Puppet+Hiera+Jenkins. Jenkins Integration

Continuation. By now we should have a working bundle of Puppet and Hiera, and in this post we will focus on Jenkins integration, as well as management of the apps configuration.

First, let's recall that roles contain class {'configuration':} declaration. This tiny module allows us to keep a current copy of the apps configuration on the target nodes.
Module's file tree looks as follow:

	.
	├── files
	│   ├── ci
	│   │   ├── enterprise_app_1
	│   │   │   ├── dir.1
	│   │   │   │   └── file.1
	│   │   │   ├── file.1
	│   │   │   └── file.2
	│   │   └── web_app_1
	│   │   ├── dir.1
	│   │   │   └── file.1
	│   │   ├── file.1
	│   │   └── file.2
	│   └── qa
	│   ├── enterprise_app_1
	│   │   ├── dir.1
	│   │   │   └── file.1
	│   │   ├── file.1
	│   │   └── file.2
	│   └── web_app_1
	│   ├── dir.1
	│   │   └── file.1
	│   ├── file.1
	│   └── file.2
	└── manifests
	└── init.pp

view raw configuration_tree.txt hosted with ❤ by GitHub

The manifest file itself (init.pp) is as follows:

	# file /biz/puppet/modules/configuration/manifests/init.pp
	class configuration ($application, $env){
	# creating directory structure first
	file { ['/biz', '/biz/configuration']:
	ensure => directory,
	mode => 0640,
	}
	file { "/biz/configuration/${application}":
	ensure => directory, # so make this a directory
	recurse => true, # enable recursive directory management
	purge => true, # purge all unmanaged junk
	force => true, # also purge subdirs and links etc.
	mode => 0640,
	source => "puppet:///modules/configuration/${env}/${application}",
	}
	}

view raw configuration hosted with ❤ by GitHub

It can be summarized as procedure that base on ${environment} name and ${application} name copies configuration files from /biz/puppet/hieradata/${environment}/${application} on Puppet Master to /biz/configuration/${application} on Puppet Agent node.

It is important that destination point has no reference of the ${environment}. This later allows Jenkins to perform configuration update in a complete agnostic way - with only ${application} name being required.

Consider the file tree under files folder. It is grouped by environment and application name. Should you like to add a new application, let's say HelloWorld to the CI env, you would have to:

1. Make sure that folder /biz/puppet/hieradata/ci exist
2. Create new subfolder /biz/puppet/hieradata/ci/HelloWorld
3. Place HelloWorld configuration files into /biz/puppet/hieradata/ci/HelloWorld 
4. Create/update Jenkins script to take the application configuration files from /biz/configuration/${application}
5. Create/update a role to reference the HelloWorld:

	class role::hello_world_server inherits role {
	# ...
	class { 'configuration' :
	env => "${environment}",
	application => 'HelloWorld',
	}
	}

view raw hello_world_role.pp hosted with ❤ by GitHub

The flow can be illustrated as:

Fig 1: Deployment process

Last, but not least - let's describe development process on Puppet+Hiera+Jenkins govern cluster:

Fig 2: Development process

Fig 2 illustrates that the framework significantly fast-tracks configuration changes. In summary, we have shown a configuration management framework targeted for small-to-medium sized project, where you are comfortable with file-based configuration for your applications.

Cheers!