Managing a DNS nameserver with PE

Write a small module to ensure that your nodes resolve to your internal nameserver.

1. From the command line on the Puppet master, navigate to the modules directory: cd /etc/puppetlabs/code/environments/production/modules
2. Run mkdir -p resolver/manifests
3. From the manifests directory, use your text editor to create the init.pp file, and edit it so it contains the following Puppet code.

   class resolver (
     $nameservers,
   ) {
   
     file { '/etc/resolv.conf':
       ensure  => file,
       owner   => 'root',
       group   => 'root',
       mode    => '0644',
       content => template('resolver/resolv.conf.erb'),
     }
   }

4. Save and exit the file.
5. Run mkdir -p resolver/templates to create the templates directory.
6. Use your text editor to create the resolver/templates/resolv.conf.erb file.
7. Edit the resolv.conf.erb so that it contains the following Ruby code. 

   # Resolv.conf generated by Puppet
   
   <% [@nameservers].flatten.each do |ns| -%>
   nameserver <%= ns %>
   <% end -%>
   
   # Other values can be added or hard-coded into the template as needed.

8. Save and exit the file.

To manage DNS on your nodes, create a new node group that contains all of your nodes.

1. In the console, click Classification, and click Add group. 
2. Specify options for the new node group:

   • Parent name – Select default

   • Group name - Enter a name that describes the role of this environment node group, for example, DNS.

   • Environment - Select Production

   • Environment group - Don't select this option

3. Click Add.
4. Click the DNS group,and select the Rules tab.
5. In the Fact field, enter name.
6. From the Operator drop-down list, select ~ (matches regex).
7. In the Value field, enter .* .
8. Click Add rule.

After you create a group, add a class to it.

1. In the console, select Classification, and then find and select the DNS group.
2. On the Configuration tab, in the Class name field, select resolver.
3. Click Add class, and commit changes.
   Note: The resolver class now appears in the list of classes for the DNS group, but it has not yet been configured on your nodes. For that to happen, you need to kick off a Puppet run.
4. From the command line of your Puppet master, run puppet agent -t.
5. From the command line of each PE-managed node, run puppet agent -t.

You can add class parameter values to the code in your module, but it’s easier to add those parameter values to your classes using the PE console.

1. In the console, select Classification, and then find and select the DNS group.
2. On the Configuration tab, find resolver in the list of classes.
3. From the parameter drop-down list, select nameservers.
4. In the Value field, enter the nameserver IP address you’d like to use (for example, 8.8.8.8).
   Note: The grey text that appears as values for some parameters is the default value, which can be either a literal value or a Puppet variable. You can restore this value by selecting Discard changes after you have added the parameter.
5. Click Add parameter, and commit changes.
6. From the command line of your Puppet master, run puppet agent -t.
7. From the command line of each PE-managed node, run puppet agent -t.

   This triggers a Puppet run to have Puppet Enterprise create the new configuration.

8. Navigate to /etc/resolv.conf. This file now contains the contents of the resolv.conf.erb template and the nameserver IP address you added in step 5.

If your infrastructure changes from what you've specified, PE corrects that change. To test this, make a manual infrastructure change and then run Puppet.

1. On any agent to which you applied the resolv.conf, edit /etc/resolv.conf to be any nameserver IP address other than the one you want to use.
2. Save and exit the file.
3. After Puppet runs, navigate to
4. Puppet runs.
5. Navigate to /etc/resolv.conf, and notice that PE has enforced the desired state you specified for the nameserver IP address.