This is a design pattern to implement roles like Chef and to separate class parameters into a parameter hierarchy also like chef.
Chef has two very useful features:
1.
Roles
A server node can have a role like say webserver. Then the cookbooks and recipes (modules and classes in Puppet terminology) that make up a webserver are related
to the role rather that the server node.
2.
Attribute Precedence.
Attributes (class Parameters in Puppet terminology) are kept separate from the cookbook (class) code and are applied in a hierarchy
of cookbook,recipe,node,role etc.
As well as being able to write more generic and reusable classes and see the class parameters for a particular server more easily
it is also also a much better way to use of existing pre-written modules from the puppet forge.
I have build a design pattern called
puppet_roles_hiera_parameters to implement these in puppet.
Puppet 3.3 incorporate hiera, a hierarchical keyword value store which is very useful to implement a separation of class parameter values
from the class module code.
Setup up to 4 role_nameX in Facter for the server.
-set the role_name1 to role_name4 in Facter
-the role class gets called from the site.pp.
-the role::role_nameX classes are called and the classes executed
-the class parameters are resolved in the hiera hierarchy:
nodes/%{hostname}
roles/%{role_name1}
roles/%{role_name2}
roles/%{role_name3}
roles/%{role_name4}
modules/%{module_name}
common
-role parameters can be stored in the roles/%{role_nameX} and can be overridden for parameter
values for the node,role or module.
parameters that are common to all roles can be stored in the common file.
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
This will also be able to run in puppet master, we just need to decide how to set the FACTER_role_name1 to 4.
References
Github - puppet_roles_hiera_parameters
roles and profiles
Role-based Puppet with Hiera
Github - vagrant-roles-demo
Github - puppet-roles
About Roles
Puppet for chef users
