Table of Contents

1. Challenge

   Set the Web Server Fact

   1. Move into the nginx module directory:

      cd /etc/puppetlabs/code/environments/production/modules/nginx/
      

   2. Create the plugin library location for Facter:

      sudo mkdir -p lib/facter
      

   3. Create and open a file called web.rb in the plugin location:

      sudo vim lib/facter/web.rb
      

   4. At its most basic, if we wanted to write a single, non-structured fact that output our web server information, we could write something like:

      Facter.add(:web) do
        setcode do
          'Nginx'
        end
      end
      

      Notice how this includes the Facter.add line to set our fact name, and the setcode statement, which provides us our output. Since we just want to supply the text Nginx, that is all we put in our statement block.

   5. However, since we need this to become a structured, aggregate fact, we're going to refactor this so we can add more facts to our code. Let's first define the overall web fact as an aggregate, which means the resolution of our web fact can be read in separate chunks:

      Facter.add(:web, :type => :aggregate) do
      

   6. Next, we want to replace our setcode statement with chunk, which lets us define the different parts of our structured fact:

      Facter.add(:web, :type => :aggregate) do
        chunk(:server) do
      

   7. We now need to update the structure of our output, so it resembles the JSON output we expected when we query for facts. To this, let's create a variable, web, then add our Nginx value as a structured key-value pair:

      Facter.add(:web, :type => :aggregate) do
        chunk(:server) do
          web = {:server => 'Nginx'}
          web
        end
      end
      

      Save and exit.

   8. Let's now test our fact:

      sudo puppet agent -t
      sudo facter -p web
      sudo facter -p web.server
      

2. Challenge

   Set the Version Fact

   1. Back in the lib/facter/web.rb file, create a second chunk line, this one called version; include a line at the end calling the web variable:

        chunk(:version) do
          web
        end
      

   2. We're going to check our version by using a slightly edited version of the nginx -v command — which means we need nginx for this fact to work. Let's add an if statement checking for nginx:

        chunk(:version) do
          if Facter::Core::Execution.which('nginx') != nil
          end
          web
        end
      

   3. Finally, we want to execute the appropriate command and have the output sent to a structured line mapped to web. Because our command is on the long side, you may want to create a variable for its output:

        chunk(:version) do
          if Facter::Core::Execution.which('nginx') != nil
            version = Facter::Core::Execution.execute('nginx -v 2>&1 | grep -Po [0-9]+\.[0-9]+\.[0-9]+')
            web = {:version => version}
          end
          web
        end
      

   4. If desired, save and test your code thus far.

3. Challenge

   Set the Fact for the Amount of Running Web Processes

   Mimic the same structures as the previous chunks to create the stanza that provides the amount of running processes:

     chunk(:processes) do
      processes = Facter::Core::Execution.execute('pgrep nginx | wc -l')
      web = {:processes => processes }
      web
     end
   

   The full file should look like:

   Facter.add(:web, :type => :aggregate) do
     chunk(:server) do
      web = {:server => 'Nginx'}
      web
     end
   
     chunk(:version) do
      if Facter::Core::Execution.which('nginx') != nil
        version = Facter::Core::Execution.execute('nginx -v 2>&1 | grep -Po [0-9]+\.[0-9]+\.[0-9]+')
        web = {:version => version}
      end
      web
     end
   
     chunk(:processes) do
      processes = Facter::Core::Execution.execute('pgrep nginx | wc -l')
      web = {:processes => processes }
      web
     end
   end
   

4. Challenge

   Test the New Facts

   Test that each fact works, as well as the overall web fact. Note that the second server is provided so you can test on a node with Nginx, as well as one without it (remember, our Puppet master does not have Nginx installed):

   sudo puppet agent -t
   sudo facter -p web
   sudo facter -p web.server
   sudo facter -p web.version
   sudo facter -p web.processes