To work through this recipe, you will need the following:

We'll start from the apache cookbook we've left in its 0.3.0 version. Bump it right now to 0.4.0 so we're starting fresh in apache/metadata.rb:

version '0.4.0'

Every resource can notify another resource to do something when its state changes, and any resource can also subscribe to a change of state from another resource. In our case, we'd like our template resource to notify the httpd system service to restart when the Virtual Host template changes, so we're sure the change is automatically taken into account. The httpd service is coming from the default Apache recipe, so it’s better to include it right now in the apache/recipes/virtualhost.rb file, so we’re sure this particular recipe works alone and not by side-effect of a previous inclusion:

include_recipe 'apache::default'

The cool thing is we can even see a diff of the change in the logs so we always know what's changed, as well as see the httpd service being reloaded after the change happened.

Our system is now perfectly dynamic and can reload its configuration at will at every change.

Puppet has exactly the same feature, using the notify attribute. When the content of /etc/apache2/sites-enabled is modified, Apache configuration needs to be reloaded.

Let's change our Apache manifest to do this.

Apache configuration needs to be reloaded when the default vhost is removed, so we need to modify modules/apache/manifests/init.pp with the corresponding notify attribute:

class apache {
    package {'apache2':
       ensure => present,
    }

    service {'apache2':
       ensure => running,
       enable => true
    }

    file {'/etc/apache2/sites-enabled/000-default.conf':
       ensure => absent,
       notify => Service['apache2'],
    }
}

The same logic applies for the virtual host creation (modules/apache/manifests/vhost.pp):

define apache::vhost (
     $website,
     $docroot
) {

  file { "/etc/apache2/sites-available/$website.conf":
     ensure  => present,
     owner   => 'root',
     group   => 'root',
     mode    => '0640',
     content => epp('apache/vhost.epp', 
                      {'website' => $website, 
                       'docroot'=>$docroot}),
  }

  file { "/etc/apache2/sites-enabled/$website.conf":
     ensure  => link,
     target  => "/etc/apache2/sites-available/$website.conf",
     require => File["/etc/apache2/sites-available/$website.conf"],
     notify  => Service['apache2'],
  }
}

Let's try to run the Puppet agent on fresh Vagrant boxes, we will see that the two modifications will schedule a configuration reload, that will be done at the end of the Puppet Agent run. (refer to the lines with Scheduling refresh of Service[apache2] and Triggered 'refresh' from 2 events):

Notice: /Stage[main]/Apache/File[/etc/apache2/sites-enabled/000-default.conf]/ensure: removed
Info: /Stage[main]/Apache/File[/etc/apache2/sites-enabled/000-default.conf]: Scheduling refresh of Service[apache2]
...
...
Notice: /Stage[main]/Main/Node[web.pomes.pro]/Apache::Vhost[web.pomes.pro]/File[/etc/apache2/sites-enabled/web.pomes.pro.conf]/ensure: created
Info: /Stage[main]/Main/Node[web.pomes.pro]/Apache::Vhost[web.pomes.pro]/File[/etc/apache2/sites-enabled/web.pomes.pro.conf]: Scheduling refresh of Service[apache2]
Notice: /Stage[main]/Apache/Service[apache2]: Triggered 'refresh' from 2 events
Notice: Applied catalog in 45.46 seconds

Now we can access the phpinfo page at http://web.pomes.pro without manually restarting Apache.