Generate puppetboard's random but not changing secret key by default

    Starting with Puppetboard 5.0.0 providing own $secret_key is required. See voxpupuli/puppetboard#721 for more info. If you run Puppetboard on a single node with static FQDN then you can set it the following code to generate a random but not changing value: ${fqdn_rand_string(32)}

manifests/profile/puppetboard.pp

@@ -56,6 +56,7 @@
     puppetdb_port     => $puppetdb_port,
     puppetdb_host     => $puppetdb_host,
     manage_virtualenv => $manage_virtualenv,
+    secret_key        => fqdn_rand_string(32),
   }
 
   if($ssl){