiera('role::role_manifest1','')
    $role_manifest2 = hiera('role::role_manifest2','')
    $role_manifest3 = hiera('role::role_manifest3','')
    $role_manifest4 = hiera('role::role_manifest4','')
  }
  class { 'role': }
  # Or to do Direct Module Prefix
  #class { 'role' : prefix => 'mycompany' }
  # Or to maintain compatibility with previous version that used a dash
  #class { 'role' : prefix => 'mycompany', separator => '-'  }
}

Testing

This can be tested by running in masterless puppet

export FACTER_role_name1=base
export FACTER_role_name2=webserver
puppet apply --modulepath ./modules manifests/site.pp

also an environment can be specified on the puppet apply command so that parameters values for different environments can be resolved from the hiera data.

This will also be able to run in puppet master: if the hostname is ubuntu-server set the roles in the hiera file hieradata/nodes/ubuntu-server.yaml on the puppetmaster

---
role::role_name1:  'base'  
role::role_name2:  'webserver' 

then run puppet agent -t --servername=puppetmaster.mycompany.com -v -d